Comparison of GFRG with Conventional Systems

Comparison of GFRG Rapid Wall With conventional wall systems A DISSERTATION REPORT

Submitted by

SHIVACHANDRAN S Reg. No: 714714566015 in partial fulfillment for the award of the degree of

MASTER OF ARCHITECTURE (GENERAL) IN

RVS SCHOOL OF ARCHITECTURE

ANNA UNIVERSITY: CHENNAI 600 025 OCTOBER 2015

Chapter 1

Introduction

ABSTRACT HEADING The housing sector is the second largest energy consumer in India with 95 percent of urban population lying in the middle and lower income categories. Considering this demand for affordable housing, there is a strong potential for energy saving in the affordable housing sector. The given study delineates the gap in past research in creating comprehensive sustainable rating systems for energy efficient interventions in buildings and analyses the trade-offs in energy gains, economic cost and thermal comfort due to walling material substitution in warm-humid climate for an affordable housing unit. The study takes a government delivered affordable housing unit as case example. The DEROB-LTH software is used to simulate the hourly internal temperature throughout a day with six alternative walling systems. Hereafter, the three parameters – the embodied energy, cost of construction and the thermal comfort in terms of number of discomfort hours are compared to get a comprehensive sustainability assessment for the choice of walling materials. Flyash brick walls proved to be most efficient with respect to all three factors. Rapidwall, also called gypcrete panel is an energy efficient green building material with huge potential for use as load bearing and non load bearing wall panels. Rapidwall is a large load bearing panel with modular cavities suitable for both external and internal walls. It can also be used as intermediary floor slab/roof slab in combination with RCC as a composite material. Since the advent of innovative Rapidwall panel in 1990 in Australia, it has been used for buildings ranging from single storey to medium - high rise buildings. Light weighted Rapidwall has high compressive strength, shearing strength, flexural strength and ductility. It has very high level of resistance to fire, heat, water, termites, rot and corrosion. Concrete infill with vertical reinforcement rods enhances its vertical and lateral load capabilities. Rapidwall buildings are resistant to earthquakes , cyclones and fire.

INTRODUCTION

Being an emerging economy with rapidly rising per capita energy consumption and an increased dependency on energy imports, India is exposed to international energy market volatility and energy insecurity. As the urban housing sector of rapidly urbanizing India is facing a massive shortage of affordable housing, in order to address inclusive growth in the country, various affordable housing schemes are being planned by the Government of India in its five year plans. However all such policies and schemes, coming with hefty investments, fall silent upon energy consumption and conservation. The report of the high level task force on affordable housing chaired by Deepak Parekh in 2008 defined the concept of affordable housing in terms of size of tenement, multiples of household income and in terms of percentage of household income for rented accommodation. In this report, an affordable house in Economically Weaker Section (EWS) or Low Income Group (LIG) category is defined as a unit with a carpet area between 300 and 600 sq feet, with the cost not exceeding four times the household gross annual income and EMI/rent not exceeding 40 percent of the household’s gross monthly income. Evidently, such a nationally accepted benchmark also defined the capital cost components associated with affordable housing, but overlooked the factors related to sustainability and the associated recurring cost savings. The building sector in India consumed 29 percent of the total primary energy demand in 2009. This energy consumption in affordable housing is small compared to high income residences, commercial and institutional buildings. However, the demand for affordable housing constitutes about 95 percent of the housing market in India and hence forms a significant share of energy consumption in the household energy sector in the future. The threat of climate change caused by the increasing concentration of greenhouse gases in the atmosphere is pushing the whole world into a catastrophic crisis situation with universal concern. The need of the 21 st century is for energy efficient and eco-friendly products. The building industry accounts for 40% of CO 2 emissions. Building construction causes CO2 emissions as a result of embodied energy consumed in the production of energy intensive building materials and also the recurring energy consumption for cooling and heating of indoor environment. Significant studies have been carried in Indian context by The Energy and Resources Institute of India (TERI) which promotes and defines the concept of green buildings through its own building rating system named GRIHA (Green Rating for Integrated Habitat Assessment) [6], adopted as the national rating system for green buildings by the Government of India since 2007.

However the GRIHA guidelines give a sustainability scoring framework only and exclude the economic cost and comfort parameters that may be associated with energy efficient interventions for formulating a more holistic sustainable rating system achievable by the affordable housing sector. The Bureau of Energy Efficiency (BEE), which is a statutory body set up under the provision of Energy Conservation Act 2001, launched the Energy Conservation Building Code (ECBC) in 2007 [7] which sets minimum standards for energy efficient design, construction and retrofitting. GRIHA has 34 criteria based upon which rating of a green building project is performed, of which the ECBC makes up three criteria (criteria 6, 13 and 14). But the primary target of the ECBC is limiting energy consumption of HVAC systems that consume about 30-45 percent of operational energy in mechanically ventilated buildings. Considering this gap in the study of energy efficient interventions for affordable housing with naturally ventilated interior environment in hot countries, the given research explores a model for meeting a threefold target of improving life cycle energy consumption, minimizing cost and decreasing the perceived discomfort inside such housing units.

ENERGY CONSUMPTION FROM LIFE CYCLE ENERGY POINT OF VIEW Life cycle assessment (LCA) is a technique which is defined by the International Standardization Organization as to measure the environmental aspects and impacts of product systems, from raw material acquisition to final disposal, in accordance with the stated goal and scope as in ISO 14040 [8]. For building industry, LCA measures the overall impact of a building and its components on the environment in three different phases – the construction or the pre-use phase, the operation or the postoccupancy phase and the demolition phase of the building in a cradle-to-grave analysis. Out of these three phases, the energy consumption in the third, i.e. the demolition phase is negligible compared to the first two phases. However relative energy consumption in the first two phases depends upon the functional type of building, choice of materials and the choice of ventilation for the interior environment. Past studies on comparing LCA for various types of residential buildings have shown that in case of a single family residential unit, the right choice of materials in the pre-use phase with a slight possible increase in embodied energy may lead to very high amount energy saving in the use-phase [9][10]. It has also been seen that there exists a linear relationship between the operational energy use and the total energy use in a building life span, but a similar relation is not applicable with the embodied energy of the building. Hence a solar house or a passive house proved to be more energy efficient from life cycle energy point of view compared to a house built with the commitment to use “green” materials [11]. Therefore, while choosing materials in the pre-use or the construction phase, the numerical value for embodied energy should not be the sole criterion for introducing green interventions in whole lifecycle perspective of the building. Moreover, in Indian context, the concept of affordable housing is given by naturally ventilated buildings, since the cost of air conditioning adds considerably to the operation and maintenance cost, making it beyond affordability limits for the middle and lower income groups. As a result, the pre-use phase is an important target phase for energy efficient interventions for our aimed group of buildings, having an immense potential to provide an optimal thermal comfort during the building’s usephase. The given study explores walling material interventions which form an important factor for heat gain inside naturally ventilated building in predominantly hot climates. The given methodology can be extended to study the performance of other building elements in a sustainability framework.

PROPOSED METHODOLOGY Goal and scope of research The objective of this study is to derive a model that will help to choose a particular walling intervention from a number of available options by assessing the performance in three different aspects – economic cost, thermal comfort and net energy saving in terms of embodied energy. Though the given study does not perform a whole building LCA, the methodology aims at assessing the performance of a building material in whole life cycle of the building, owing to involvement of comfort parameters which bears relation with energy usage in operating phase for combating thermal discomfort. Functional unit - According to ISO 14040, the functional unit is the unit of comparison in the Life Cycle Inventory. In this study one square meter (m 2) of walling system is chosen as a unit and all energy consumptions and costs are expressed in terms of this functional unit e.g., MJ/m2 and Rupees/m2. System boundaries - The system studies the embodied energy of the walling materials during the pre-use phase. The recurrent embodied energy for maintenance and replacement during the use-phase, which recurs yearly about 1 to 3 percent of the initial embodied energy depending upon the building lifespan [12], is excluded. Though wind speed is an important determinant for thermal comfort in warm humid climate, it is a comfort parameter regulated by the size and location of window openings. Hence the effect of convective wind speed on internal temperature has been excluded in this study. Thermal perceptions and adaptive comfort equation Comfort standards on thermal comfort are essentially based upon either heat balance or adaptive models. While the previous model is suited for conditioned environments, the latter is more appropriate for naturally ventilated buildings [13]. Toe and Kubota developed an adaptive thermal comfort equation for naturally ventilated buildings in hothumid climates [14] using a statistical meta-analysis of the ASHRAE RP-884 database. Tneutop = 13.8 + 0.57 Toutdm

(1)

Where Tneutop denotes neutral operative temperature and T outdm denotes the daily mean outdoor temperature. This regression equation is applicable within a daily mean outdoor temperature range between 19.4 and 30.5 degree Celsius, with low (<0.3m/s) or moderate (<0.65m/s) wind speed at the neutral operative temperature, and with no required limit for relative humidity [16]. Equation (1) will be used to calculate the number of discomfort hours inside buildings in this study due to use of different walling materials. Alternative walling systems A walling system forms the vertical envelop of a building. The walling systems that have been compared in this study have been enlisted below:

Ordinary brickwork 215 mm thick external and 115mm thick internal walls with 1:6 mortar bonds and 1:4 sand cement plaster.

• • • • •

Solid plain cement concrete (PCC) in-situ wall with 200 mm thick plastered external wall and 100 mm thick internal wall with 1:4 sand cement plaster 215 mm thick external and 115 mm thick internal fly ash brick walls with 1:6 mortar bonds and 1:4 sand cement plaster Brick cavity wall with 115mm thick external and internal brickwork with 1:6 mortar bonds and 1:4 sand cement plaster and an air gap of 30mm in between Autoclaved aerated concrete (AAC) brick walls 200mm thick with 1:6 mortar bonds and 1:4 sand cement plaster, both for external and internal walls Glass fibre reinforced gypsum (GFRG) rapid walling system [15], consisting of glass fibre reinforced gypsum board panels 124mm thick with hollow cavities in filled by reinforced cement concrete for structural strength both for external and internal walls. The walling system does not require plastering.

Chapter 2

    

GFRG  WORKABILITY CONSTRUCTION METHODOLOGIES USES  PROPERTIES

Rapid wall Definition GFRG is the abbreviation for glass fibre reinforced gypsum. It is the name of a new building panel product, made essentially of gypsum plaster, reinforced with glass fibres, and is also known in the industry as Rapid wall. This product, suitable for rapid mass-scale building construction, was originally developed and used since 1990 in Australia. GFRG is of particular relevance to India, where there is a tremendous need for cost-effective mass-scale affordable housing, and where gypsum is abundantly available as an industrial by-product waste. The product is not only eco-friendly or green, but also resistant to water and fire. GFRG panels are presently manufactured to a thickness of 124 mm, a length of 12m and a height of 3m, under carefully controlled conditions. The panel can be cut to required size. Although its main application is in the construction of walls, it can also be used in floor and roof slabs in combination with reinforced concrete. The panel contains cavities that may be filled with concrete and reinforced with steel bars to impart additional strength and provide ductility. The panels may be unfilled, partially filled or fully filled with reinforced concrete as per the structural requirement. GFRG building panels are presently manufactured as Rapid wall, for the typical dimensions and material properties described in the manual. Typical dimensions of a GFRG building panel are 12.0m □□3.0m □□0.124 m, as shown in Fig.1.

Figure 1: Typical Cross Section of GFRG Panel

Source: GFRG/RAPIDWALL BUILDING STRUCTURAL DESIGN MANUAL

1

Each 1.0 m segment of the panel contains four ‘cells’. Each cell is 250 mm wide and 124 mm thick, containing a cavity 230mm□□□94 mm, as shown in Fig. 2. The various cells are inter- connected by solid ‘ribs’ (20 mm thick) and ‘flanges’ (15 mm thick), comprising gypsum plaster, reinforced with 300 - 350 mm glass fibre roving, located randomly but centrally. The skin thickness is 15 mm and rib thickness is 20 mm. Figure 2: Enlarged View of a Typical Cell Source: GFRG/RAPIDWA LL BUILDING STRUCTURAL DESIGN MANUAL

Rapid wall Uses In typical multistoried constructions involving the use of GFRG as load bearing structural walling, the connections between cross walls and with the foundations and floor/roof are achieved through reinforced concrete filling or R.C beams. All GFRG wall panels at the ground floor are to be erected over a network of RC plinth beams supported on suitable foundation. GFRG panel can also be used for intermediate floor slab/roof slab in combination with RC (Refer Figs Figure 3: Erection of GFRG panels over plinth 4.4). The strength of GFRG slabs beam at site can be significantly enhanced by embedding reinforced concrete micro beams. For providing embedded micro beams, top flange of the respective cavity is cut and removed in such a way that minimum 25 mm flange on both end is protruded as shown in Fig. 4.4. RC concrete screed of minimum 50 mm thickness is provided above the GFRG floor panel, which is reinforced with weld mesh of minimum size of 10 gauge 100 mm × 100 mm. This RC screed and micro beam act together as series of embedded Tbeams. The thickness of the RC screed, reinforcement and interval of embedded RC micro beams depends on the span and intensity of imposed load. The connectivity between the horizontal tie beam, embedded RC micro beams, concrete screed and vertical rods in GFRG wall, and ensures perfect connection between floor/roof slab and walling system.

Fig.1 : Worlds’ largest load bearing lightweight panel being used in Australia PHYSICAL AND MATERIAL PROPERTIES Rapidwall panel is world’s largest loadbearing lightweight panels. The panels are manufactured with size 12 m length, 3m height and 124 mm thickness. Each panel has 48 modular cavities of 230 mm x 94 mm x 3m dimension. The weight of one panel is 1440 kg 3 or 40 kg/sqm. The density is 1.14g/cm , being only 10-12% of the weight of comparable concrete /brick masonry. The physical and material properties of panels are as follows: Weight- light weight 40 Kg/ sqm Axial load capacity 160 kN/m{ 16 tons/ m} Compressive strength 73.2 Kg/cm2 Unit Shear strength 50.90 kN/m 2 21.25 kg/cm Flexural strength Tensile Strength 35 KN/ m Ductility 4 0 4 hr rating withstood 700-1000 C Fire resistance Thermal Resistance R 0.36 K/W “U “Value 2.85W/M2K Thermal conductivity 0.617 Elastic Modulus 3000-6000Mpa Sound transmission{STC} 40 Water absorption < 5% The vertical and lateral load capability of Rapidwall Panel can be increased many fold by infill of concrete after placing reinforcement rods vertically. As per structural requirement, cavities of wall panel can be filled in various combinations (See Fig.2.) JOINTS: Wall to wall ‘L’, ‘T’, ‘+’ angle joints and horizontal wall joints are made by cutting of inner or outer flanges or web appropriately and infill of concrete with vertical reinforcement with stirrups for anchorage. Various constructio n joints are illustrated in Fig.3.

2

Fig.2 : RCC infill to increase load capability

Fig.3 Various construction joints Rapidwall Panel can also be used for intermediary floor slab / roof slab in combination with embedded RCC micro-beams and RCC screed concrete (Fig.4).

3

Fig.4 GFRG embedded with RCC micro beams and RCC screed concrete

4

FOUNDATION: For Rapidwall buildings/ Housing a conventional foundation like spread footing, RCC column footing, raft or pile foundation is used as per the soil condition and load factors. All around the building RCC plinth beam is provided at basement plinth level. For erection of panel as wall, 12 mm dia vertical reinforcement of 0.75m long of which 0.45m protrudes up and remaining portion with 0.15m angle is placed into the RCC plinth beams before casting. Start up rods are at 1m centre to centre. Fig 5 : Foundation RAPIDWALL FOR RAPID CONSTRUCTION Rapidwall enables fast track method of construction. Conventional building construction involves various cumbersome and time consuming processes, like i) masonry wall construction ii) cement plastering requiring curing, iii) casting of RCC slabs requiring centering and scaffolding and curing iv) removal of centering and scaffolding and v) plastering of ceilings and so on. It also contributes to pollution and environmental degradation due to debris left on the site. In contrast, Rapidwall construction is much faster and easier. There will be no debris left at site. Construction time is minimized to 15-20%. Instead of brick by brick construction, Rapidwall enables wall by wall construction. Rapidwall also does not require cement plastering as both surfaces are smooth and even and ready for application of special primer and finishing coat of paint. Rapid Construction Method As per the building plan, each wall panel will be cut at the factory with millimeter precision using an automated cutting saw. Door/window/ventilator, openings for AC unit etc will also be cut and panels for every floor is marked relating to building drawing. Panels are vertically loaded at the factory on stillages for transport to the construction sites on trucks. Each stillage holds 5 or 8 pre-cut panels. The stillages are placed at the construction site close to the foundation for erection using vehicle mounted crane or other type of crane with required boom length for construction of low, medium and high rise buildings. Special lifting jaws suitable to lift the pane l are used by inserting into the cavities and pierced into webs, so that lifting/handling of panels will be safe. Panels are erected over the RCC plinth beam and concrete is infilled from top. Protruded start up rods go inside cavities as can be seen from Fig. 5. All the panels are erected as per the building plan by following the notation. Each panel is erected level and plumb and will be supported by lateral props to keep the panel in level, plumb and secure in position. Once wall panels erected, door and window frames are fixed in position using conventional clamps with concrete infill of cavities on either side. Embedded RCC lintels are to be provided wherever required by cutting open external flange. Reinforcement for lintels and RCC sunshades can be provided with required shuttering and support. 5

Concrete infill After inserting vertical reinforcement rods as per the structural design and clamps for wall corners are in place to keep the wall panels in perfect position, concrete of 12 mm size aggregate will be poured from top into the cavities using a small hose to go down at least 1.5 to 2 m into the cavities for directly pumping the concrete from ready mix concrete truck. For small building construction, concrete can be poured manually using a funnel. Filling the panels with concrete is to be done in three layers of 1m height with an interval of 1 hr between each layer. There is no need to use vibrator because gravitational pressure acts to self compact the concrete inside the water tight cavities. Embedded RCC tie beam all around at each level floor/roof slab: An embedded RCC tie beam to floor slab is to be provided at each floor slab level, as an essential requirement of national building code against earth quakes. For this, web portion to required beam depth at top is to be cut and removed for placing horizontal reinforcement with stirrups and concreted. Rapidwall for floor/ roof slab in combination with RCC Rapidwall for floor/roof slab will also be cut to required size and marked with notatio n. First the wall joints and other cavities and horizontal RCC tie beams are in- filled with concrete ; then wooden plank of 0.3 to 0.45 m wide is provided to room span between the walls with support wherever embedded micro beams are there; finally roof panels will be lifted by crane using strong sling tied at mid-diagonal point, so that panel will float perfectly horizontal (See Fig.5) Fig 5 Floor/roof panel Each roof panel is placed over the wall in such a way that there will be at least a gap of 40 mm. This is to enable vertical rods to be placed continuously from floor to floor and provide monolithic RCC frame within Rapidwall. Wherever embedded micro-beams are there, top flanges of roof panel are cut leaving at least 25mm projection. Fig 6 : Cutting of top flange

Fig 7 : Reinforcement 6

Reinforcement for micro-beams is placed and weld mesh as reinforcement is placed (Fig 7). Concrete is poured for miro-beams and RCC slab. This results in the embedded RCC micro beams and 50 mm thickness screed concrete becoming a series of “T” beams. Erection of wall panel and floor slab for upper floor The following day, erection of wall panels for the upper floor can be arranged. Vertical reinforcement of floor below is provided with extra length so as to protrude to 0.45 m to serve as start up rods and lap length for upper floor. (See Fig.8) Once the wall panels are erected on the upper floor, vertical reinforcement rods are provided, door/window frames fixed and RCC lintel cast. Then concrete is filled where required and joints are filled. Then RCC tie beam all around are concreted. Roof panel for upper floor is repeated same as ground floor. For every upper floor the same method is repeated. Fig 8 : Erection of upper floor panel Finishing work th

Once concreting of ground floor roof slab is completed, on the 4 day, wooden planks with support props in ground floor can be removed. Finishing of internal wall corners and ceiling corners etc can be done using wall putty or special plaster by experienced POP plasterers. Simultaneously, electrical work, water supply and sanitary work, floor tiling, mosaic or marble works, staircase work etc can also be carried out. Every upper floor can be finished in the same way. Monolithic RCC framed structure inside Glass Fiber Reinforced Gypsum Panel. In Rapidwall building an embedded monolithic, thin RCC framed structure is formed by i) bottom RCC plinth beams, ii) vertical columns of infilled cavities, iii) vertical wall corner joints iv) inter-connected horizontal RCC tie beams, integrated with v) embedded RCC micro-beams and RCC screed in all floors. In effect this RCC frame is moulded inside the GFRG Panel. (See Fig. 9)

Fig 9 :Monolithic RCC framed structure Testing of Rapidwall in Australia and by Tianjin University, in Zhandong Province, China found that“the lateral resistance of the concrete filled GFRG walls come from two different actions viz i) the shear resistance of the Rapidwall and ii) the lateral resistance 7

of internal reinforced concrete cores”as per the paper published by Yu-Fei Wu and Xiang in RILEM 2007(1) . The strength of building to take care of axial load and lateral/ flexural/ shear loads from wind or cyclone or earthquakes is due to the combination of insid e RCC frame and Rapidwall Panel. Since the reinforced steel also encased within the GFRG panel, it is protected from corrosion. Rapidwall building/ housing is cooler Conventional building materials like concrete have high thermal conductivity and low thermal resistance. Conventional concrete roof and walls radiate heat inside the building. Heavy electrical energy is to be used to maintain indoor comfort level. There will be high electric energy for heating the indoor during winter. In contrast Rapidwall panel have low thermal conductivity and high thermal resistance. A comparative research study by Mohd Peter Davis et al in 2000 in Universiti Putra Malaysia, Selangor, found that in summer indoor temperature of Glass Fiber Reinforced Gypsum Panel building is cooler by 5 to 6 degrees Celsius as compared to concrete building (2). The high thermal resistance of Rapidwall will keep interiors cooler in summer and warmer in winter, saving substantial recurring energy use. Rapidwall is energy efficient Low energy consumption for mass production of building material and reduced use of recurring energy for operational use is very critical to achieve carbon emission reduction to save the environment and fight global warming. This is the need of the century. The main raw material is calcined superior quality gypsum plaster with purity more than 90%. Gypsum plaster, also called Plaster of Paris, is produced by calcining natural mineral gypsum rock (CaSO 42H2O) or by calcining industrial waste by-product gypsum available abundantly in India at various locations across the country. The use of advanced low energy based green & cleaner technology in reprocessing / recycling the raw material into GFRG panels consumes very low energy and helps to protect the environment. Environmental protection is economically priced now through carbon emission reduction (CER) trading under Kyoto Protocol linked through special market mechanism (CDM - Clean Development Mechanism). This makes Rapidwall Panel mass production very suitable to meet the challenge of affordable housing for the deprived. According to the Ministry of Housing, Govt of India in Dec 2007 urban housing shortage has been estimated at about 24.7 million units at t h the end of the 10 Five Year Plan (2006-07) and 99% of the shortage pertains to the economically weaker sections and low income groups. Rapidwall is for affordable quality housing Access to adequate shelter at affordable cost by low income section and common people is very important for India for inclusive development.. The booming of real estate and construction industry has indeed shot up the cost of construction due to the ever increasing cost of cement, steel, bricks, river sand, concrete materials and labour cost. In this situation, safe and good quality housing will become unaffordable to all the sections.

Trends in cost (INR) of brick masonry/sqm with 2 sides cement plastering 2003-8 2000 1500

1700

1000 500

1140 460

510

2003

2004

1300

780

0 2005

2006

2007

2008 May

Fig.10 Cost of construction of 1 sqm (10.76 sft or 8.12 cft) 9” thick quality brick wall in cement mortar 1:6 and both sides (2 sqm or 21.52sft) plastered in cement mortar 1:5 Commonly used walling in India is brick masonry. Cost of brick wall with two sides cement plastering has increased by almost 4 times during the last 5 years as seen in Fig.10. Brick wall construction cost was Rs 460/sqm in 2003. This increased to Rs 1700 /sqm in 2007. In view of likely increase in cost of energy, bricks, cement, river sand, water, labour and hire charges for scaffolding etc, the cost of masonry made of bricks or concrete blocks will continue to rise in future. This will make Rapidwall panel much cheaper and affordable to the building industry while it will also help to protect the environment, as one sqm panel will save carbon emission reduction of about 80Kg. Rapidwall panel has excellent acoustic properties. Testing of panel by IIT Madras found that the panel belongs to a class of STC 40 with respect to air-borne sound insulation. Infill of cavities with locally available cheaper materials like quarry dust mixed with cement (1:20) and water or sand and cement (1:20) up to lintel/ window height can make the wall solid and address security-related concerns. Other than Australia and China, India is set to benefit from the technology as Rapidwall panels are to be manufactured and marketed in Mumbai within few months by RCF, one of the largest fertiliser company of Govt of India . FACT, another large public undertaking fertiliser company in joint venture with RCF is also setting up another Rapidwall plant in Cochin. A Rapidwall plant near Chennai is also commissioning and marketing the product shortly. In Rapidwall construction, especially in repetitive type mass housing, time for construction will be reduced by 75-80% thereby reducing overall overhead establishment costs with reduced lock up investment period and less labour component. Comparative study of Rapidwall building and conventional building (2 storey 1500 sft) shows significant savings in Rapidwall buildings. Embodied energy of Rapidwall building is only 82921 kWh, while conventional same size building would have 215400 kWh, thereby saving 61.5% embodied energy. (See Table 1)

Materials/ items

Rapidwall Building

Saving in %

16 tons 1800 kg 20 cum 38 cum 500sqm 50000 ltr 143 sqm 389 mandays 21 days 170 tons

Conventional Building 32.55 tons 2779 kg 83.37 cum 52.46 cum 57200 200000ltr 154.45sqm 1200 mandays 120 days 490 tons

Cement Steel River sand Granite metal Bricks GFRG Panel Water Built Area Labour Construction Time Total Weight of superstructure Construction Cost Embodied energy in kWh

Rs 13.25 lakhs 82921

Rs 18.27 lakhs 215400

27.47% 61.5

50.8 35.2 76 27.56

75 8 67.59 82 65

Table 1: Comparison of Rapidwall vs conventional building

Uses of Rapidwall The most valuble use of Rapidwall is its use as load bearing wall in multi- storey construction in combination with RCC. Rapidwall can also be used as non load bearing and partition wall in RCC framed structures. IIT Madras has recently developed method of fixing panel in between RCC columns, beams and floor slab with clamping system. By this panel can be fixed to floor slab and panel at bottom using screws, which will be embedded within flooring and skirting. At top clamps will be fixed to panel and ceiling slab or beam. On sides also clamped at bottom to RCC column, floor slab and panel. Plastering of walls can also be saved thereby saving time and cost. If this is taken into account at design stage itself, dead load reduction of more than 50% can be made.This will save in foundation, RCC columns and beams, in turn steel and concrete. This will make substantial savings in cost of construction . RCC Columns, beams with Rapidwall floor and walls in high rise building: One of the leading architects based in Mumbai proposed an innovative method of construction of high rise building with RCC columns and beams to take load, while panel is to be used for walls and floor slab with micro beams. For this specially designed shuttering for RCC columns and beams will be in position in such a way that wall panel and floor slab panel of ground floor will be in position. Concreting of columns, beams, infill of required cavities, micro beams, and screed will be done simultaneously. This process will be repeated on each upper floor. Walls of each floor construction will be done along with rising up structure. It is estimated that this method will reduce 50% dead load which will reduce substantial steel and cement, 8% increased carpet area and saving of 60-70 % time.

Scattered small and row houses: Quality small houses and row houses for low income and common people which can resist natural disasters at affordable cost is essential for inclusive development. Housing of the masses as well as other segments along with infrastructure alone will determine growth and development of the society or the nation. One BHK housing from 300-500 sft at affordable cost @ Rs 600-700/ sft can be a reality with Rapidwall. At a time when the real estate market is on the downslide due to the economy in recession, many builders who have embarked on mega residential schemes may find affordable housing as a catalyst to tide over the recession period. It need not mean that they need to build houses for low income or middle class alone, but with structures built at affordable cost using Rapidwall and carry out superior finish to meet the requirement of up market and luxury segment may be a good solution and response . While provide more comfortable living , this will also save energy , contribute to environmental protection and fight global warming. Construction of compound wall: Rapidwall can be used for construction of compound wall and security wall. Gypsum based wall plaster and wall putty will be alternative to cement plaster for interior walls and ceiling. This will save river sand , cement and water. It will also provide fine finish. Gypsum based wall putty will be superior product than currently marketed brands of wall putty. These products will also be very useful to the real estate and housing industry.

RTIFICATION System in Brief

Glass Fibre Reinforced Gypsum (GFRG) Panel known as Rapidwall is a building panel made-up of calcined gypsum plaster, reinforced with glass fibers. The panel was originally developed by GFRG Building System Australia and used since 1990 in Australia for mass scale building construction. Now, these panels are being produced in India and the technology is being used in India. The panel, manufactured to a thickness of 124mm under carefully controlled conditions to a length of 12m and height of 3m, contains cavities that may be unfilled, partially filled or fully filled with reinforced concrete as per structural requirement. Experimental studies and research in Australia, China and India have shown that GFRG panels, suitably filled with plain reinforced concrete possesses substantial strength to act not only as load bearing elements but also as shear wall, capable of resisting lateral loads due to earthquake and wind. GFRG panel can also be used advantageously as in-fills (non-load bearing) in combination with RCC framed columns and beams (conventional framed construction of multi-storey building) without any restriction on number of storeyes. Micro-beams and RCC screed (acting as T-beam) can be used as floor/ roof slab. The GFRG Panel is manufactured in semi-automatic plant using slurry of calcined gypsum plaster mixed with certain chemicals including water repellent emulsion and glass fibre rovings, cut, spread and imbedded uniformly into the slurry with the help of screen roller. The panels are dried at a temperature of 275oC before shifting to storage area or the cutting table. The wall panels can be cut as per dimensions & requirements of the building planned. It is an integrated composite building system using factory made prefab load bearing cage panels & monolithic cast-in situ RC in filled for walling & floor/roof slab, suitable for low rise to medium rise (single to 10 storeys) building.

Classification

Application

Class – 1 – Water resistant grade – GFRG panel for external walls, in wet areas and / or as floor and wall formwork for concrete filling. Class – 2 – General Grade – GFRG panels for structural application or non–structural application in dry areas. These panels are general unsuitable for use as wall or floor formwork and Class – 3 – Partition Grade – GFRG panel as non–structural internal partition walls in dry areas only. GFRG panels may generally be used in following ways: As load Bearing Walling – With cavities filled with reinforced concrete is i) suitable for multi – storeyed housing. In single or two storeyed construction, the cavities can remain unfilled or suitably filled with non – structural core filling such as insulation, sand, quarry dust, polyurethane or light weight concrete. As partition walls in multi storeyed frame buildings. Panels can also ii) be filled suitably. Such walls can also be used as cladding for industrial buildings or sport facilities etc. iii) As compound walls / security walls. As horizontal floor slabs / roof slabs with reinforced concrete micro iv) beams and screed (T-beam action). This system can also be used in inclined configuration, such as staircase waist slab and pitched roofing.

Dimension

Typical Dimension of GFRG building panel are 12.0m x 3.0m x 0.124m Each 1.0m segment of the panel contains four cells. Each cell is 250mm wide and 124mm thick (see Fig.1).

Fig 1 Enlarged view of a Typical Cell

Mechanical Properties (unfilled panels) - based on test results:

Mechanical Properties

Nominal Value

Unit weight Modulus of elasticity, E G

0.433 kN/m2 7500 N/mm2

Uni-axial compressive strength, Puc

160 kN/m (4.77 mPa)

Uni-axial tensile strength, Tuc

34 – 37 kN/m

Remarks

Strength obtained from longitudinal compression / tension tests with ribs extending in the longitudinal direction.

Ultimate shear strength, Vuc Out-of-plane moment capacity, Rib

21.6 kN/m 2.1 kNm/m

parallel to span, Muc Out-of-plane moment capacity, Rib 0.88 kNm/m perpendicular to span, Muc , perp Mohr hardness Out-of-plane flexural rigidity, EI, Rib

1.6 3.5 x 1011 Nmm2/m

parallel to span Out-of-plane flexural rigidity, EI, Rib 1.7x1011Nmm2/m perpendicular to span Coefficient of thermal expansion, Cm

12x10-6mm/mm/oC 1.0% : 1 hr

Water absorption

Average water absorption by weight % after certain hours of

3.85% : 24 hrs immersion. Fire resistance : Structural adequacy / integrity / insulation

140/140/140 minutes

CSIRO, Australia/ IS 3809:1979

Sound transmission class (STC) 40 dB ISO 10140-3:2010* * ISO 10140-3:2010 - Acoustics -- Laboratory measurement of sound insulation of building elements -- Part 3: Measurement of impact sound insulation Source: GFRG/Rapidwall Building Structural Design Manual

Structural Design The design capacities are based on limit state design procedures, considering, the ultimate limit state for strength design, treating the 3.0 m high GFRG building panel as the unit material and considering the strength capacity as obtained from the test results. The design should be such that the structures should withstand safety against all loads (as per relevant Indian Standards) likely to act on the structure during its lifetime. It shall also satisfy the serviceability requirements, such as limitations of deflection and cracking. In general the structure shall be designed on the basis of the most critical limit state and shall be checked for other limit states. Detailed design Guidelines are given in “Use of Glass Fibre Reinforced Gypsum (GFRG) Panels in Buildings - Structural Design Manual” prepared by IIT Madras and published by BMTPC. It may be obtained on request from BMTPC. Experimental studies and research have shown that GFRG Panels, suitably filled with reinforced concrete, possess substantial strength to act not only as load bearing elements, but also as shear wall, capable of resisting lateral loads due to earthquake and wind. It is possible to design such buildings upto 10 storeys in low seismic zone. (and to lesser height in high seismic zone). However, the structure needs to be properly designed by a qualified structural engineer. Manufacture of GRFG Panels with increased thickness (150 mm – 200 m) with suitable flange thickness can facilitate design and construction of taller buildings.

The basis arrangement of GFRG Panel Building System is as follow:

Transportation

Construction

The GFRG panels are transported from factory to generally through trucks site, or trailers. The panels are kept in a vertical position “stillages” so as to avoid using any damage during transportation. The panels after the site are taken out reaching from trucks using cranes. Forklifts can be used for easier movement of panels from one area to another. The foundation used in the construction is conventional and is designed generally as strip footing depending upon the soil condition. For superstructure – plinth beams are cast all around the floor, where walls have to be erected. The superstructure is entirely based on prefabricated panels. The procedure mainly include fixing of wall panels and roof panels using mechanical means, preferably a crane and filling the required joint with reinforced cement concrete as per structural design. Waterproofing is an essential requirement of the construction at different stages. Detailed guidelines for waterproofing is require to be followed while constructing the building.

Limitation of Use

• The shorter span of slab (floor / roof) should be restricted to 5 m. • Is ideal if the same floor / roof is replicated for all floors in multi storeyed structure. For any variations, structural designer needs to be consulted. • Curved walls or domes should be avoided. In case it is essential, use masonry / concrete for that particular area. • The electrical / plumbing drawing should be such that most of the pipes go through the cavities (in order to facilitate minimum cutting of panel)

f the System

Green Technology It makes use of industrial waste gypsum. Does not need any plastering. Uses much less cement, sand, steel and water than conventional building. It consumes much less embodied energy and less carbon footprint. Reduced built area Panels being only 124 mm thick, for the same carpet area, the built up area and the building footprint is much less than conventional buildings. This is particularly advantageous in multi storey mass housing. Versatility roofs and

Panels can be used not only as walls but also as floors, staircase.

Speed of Construction Using the system, the construction of a building can be very fast compared to the conventional building. One building of two storeyed (total 1981 sqft with four flats) was constructed in IIT Madras in one month. Lightness of structures These panels are very light weight only 43 kg/m 2. Even after filling some of the cavi-bringing safety against ties with concrete, the overall building weight is much less, contributing to significant earthquake forces reduction in design earthquake forces and savings in foundation and overall buildings cost especially in multi – storeyed buildings. Manufacturing Plants Presently two plants are working in India: 1) Rashtriya Chemicals and Fertilizers Limited, “Priyadarshini”, Eastern Express Highway, Sion, Mumbai. 2) FACT – RCF Building Products Ltd., FACT Cochin Division Campus, Ambalamedu, Kochi (Kerala). The panels manufactured at the above plants are based on the technology transferred through collaboration with GFRG Building System, Australia. BMTPC under Performance Appraisal Certification Scheme has evaluated the Panel manufactured at RCF Mumbai and FRBL Cochin and issued PAC No. 1008-S/2011 and PAC No. 1009-S/2012 respectively. (Available for download from BMTPC website www.bmtpc.org).

Constructed at IIT Madras Campus, in one month duration. Few Building Constructed in India are: i) Residential buildings at Udipti Karnataka owner Mr. Satish Rao, built by Harsha Pvt. Ltd., Udipi, Bangalore. ii) Utility Building for Konark Railways at Madgao, South Goa, built by Harsha Pvt. Ltd., Udipti, Banga-lore. iii) Residential building at Udipti by Harsha Pvt. Ltd. iv) 3 storey residential building at Calicut by NMS Rapidwall Construction Company, Calicut (2014). v) Two storeyed building at IIT Madras. vi) Residential building at RCF Mumbai. Model house at Cochin

Chapter 3

Investigation on the Performance of  Alternative Walling Materials in an  Affordable Housing Unit situated in Warm Humid Climate 

Case study building The case study is a low income group housing complex located in the Rajarhat area, an eastern metropolitan extension of Kolkata. The region comes under subtropical warm humid climate zone owing to its latitude and proximity to the sea.

(a) Figure 1 -

(b) (a) Front side view and (b) back side view of building blocks

Figure 2 - Typical floor plan of a ‘Starlit’ housing block highlighting the bedroom in the south-west oriented unit, simulated for hourly internal temperature

The case study buildings,  as shown in figure 1,  were built in an affordable housing scheme named ‘Starlit Housing’ and delivered by the State Housing Board in 2011. The buildings have been occupied since then by low income group of residents. Each block is a four storied building and the entrance of each is oriented in the east­west direction in the site plan. Each floor has one­bedroom units, four in number, oriented in the four different intercardinal directions. The study took a south­ west oriented unit as case example for carrying out simulations, as shown in figure 2. Simulations For simulating the internal room temperatures in the case study unit, the study used the DEROB­ LTH software originating from the University of Texas at Austin, USA and further developed by the Department of Energy and Building Design at the Lund University, Sweden. The software uses the Crank­Nicholson’s Difference method for heating diffusion equations in walls and the Gauss­Seidel method is simultaneously used to solve the temperature difference in nodes. Nodes are assigned to walls   and   windows   for   energy   transmission.   The   hourly   internal   temperature   simulation   has   been validated in several past studies.

Figure 3 ­ DEROB model showing the bedroom whose internal temperature has been simulated with alternative building materials Choice   of   orientation  ­   The   south­west   corner   was   chosen   for   simulation.   The   chosen orientation is due to the sun path from east to west via south in the northern hemisphere, and the west facing rooms having maximum discomfort during the daytime due to excess glare from sunlight. th

Choice of date  ­ The chosen day for hourly indoor temperature simulation is March 20  of a typical year from the Meteonorm climate database fed in the DEROB­LTH software. This is the spring equinox day in the northern hemisphere with equal days and equal nights which indicates the onset of summer. Parametric modelling – The DEROB program can handle upto eight volumes and upto hundred walls. Due to these modelling limitations, only one of the units has been modelled and the internal temperature in the south­west facing bedroom has been simulated as shown in the Figure 3. The parametric simulations have been run in a closed window scenario assuming 30 percent absorptivity for the walls and the roof, which is the highest absorptivity for white painted surface [18]. Simulations have been carried out for a ground floor unit using the standard RCC roof, single glazed windows and plywood doors. Material database – The material databases for simulation have been derived from for flyash, for autoclaved aerated concrete, for GFRG rapid wall and the rest from the DEROB­LTH database.

RESULTS The embodied energies of the alternative building materials were calculated from. The cost of construction are as per West Bengal Public Works Department schedule rates for 2010 till its fourth amendment. The rates for GFRG panels and AAC blocks have been derived. The costs compared below include the cost of plastering but exclude the cost of painting.

Figure 4­

Simulated room temperature in various wall types with alternative building materials

The figure 4 shows the internal simulated temperatures (T s) for all the walling systems used in this   study,   done   in   the   DEROB­LTH   software.   The   number   of   discomfort   hours   is   obtained   by comparing the value of Ts for each hour with the neutral operative temperature (T neutop) on the given date (March 20) of a typical year, which was 29.38 degC against a daily mean outdoor temperature (Toutdm) of 27.3 degC. The degrees of discomfort were calculated by taking the cumulative of the excess temperatures above the Tneutop during the discomfort hours.The graphs clearly delineate the time lag in heat content of the building materials, having higher internal temperatures in the later parts of the day. The  Table 1  gives a comparative analysis of the walling elements in cost, comfort and energy saving scale. Brick cavity wall seems to give marginally better thermal comfort than ordinary brick wall. Thermal discomfort seems to be highest in aerated concrete walls. Flyash bricks are found to be most efficient in terms of all three factors. Table1. Material properties in terms of cost, comfort and energy saving

Walling system Ordinary Brick wall Brick cavity wall Solid PCC in­situ wall Fly ash brick wall AAC wall GFRG rapid wall

Embodied Energy (MJ/sq m construction)

Construction Cost (Rs/ sq m construction)

1231.0 1118.5 441.36 376.5 369.0 474.0

1451.46 1462.39 1675.60 1272.34 1028.00 1620.00

No. of Degrees of Discomfort Hrs Discomfort 0 (Tneutop=29.38 C) 8 7 7 5 10 9

4.06 2.84 2.04 0.9 10.2 14.7

DISCUSSIONS

The given study is carried out in warm humid climate characterized by uncomfortable summers where it is important to simulate the peak summer temperatures for thermal comfort. However the

st

average outdoor temperature for 21   June, which marks the summer solstice or the peak of summer, did not fall in the temperature range for which the adaptive thermal comfort equation, used in this study, is applicable. Hence this date could th

not be taken for the study. Instead the spring equinox day occurring on 20   March was assumed for demonstrating the thermal comfort performance of the building walling materials in terms of number of discomfort hours. This particular shortcoming   was   addressed   by  introducing   two   indicators   of   thermal  discomfort  –   “number   of   discomfort   hours”   and cumulative of the degrees above the neutral operative temperature on the particular day given by “degrees of discomfort”. st

Flyash bricks were seen to excel in both the thermal performance indicators. The simulated temperatures for June 21  gave discomfort hours round the clock for almost all the materials, the T neutop in such case being assumed from the upper limit of the   Toutdm  for   the   equation   (1),   which   is   30.5   degC.   Hence   these   results   were   not  shown   in   the   study.   However   the comparative ranking of various walling materials on th

rhermal comfort on this day based upon the “degrees of discomfort” indicator followed a trend similar to 20  March. The comparative performance assessment for thermal comfort for various walling materials in the given study is also dependent upon the specific heat, density and thermal conductivity of the walling materials. These three physical properties are often seen to vary with the manufacture of the material and the proportion of its composites. The thermal properties of AAC blocks for example are largely dependent upon the proportion of flyash in a block. Hence these results are subject to variations depending upon changing material compositions and properties. Thus the target of the given study is to delineate a methodology for sustainability assessment of various walling materials based upon the available data inputs.

Chapter 4

Manufacturer’s Standards By FACT INDIA, Cochin 

DESCRIPTION OF SYSTEM

Name of the System– Glass Fibre Reinforced Gypsum Building Panel System Market Name: Rapidwall Panel Glass Fiber Reinforced Gypsum (GFRG) Panel branded as Rapidwall is a building panel product, made of calcined gypsum, plaster, reinforced with glass fibers, for Mass-scale building construction, was originally developed and used since 1990 in Australia. The panel, manufactured to a thickness of 124mm under carefully controlled conditions to a length of 12 m and height of 3m, contains cavities that may be unfilled, partially filled or fully filled with reinforced concrete as per structural requirement. Experimental studies and research in Australia, China and India have shown that GFRG panels, suitably filled with plain reinforced concrete possesses substantial strength to act not only as load bearing elements but also as shear wall, capable of resisting lateral loads due to earthquake and wind. GFRG panel can also be used advantageously as in-fills (nonload bearing) in combination with RCC framed columns and beams (conventional framed construction of multi-storey building) without any restriction on number of stories micro-beams and RCC screed (acting on T-beam) can be used as floor/ roof slab. Grade and Type- GFRG panel may be supplied in any of the following three grades : 3) 4) 5)

1

Class 1- Water Resistant grade – panels that may be used for external walls, in wet areas and/or as floor and wall formwork for concrete filling; Class 2 – General grade -- panels that may be used structurally or non-structurally in dry areas. These panels are generally unsuitable for use as wall or floor formwork; and Class 3 – Partition grade – panels that may only be used as nonstructural internal partition walls in dry areas only.

ASSESSMENT Scope of Assessment Scope of assessment included conformance of manufactured panel to the specified requirements for use in building construction as: i) Load bearing wall panel ii) Shear Wall iii) Floor/ roof slab Basis of Assessment Assessment of the suitably of panels manufactured at FRBL, Cochin as load bearing wall, shear wall, floor/ roof slab is based on vii) Satisfactory test results of testing of the samples drawn from manufacturing line of FRBL plant for dimensions, weight, compressive strength, water absorption, flexural strength and fire resistant vis-à-vis requirements contained in the specification for Glass fiber Reinforced Gypsum Building Panel. viii) Construction of the two room single apartment using the panels as wall unit and roof slabs construction. ix) GFRG/Rapidwall Building structural Design Manual, developed by IIT, Madras. x) Quality Assurance scheme followed by the Certificate holder for process control. xi) Construction Manual for Building using GFRG/ Rapidwall Panels. USE OF THE GFRG PANELS AND LIMITATION The panel may be used generally in the following ways: 1) As lightweight load bearing walling in building (single or double storey construction) up to two storey construction: the panel may be used with or without non-structural core filling such as insulation, sand polyurethane or lightweight concrete. 2) As high capacity vertical and shear load bearing structural walling in multi-storey construction: the panel core shall be filled with reinforced concrete suitably designed to resist the combined effect of lateral and gravity loading. 3) As partition infill wall in multi-storey framed building: Panel may also be filled suitably. 4) As Horizontal floor/ roof slabs with reinforced concrete micro beams and screed (T-beam action) 5) As pitched (sloped) roofing 6) As cladding for industrial building 7) As compound wall 2

Special Aspects of use:

1)

2) 3)

4)

The building to be constructed using GFRG panel manufactured in accordance with the specifications prescribed in this PAC shall be designed by Competent Structural Engineers on the basis of GFRG/ Rapidwall Building Structural Design Manual, developed by IIT, Madras. It is advisable to get design of important projects vetted by IIT Madras initially on mutually agreed terms. Plumbing and Electrical services shall be governed by the provisions and details given in the Construction Manual developed by the manufacturer. GFRG building systems should be constructed only with technical support or supervision by qualified engineers and builders, based on structural designs carried out to comply with prevailing standards; this is applicable even for low-rise and affordable mass housing to provide safety of structures. It is strongly recommended that structural engineers and building designers associated with GFRG panel construction should be thoroughly familiar with the various structural aspects outlined in the Design Manual. It is also recommended that Architects and Constructions Engineers who undertake GFRG/ Rapidwall building design and Construction gain familiarity with the properties and materials, characteristic of GFRG and its application and construction system.

Limitation of Use: i) Cannot be used for wall with circular or higher curvature ii) Clear span shall be limited to 5m for residential buildings, for non residential buildings, the span shall be limited to as specified in Designs Manual.

Scope of Inspection – Scope of inspection included the verification of production, performance and testing facilities at the factory including competence of technical personnel and status of quality assurance in the factory.

3

TECHNICAL SPECIFICATIONS Raw Materials (i) Phosphogypsum – Shall be > 90% purity as CaSO4 (ii) Glass Roving – E glass shall be > 98% purity (iii) Ammonium Carbonate – Shall be of 99.14% purity as NH4CO3

Manufacturing process Phosphogypsum which is a byproduct of phosphoric acid plant is 0 calcined in calciner at 140-150 C at the rate of 15MT/hr of calcined plaster. This calcined plaster is stored in product silo having capacity of 250MT. The plaster is then transferred to batch hopper by screw conveyors and through Entoleter in wall panel manufacturing area. This area consists of 6 casting tables having dimensions of 3m x 12m, one crab having mixer and glass roving delivery system is for delivering slurry and glass roving for three tables. The chemicals are added in water & mixed and then plaster is added & mixed to form slurry. One layer of slurry is laid on the table by the crab followed by a layer of glass roving. This glass roving is embedded in to the slurry with the help of screen roller. Another layer of slurry is poured followed by a layer of glass roving this layer is pushed inside the ribs with the help of temping bar. Finally a layer of glass roving is laid for the top face of the wall panel. After getting final Gilmore wall panel is lifted from the casting table to ACROBA frame and shifted to dryer for drying. The wall O panel is dried at a temperature of 275 C for 60 minutes. After drying, the wall panel is either shifted to storage area or on the cutting table. The wall panel is cut as per dimensions supplied by the consumer and the cut pieces are transferred to stillages which are specially made for transporting wall panel. The liquid effluent generated during manufacturing process is recycled back in the system for manufacturing of new wall panels. The solid waste which is generated while manufacturing wall panels is recycled back to the calciner after crushing and separating plaster & glass roving in recycle plant. The above system is a batch process. Six wall panels can be manufactured in eight hour shift per table. Similarly, 36 wall panels can be manufactured in eight hour shift with 6 tables. Flow diagram of the system showing the manufacturing process is attached herewith.

The above system is a batch process. Six wall panels can be manufactured in eight hour shift per table. Similarly, 36 wall panels can be manufactured in eight hour shift with 6 tables. Flow diagram of the system showing the manufacturing process is attached herewith. Inspections & Testing are done at appropriate stages of manufacturing process. The inspected panels are stored & packed to ensure that no damage occurs during transportation. Construction & workmanship

(i)

Rapidwall for rapid construction Building shall be designed on the basis of Design Manual* by a qualified structural Engineer. As per the building plan and design, each wall panel shall be cut at the factory using an automated cutting saw. Door/window/ventilator and `openings for AC unit etc. shall also be cut and panels for every floor marked as per the building drawing. Panels are vertically loaded at the factory on stillages for transportation to the construction site on trucks. The stillages shall be placed at the construction site close to the foundation for erection using crane with required boom length for construction of low, medium and high rise buildings. Panels shall be erected over the RCC plinth beam and concrete is infilled from top. All the panels shall be erected as per the building plan by following the notation. Each panel shall be erected level and plumb and shall be supported by lateral props to keep the panel in level, plumb and secure in position. Embedded RCC lintels shall be provided wherever required by cutting open external flange. Reinforcement for lintels and RCC sunshades shall be provided with required shuttering and support.

(ii)

Concrete infill After inserting vertical steel reinforcement as per the structural design and clamps for wall corners are in place to keep the wall panels in perfect position, concrete having 12mm aggregate shall be poured from the top into the cavities using a small hose to go down at least 1.5 to 2m into the cavities for directly pumping the concrete from ready mixed concrete truck. For small building

construction, concrete can be poured manually using a funnel. Filling the panels with concrete shall be done in three layers of 1m height with an interval of 1 hour between each layer. There is no need to use vibrator because gravitational pressure acts to self compact the concrete inside the water tight cavities. (iii)

Embedded RCC tie beam all around at each floor/roof slab level An embedded RCC tie beam is provided at each floor slab level as an essential requirement, web portion to required beam depth at top shall be cut and removed for placing horizontal reinforcement with stirrups and then concrete to be filled.

(iv)

GFRG panel for floor/roof slab in combination with RCC GFRG panel for floor/roof slab shall be cut to required size and marked with notation. First, wall joints, other cavities and horizontal RCC tie beams are in-filled with concrete; then wooden plank 0.3 to 0.45m wide shall be provided to room span between the walls with support wherever embedded micro beams are there and then roof panels shall be lifted by crane. Each roof panel shall be placed over the wall in such a way that there will be a gap of at least 40mm. This is to enable vertical rods to be placed continuously from floor to floor and provide monolithic RCC frame within Rapidwall. Wherever embedded micro-beams are there, top flanges of roof panel shall be cut leaving at least 25mm projection. Reinforcement and weld mesh is placed for micro beams and then concrete shall be poured for micro beams and RCC slab.

(v)

Erection of wall panel and floor slab for upper floor Vertical reinforcement of floor below shall be provided with extra length so as to protrude to 0.45m to serve as start up rods and lap length for upper floor. Once the wall panels are erected on the upper floor, vertical reinforcement rods, door/window frames fixed and RCC lintels shall be casted. Then concrete where required and joints shall be filled. Thereafter, RCC tie beams all around shall be concreted.

(vi)

Water proofing The PAC holder shall provide to the client details of water proofing treatment required at different levels of construction such as foundation, sunshade and flooring etc.

(vii)

Finishing work Once concreting of ground floor roof slab is completed, wooden

th

planks with support slabs shall be removed after 4 day. Finishing of internal walls and ceiling corners shall be done using wall putty by experienced POP plasterers. Simultaneously, electrical work, water supply and sanitary work, floor tiling, mosaic or marble works, staircase work etc. shall also be carried out for each upper floor. INSTALLATION . GFRG panel erection –Methods of erection of GFRG Panel shall vary depending upon the use of the panels recommended. The method of erection of the panel is as follows: 1) Align the wall by marking with chalk line, where wall is to be erected. 2) Then fix the hold fast (regular door frame hold fast of 150mm) by plumbing wall. Two nos. of hold fasts are required for each panel. 3) Simultaneously cut the pocket of electrical points & electrical conduits to be inserted inside cavity of Rapid wall. 4) Then erect the panel by supporting with props. 5) Fix electrical switch boxes. 6) Fix other panels same as per the above method up to required length 7) Check the plumb & line of the wall. 8) Fill the holdfast gap with concrete. 9) Finish the joints of two panels by fixing fiber tape with stucco as follow: i) Make a slot of 8mm wide & 2mm deep at the joint of Rapid wall. ii) Fix the jointing fiber tape and finish the surface with stucco. 10) Joints of Rapid wall with RCC column/ beam shall be finished by stucco with reinforcing fiber of used cement bags. 11) Finish the gap around electrical points and between Rapid wall & slab/beam by stucco. Maintenance requirements A proper maintenance guide is provided by all manufacturing companies to the client. When building is to be repainted with fresh coat of paint after scraping existing paint, check for joint sealant, pipe joint, sun shade etc. and carry out required maintenance and apply primer before paint is applied.

ENT PROCEDURE

Tests done in independent laboratory S.No. Parameters

Test Method

1.

BMBA PC3:2011

6.

Dimensions Length Height Thickness Water Content Weight Water absorption Compressive strength Flexural strength

7.

Fire resistance

2. 3. 4. 5.

Clause 10.4.2 Clause 10.4.3 Clause 10.4.4 Clause 10.4.5 Clause 10.4.6 Clause 10.4.7/10.4.8 Clause 10.4.10

Requirement

Results Obtained

12.02m 3.05m 124mm Less than 1% 2 40 kg/m Max. 5% by weight Min. 160 kN/m Min. 2.1 kN/m

Within specified tolerances

4 hr rating withstood o 700-1000 C

Satisfactory 2 44.10 kg/m 1.51% (Avg.) 164.50 kN/m (Avg.) 2.158 kN /m (Avg.) Satisfactory

Chapter 5

Standards & Norms by

BUILDING MATERIALS & TECHNOLOGY PROMOTION COUNCIL For India

QUALITY ASSURANCE PLAN FOR GFRG PANEL S.No. Parameters to Requirement Specified Test Method be inspected A. Rapidwall/GFRG Panel 1. Visual Shall be free from defects like As per BMBA Appearance cracks, corrugations, ripples, PC-3:2011 stains, pockmarks, loose corners Clause10.4.1 etc. 2. Overall Length & height shall be within Clause10.4.2 Dimensional tolerance limit of ±3mm & Tolerances thickness +3mm to 0mm 3. External Skin Shall be ± 3mm (General /Water Clause10.4.2 thickness resistance grade) tolerance Min 8mm Partition grade 4. Internal Rib Shall be ± 2mm (General /Water Clause10.4.2 thickness resistance grade) tolerance Shall be ± 5mm (Partition grade) 5. Cavity Width & Shall be ± 3mm (General / Water Clause10.4.2 Depth Tolerance resistance grade) Shall be ± 7mm (Partition grade) 6. Unevenness Shall be less than 1mm (Side A) Clause10.4.2 Shall be less than 3mm (Side B) 7. Panel weight Shall be 40 Kg/m² ± 6% (Class 1 & 2) Clause10.4.4 Shall be 40 Kg/mm²±15% (Class 3) 8. Water Content Shall be less than 1% (measured Clause 10.4.3 immediately after drying process) 9. Water Shall be less than 5% by weight Clause 10.4.5 Absorption Rate (after 24 hrs of immersion in water) 10. Vertical Load Shall be more than160 kN/m bearing capacity (General / Water resistance Clause 10.4.6 (Compressive grade) strength) Shall be more than 90 kN/m (Partition grade) 11. Out of plane Shall be more than 2.1kN/m Flexural capacity (General /Water resistance Clause 10.4.7/ (Flexural grade) Clause 10.4.8 strength) Shall be more than1.3 kN/m (Partition grade) 12. “ U” Value Shall be 2.85W/M² C IS3346:1980 13. Thermal Shall be 0.617 W/m C IS3346:1980 Conductivity (K) 14.

Sound transmission

Shall be 40 (STC)

ISO 140-3:1996

Frequency of Testing Once in every ten panels Once in every fifty panels Once in every fifty panels Once in every fifty panels Once in every fifty panels Once in every fifty panels Once in every fifty panels Once in every fifty panels Once in every fifty panels Once in every fifty panels

Once in every fifty panels

Once in a year or when the composition changes and initially at the time of approval

15.

Durability i.wetting & drying ii. Salt spray

16.

Fire Resistance

Average compressive strength shall not be less than 7.52 2 N/mm Shall not suffer any apparent damage after 20 cycles Shall withstand 700-10000C

Clause10.4.9

Clause10.4.10

Once in a year or when the composition changes and initially at the time of approval

after 4hr 1.

B. Raw Materials Calcined Gypsum

2.

Ammonium Carbonate

3. 4. 5.

Glass Roving BS-94 M Retarder D-50

i.Shall be more than 90% as Calcium Sulphate ii. Combined moisture shall not be more than 6.2% Shall not be less than 99.14% as purity

As per Company Standard

i.Once in a day ii. Once in a shift

As per Once on delivery at Company site Standard These raw materials are performance based. Test Certificates provided by the manufacturers are verified at the time of delivery.

BMTPC Specification for Glass Fibre Reinforced Gypsum Building Panel

Table of Contents 1. 2. 3. 4.

5. 6. 7.

8. 9. 10.

SCOPE....................................................................................................

23 23 APPLICATION .................................................................................................. 23 REFERENCED DOCUMENTS ........................................................................ 23 DEFINITIONS .................................................................................................. 4.1. 23 STANDARD GFRG PANEL ......................................................................... 4.2. WATER RESISTANT GFRG PANEL ............................................................. 24 4.3. 24 EXTERNAL SKIN ........................................................................................ 4.4. 24 INTERNAL RIB ........................................................................................... 4.5. 25 CAVITY .................................................................................................... 4.6. 25 PANEL LENGTH ......................................................................................... 4.7. 25 PANEL THICKNESS .................................................................................... 4.8. 25 PANEL HEIGHT .......................................................................................... 4.9. 25 A AND B SIDE ........................................................................................... 25 GRADE CLASSIFICATION ............................................................................. 25 STANDARD DIMENSIONS ............................................................................. 6.1. 26 PRODUCT CODING ............................................................................... PERFORMANCE REQUIREMENTS ............................................................. 26 APPEARANCE 7.1. 26 REQUIREMENT ..................................................................... DIMENSIONAL 7.2. 26 TOLERANCES ...................................................................... 7.3. 27 WATER CONTENT ..................................................................................... 7.4. 28 PANEL WEIGHT ......................................................................................... 7.5. 28 WATER ABSORPTION RATE ........................................................................ 7.6. VERTICAL LOAD BEARING CAPACITY ........................................................ 28 7.7. OUT-OF-PLANE FLEXURAL CAPACITY ........................................................ 28 28 MARKING .................................................................................................... QUALITY SYSTEM AND QUALITY CONTROL PROCEDURES .............. 29 QUALITY PROCEDURE BY STATISTICAL SAMPLING........................... 29 10.1. GENERAL .................................................................................................. 29 10.2. SAMPLING ................................................................................................. 29 10.2.1. Sampling for Routine Tests ......................................................... 29 10.2.2. Sampling for Flexural Tests ......................................................... 31 CRITERIA OF 10.3. COMPLIANCE ......................................................................... 31 10.4. TEST METHODS ......................................................................................... 32 10.4.1. Appearance Inspection................................................................. 32 10.4.2. Measurement of Dimensions and Flatness ................................... 32 32 10.4.2.1 Apparatus ......................................................................

11.

10.4.2.2 Measurements ............................................................... 32 10.4.3. Measurement of Water Content ................................................... 33 10.4.3.1 Apparatus ...................................................................... 33 10.4.3.2 Test procedure ............................................................... 34 10.4.3.3 Calculation of Results ................................................... 34 10.4.4. Measurement of Density .............................................................. 34 10.4.4.1 Apparatus ...................................................................... 34 10.4.4.2 Test procedure ............................................................... 34 10.4.4.3 Calculation of Results ................................................... 34 10.4.5. Measurement of Water Absorption Rate ....................................... 35 10.4.5.1 Apparatus ...................................................................... 35 10.4.5.2 Test procedure ................................................................ 35 10.4.5.3 Calculation of Results ................................................... 35 10.4.6. Measurement of Vertical Load-bearing Capacity ........................ 35 10.4.6.1 Apparatus ...................................................................... 36 10.4.6.2 Test procedure ................................................................ 36 10.4.6.3 Calculation of results ..................................................... 36 10.4.7. Flexural Bending Test .................................................................. 36 10.4.7.1 Apparatus ...................................................................... 37 10.4.7.2 Test procedure ................................................................ 38 10.4.7.3 Calculation of results ..................................................... 38 10.4.8. Alternative Flexural Bending Test ............................................... 39 10.4.8.1 Apparatus ...................................................................... 40 10.4.8.2 Test procedure ................................................................ 40 10.4.8.3 Calculation of results ..................................................... 41 10.4.9 Durability Test ........................................................................... 41 10.4.9.1 Wetting and drying test .................................................. 41 10.4.9.2 Salt spray test ................................................................. 41 10.4.10 Fire Resistance Test ..................................................................... 41 10.5. TEST REPORT ............................................................................................ 42 CUTTING, HANDLING, STORAGE AND DELIVERY ................................ 42 11.1. CUTTING .................................................................................................. 42 11.2. HANDLING ................................................................................................ 42 11.3. STACKING ................................................................................................. 42 11.4. PROTECTION FROM WEATHER .................................................................... 43 11.5. DELIVERY ................................................................................................. 43

Specifications for Glass Fibre Reinforced Gypsum (GFRG) Building Panel 1 SCOPE This document forms the product specification for manufactured GFRG panels designed for use in the construction industry for walling, ceilings, suspended floor formwork and partitions. The specified technical and mechanical property requirements refer to the finished product, that is, the final manufactured GFRG panel dried and ready for installation. Specified also is the quality control procedure and the associated mechanical tests necessary to ensure an acceptable quality of the finished GFRG panel product. 2 APPLICATION This specification is intended for use by licensed manufacturers of GFRG to ensure a uniform, quality controlled global product suitable for its intended purpose. The details of this document also assists the end users, such as engineers, architects and builders, ® both in their designs using GFRG and in specifying the physical properties of the GFRG panel in their contract documents. 3 REFERENCED DOCUMENTS The following documents are referred to in this specification: Report by IIT, Madras on Testing of GFRG panel dt29th March,2012 GFRG/Rapidwall Building Structural Design Manual,IIT Madras ISO 9004.1 Quality Management and Quality System Elements, Part 1:Guidelines; 4 DEFINITIONS For the purpose of this specification the following definitions apply: 4.1 Standard GFRG Panel GFRG panel is a factory manufactured walling product used in the construction industry to provide habitable enclosures for residential, commercial and industrial buildings. The 124mm thick hollow-core panels are machine-made using formulated gypsum-plaster reinforced with chopped glass-fibre. A typical cross-section and isotropic view of the wall panel is shown in Fig.1.

Length

External skin

124

Thickness

Internal rib

Glass fibre

15

Gypsum plaster

15

Cavity

(a) Cross-section

Fig.1 Standard GFRG panel

Water Resistant GFRG Panel panels in Water resistant GFRG panels are the same as ordinary GFRG appearance. However the ingredients of the water resistant GFRG are modified specifically, to provide water resistance when used externally or in wet areas such as bathrooms or laundries, etc. External Skin The two 13mm thick faces making up the panel are collectively defined as external skins as shown in Fig.1. Internal Rib The 20mm thick ribs inside the panel connecting the two external skins are called internal ribs as shown in Fig.1.

Cavity The internal hollow cores inside the panel are called the cavity as shown in Fig.1. Panel Length The panel length is the maximum horizontal dimension of a single wall without vertical joint as indicated in Fig.1. Panel Thickness The panel thickness is the distance between the external faces of the two external skins, as shown in Fig.1. Panel Height The panel height is the maximum vertical dimension of a single wall without a horizontal joint. A and B Side The smoother side of the GFRG panel cast against the machine bed in the manufacturing process is called the A side. The B side is screeded and is relatively rougher than A side. GRADE CLASSIFICATION GFRG panel is supplied in three grade classifications:1). Class 1 - Water Resistant grade – panels that can be used for external walls, in wet areas and/or as floor and wall formwork for concrete filling; 2). Class 2 - General grade – GFRG panels that can be used structurally or nonstructurally in dry areas. These panels are generally unsuitable for use as wall or floor formwork; and 3). Class 3 - Partition grade – GFRG panels that can only be used as non-structural internal partition walls in dry only areas. STANDARD DIMENSIONS The current nominal manufactured dimensions of each GFRG panel are: • Length 12,020 mm • Height 3050 mm, and • Thickness 124 mm

Product Coding GFRG panels are coded using the following convention:GFRG

TS-

L×H

× D ate and place of manufacture Panel height Panel length Panel thickness & classification R registered Trademark

Where panel type is indicated as ‘G’ for general grade, ‘W’ for water resistant grade or ‘P’ for partition grade. For example a Wat er resist ant l grade panel made in RCF, Tro mbay p st lant in Chembur , Mumbai 21 Feb 2010 is coded as: - GFRG 124G-12X321FEB10/TROMBAY

PERFORMANCE REQUIREMENTS Appearance The two external faces of GFRG panels should be free from defects such as corrugations, ripples, pockmarks, stains, loose corners, cracks or any other defects which would adversely affect a painted decorative surface finishes. It is a requirement that paint can be directly applied to the A-side of GFRG without the need for extensive rendering or plastering. The quality of finish on the B-side of the panel can be controlled by the operation of the final screeding in the manufacturing process. The ap pear ance r equ ir ement s o n the B -side ar e u sua lly d ecid ed t hro ugh negotiation between the manufacturer and its client. However, the minimum requirements for the Bside are that a 3.5mm texture coating or a trowelled-on coating will cover all the defects. 7.2

Dimensional Tolerances

The manufactured dimensional tolerances for a full sized GFRG panel shall satisfy Tables 1 and 2:Table 1. Overall Dimensional Tolerance Length Height Thickness Nominal length Nominal height Nominal thickness ±3mm ±3mm +3 to –0 mm Table 2 Cross-sectional Dimensional Tolerance External Skin Internal Rib Panel Classification Cavity Width Thickness Thickness General Grade Nominal Nominal Nominal & Thickness Thickness Width Water Resistant ±3 ±2 ±4 Grade Nominal Nominal Partition Grade Minimum 8 Thickness Width ±5 ±7

Cavity Depth Nominal Depth ±3 Nominal Depth ±7

The flatness of the panel shall satisfy the following: • The maximum local unevenness of protruding or recessing belessthan1mmon the A side and 3mm on the B side, as shown in Fig.2(a); and • For the overall curvature of the surface the deviation of any point on the panel face from a 2.5m straight edge shall not exceed k=3mm in any part of the panel and in both of the two orthogonal directions, as shown in Fig.2(b)&(c).

Rapidwall® panel

δ

δ

(a) Local unevenness 12020mm FULL PANEL 48 CAVITY CELLS

3050

STRAIGHT EDGE STRAIGHT EDGE (b) Measurement of curvature in both directions 2.5m

κ

Straight edge ®

GFRG panel (c) Overall curvature Fig. 2 Measurement of flatness

Water Content The water content of panels measured immediately after the drying process (without moisture intake after drying) shall be less than 1% when tested in accordance with Clause 10.4.3. The maximum acceptable water content after production is referred to in Section 7.5.

Panel Weight The weight of the dried and empty hollow core GFRG panel shall satisfy Table 3:Table 3 Empty Panel Weight Panel Classification (mm) Class 1, 124 mm thick Class 2, 124 mm thick Class 3, 124 mm thick

Nominal Weight 2 (kg/m ) 40 40 40

Tolerance % ±6% ±6% ±15%

7.5 Water Absorption Rate The water absorption rate for water resistant grade GFRG panels shall not be greater than 5% by weight after 24 hours of immersion in water when tested in accordance with Clause 10.4.5. No test is needed for other grades of GFRG panels. 7.6 Vertical Load Bearing Capacity When tested in accordance with Clause 10.4.6, the cross-sectional compression strength of the panel shall satisfy the minimum requirements as given in Table 4. Table 4 Acceptance criteria for compression strength Minimum compression strength (kN/m) General or water resistant grade 160

Partition grade 90

Out-of-Plane Flexural Capacity When tested in accordance with Clause 10.4.7 or 10.4.8, the out-of-plane flexural strength of the panel shall satisfy the minimum requirements as given in Table 5. Table 5 Acceptance criteria for flexural strength Minimum Flexural Strength per meter width General or Water Partition Grade Resistant Grade 2.1 kNm 1.3 kNm MARKING Each manufactured GFRG panel shall be clearly marked with the following particulars: • Product code in accordance with Clause 6.1; • The manufacturer’s name, address and trademark; • Quality checked mark and identification of the checker; and • Signs for packaging and transportation.

QUALITY SYSTEM AND QUALITY CONTROL PROCEDURES Quality of the finished product is assured by a proper quality control system, it is needed to demonstrate the compliance with this specification and to supply products that conform to the full requirements of this specification. Generally, one of the following four quality procedures shall be adopted:• • •

Evaluation by means of statistical sampling; The use of a product certification scheme; Assurance using the acceptability of quality system; and

• For reference a procedure for statistical sampling is provided in Clause 10 of this specification. QUALITY PROCEDURE BY STATISTICAL SAMPLING General Sampling and the establishment of a sampling plan should be carried out in accordance with Clause 10.2 Sampling

Sampling for Routine Tests Three GFRG panels should be randomly selected from a batch of panels for tests described in Sections10.4.1to10.4.6. Grouping of panels to form a batch shall follow the following rules: 1). Every 500 panels of same grade classification form a batch, when there is no variation in mix design, ingredient materials, manufacturing conditions, and dryer conditions; 2). Two different grade classifications i s into two different batches even when the number of panels in a batch is less than 500; 3). When the ingredients of gypsum, glass fibre, water and any other additives changes, new batch should be formed whenever such a change takes place. The same principal of forming a different batch applies when any other change is made in the manufacturing and drying process such as change of recipes or any other activity that may affect the property or quality of the finished panels; and 4). When significant variations exist in the manufacturing process that may affect the quality or properties of the panels, such as significant variation in the quality of plaster, batch is formed with a much smaller number of panels depending on the magnitude and extent of variations. Forming batch is on daily (or shift) basis in such kind of situations, i.e. panels produced in the same day (or shift) are considered as a batch. Three test sample plates (520×580) are to be cut from each selected panel. The positions for cutting these three test plates are shown in Fig.3. Two different test specimens are to be cut from each test plate in accordance with the layout of Fig.4. The specimens shall be machine cut to the dimensions with a tolerance of not more than ±2mm.

Positions for cross-sectional dimension check 12020 1000 500 580 3050

500 520 5750 580 1075 500

Flexural test sample Routine test sample plates Positions for crosssectional dimension check

Fig.3 Positions of sampling

520mm

Compression test specimen520×250

Ribs

250mm

Water content test by drying oven and Water absorption test specimen 250×300

5 80mm 300mm 250mm

Fig.4 Detailed dimensions of test specimens

520 500

10.2.2. Sampling for Flexural Tests The flexural strength of a panel largely depends on the quality, quantity and distribution of the glass-fibers in the panel. The flexural strength test may be conducted over a much longer interval and when any variation (such as quality, quantity or distribution) in glass-fibre takes place in the manufacturing process. One set of flexural tests consisting of three test specimens shall be conducted on one cluster of panels. Panels are grouped as one cluster if they are: 1). Made in the same six-month period of time when nothing changes in the manufacturing process; or 2). Made with a same batch of glass fiber. When an old batch of glass-fibre is used up and a new batch of glass-fibre is used for production, the panels made with new batch of glass fiber are considered as a new cluster. Any other change that is made to the glass fiber such as change of supply source, change of brand, change of quantity or quality of glass fiber, change of fiber strand length and means of distributing fiber, etc. shall make a different cluster of panel. The three test specimens shall be cut from three different panels selected randomly from the same cluster. Specimen shall be cut at least one meter away from the vertical sides of the panel and shall be cut in such a way as shown in Fig.3 and Fig.5. ribs 125

Test specimen

250

1000

250

250 125

2850 or 3050

Fig. 5 Plan view of flexural test specimen Criteria of Compliance The batch or cluster of panels is deemed to satisfy the performance requirements of Clause 7 if all the test specimens selected in accordance with Clause 10.2 pass all the tests described in Clause 10.4. Otherwise it is considered to be non-compliant. Panels that do not comply with the requirements for partition grade must not be used for building purposes and shall be destroyed. Panels that do not satisfy the general grade or water resistant grade may be downgraded to partition grade if they pass the specification for partition grade. It is generally recommended that the samples be representative of the quality of all the panels in the same batch or cluster. In other words, the whole patch or cluster of panel fails the quality check and cannot be used if the samples fail any of the tests of Clause 10.4. However, if it is judged that the failed sample does not represent the quality of the whole batch of panel, and the manufacturer intends to use some or any panel in that batch

or cluster, then all the tests in Clause 10.4 shall be repeated to that batch or cluster such that the quality of the panels are proved. An acceptable way of repeated tests is that the number of test panels is doubled and all the repeated tests pass the performance requirements. Only the panels that pass all the quality checks can be marked as quality checked. Test Methods Laboratories that undertake the tests shall generally satisfy AS ISO/IEC17025-1999: General Requirements for the Competence of Testing and Calibration Laboratories. Test equipment and devices shall satisfy the relevant requirements and be calibrated regularly to a local or international standard.

Appearance Inspection Every finished panel shall be visually inspected in accordance with Clause 7.1.

Measurement of Dimensions and Flatness The overall and cross-sectional dimensions as well as flatness shall be measured from the selected test panel (selected in accordance with Clause 10.2.1) to satisfy Clause 7.2 in any part of the panel. Apparatus The tools used for measurements shall satisfy the following requirements:1). The overall panel dimensions of length, height and thickness shall be measured to accuracy within 1.0mm; and 2). The other dimensions shall be measured to within 0.5mm. Measurement

The length of the panel shall be measured at the positions of 1d, 2e and 3f; and the height of the panel shall be measured at the positions of a4, b5 and c6, as shown in Fig.6a. The thickness of the panel shall be measured at the 12 positions of 1 to 6 and a to f. As shown in Fig.3, the cross-sectional dimensions shall be measured at six different positions of a, b, c, 4, 5, and 6, as shown in Fig.6a. Six separate measurements shall be taken at each of the above six positions, as shown in Fig.6b. The flatness shall be checked at the positions of a2a22, a22b2, b2b22, b22c2, a4, b5 and c6.

a 1 2 3

a1 a2 a3

b a11

b1

a22

b2

a33

b3

4 1000

c b11 b22 b33

5 5000

c1

500

350

1000

1000

d

c2

or

e

c3

1000

1000

550

500

f

6 5000

1000

(a) Positions of overall dimension measurements

(b) Cross-sectional measurement points Fig.6 Dimensional measurements

Measurement of Water Content The water content shall be tested for the selected panels against Clause 7.3. Sampling of the test specimen shall be made in accordance with Clause 10.2.1. Do not treat the edges and surfaces of the specimens nor damage the specimens. This test measures the loss of water of the specimen after drying in a standard oven. It is combined with the measurement of density and water absorption tests. Should the samples after conditioning take up moisture then the panel was over cooked (calcined) in the dryer and fails the test. 10.4.3.1 Apparatus

Air circulating oven: The net space available inside the drying oven shall not be less than 200×300×360. The oven shall have a temperature control at 40±2°C and a humidity control at 50±2%. Balance or scale: with a capacity of 5kg and an accuracy of 0.5g.

Test Procedure

1). Weigh each original specimen and record their weights; 2). Condition the specimen (or specimens) to constant weights, within 0.1% of the dried weight, at a temperature of 40±2°C, in an atmosphere having a relative humidity of 50±2%. This can be done by drying the specimen for 24 hours initially and weighing the specimen; then drying for another 4 hours each time and weighing the specimen until the difference of the two consecutive weights of the specimen is with 0.1% of the dried weight; and 3). Weigh the dried weight w of each specimen to within 0.5g. Calculation of Results

The weight loss of the individual specimen in percent with respect to its dried weight w is the water content of the specimen.

Measurement of Density Density of the panel shall be measured from the specimens immediately after the water content tests and before water absorption tests. Care shall be taken to prevent damaging the specimens in the measurement so that it does not affect the water absorption test. Apparatus

Right-angle ruler: with an accuracy of within 1 mm. Test procedure

Take the following measurements from each specimen:•The four dimensions as shown in Fig.7 measured to within 1mm, where H1 and H2 are the lengths of the two vertical sides, respectively, and B1 and B2 are the horizontal dimensions that is perpendicular to the vertical side measured with a right-angle ruler. B1 Rib H1

H2

B1

Fig.7 Dimensions for density measurement Calculation of results

The density ρ (weight per surface area) of a specimen is calculated by w

ρ=

H1 + H 2 × B1 + B2 2 2 where w is the weight of the specimen measured at step 3 of 10.4.3.2 and dimensions H1, H2, B1 and B2 are shown in Fig.7.

10.4.5. Measurement of Water Absorption Rate The specimens tested for density is immediately used for water absorption rate. Apparatus

Balance: same as 10.4.3.1. Water bath or container: enough room to immerse the three specimens and keep them separated and elevated from the bottom of the bath with minimum spaces of 25mm. Test procedure

1). Immerse the specimens flat in a bath of water at a constant temperature of 21±0.5°C with a head of 25 mm of water over the top of the sample. The sample should be positioned in the water bath elevated one inch above its base; 2). Remove the specimens from the bath after 24 hours of immersion, wipe excess water from the surfaces and edges of the specimens and weigh immediately to within 0.5g. Calculation of results

The percentage of weight gain with respect to the dried weight of each specimen calculated is the water absorption rate.

Measurement of Vertical Load-bearing Capacity The test specimen as sampled in accordance with Clause 10.2.1 is shown in Fig.8 and the test set up is shown in Fig.9, where a universal compression test machine shall be used. 520

120 Typ.

13

20

Fig.8 Cross-section of compression test specimen Compression load

Platen of compression machine

Specimen 250

B

Thin layer of quicksetting plaster to ensure a firm contact with platen

Fig.9 Compression test set up (Elevation)

Apparatus

Universal compression machine: the test machine shall be calibrated Test procedure

1). Measurement of Dimension – the width B of the test specimen is measured at the waist of the specimen as shown in Fig.9. The measurement shall be taken on both the front face and the back face of the specimen and an average value used; 2). Placing of Specimen – the test specimen shall be placed at the centre of the platen on the test machine. Under no circumstance should any part of the specimen be placed outside the perimeter of the platen of the test machine; 3). Capping-the top and bottom faces of the test specimen shall be capped with a thin layer of quick-setting plaster (such as dental paste) to ensure firm and uniform contact with the platen. The strength of the applied plaster shall not be lower than that of the test specimen at the time of testing; 4). Loading – Apply the compression load gradually in a rate not greater than 10kN per minute until it reaches the peak load and then drops at least 20% off the peak load. The maximum applied load (peak load) F indicated by the testing machine shall be recorded. Calculation of results

The unit strength of a specimen is reported as p =

F

in a unit of kN/m, where F is B the peak load, in kilo newtons, and B is the width in meter at the waist of the specimen.

Flexural Bending Test The flexural test set up is shown in Fig.10.

L/3

L/3

L/3

Load F from loading jack Main Steel beam Pin support Secondary Steel beam

Roller support

Test specimen Pin support

Displacement measurement L=2500mm

Fig.10 Flexural test set up

124 Roller support

Apparatus

As the specimen is one meter wide, it is important for the load and reaction force from the supports to be distributed evenly along the width of the specimen. The point load from a load jack is applied to a main distribution beam that then distributes the load equally to two secondary distribution beams. The load is finally transmitted from the secondary distribution beams to the top face of the test specimen as an evenly distributed line load. The minimum ultimate flexural strength of the main distribution beam shall be 10kNm. The secondary distribution beam shall be 1000mm long with a minimum flexural 11 2 rigidity EI of 5×10 N/mm . To ensure a good contact and even distribution of load, a thin layer of quick-setting plaster (such as dental paste) shall be applied between the bottom face of the secondary beams and the contact surface of the specimen. The specimen shall be supported firmly with one pin support and one roller support as illustrated in Fig.11. The pin support is composed of two steel plates of 1000mm long×100mm wide × minimum10mm thick and a 1m long steel roller bar with a minimum diameter of 30mm. The steel bar is fixed to the bottom plate (such as by welding) and the top plate just sit on top of the bar to ensure free rotation. The roller support shown in Fig.11(b) is similar to the pin support except that some smaller steel roller bars of about 10mm diameter and 1000mm long are provided underneath the bottom steel plate to ensure both free rotation and longitudinal movement. The loading jack shall have a minimum load capacity of 20kN. The displacement transducer shall have a minimum travel distance of 100mm. The measurement or data acquisition involves both the applied load measured from the load cell and displacement from the displacement transducer at the mid-span. The accuracy of measurements shall be within 0.1kN for load and 0.5mm for displacement. For tests in China, guidelines for the test apparatus and methodology shall follow GB 50152-92: National standard for tests of concrete structures. Test procedure

1). Mark the positions of support line (centre line position of the roller bar) on the bottom of the specimen, and load line (centre line position of the secondary distribution beam) on the top of the test specimen; 2). Set up the pin and roller supports; 3). Apply a thin layer of quick-setting plaster on top of the supporting steel plates and then place the test specimen on top of the two supports. Waite a few minutes for the plaster to set; 4). Apply a layer quick-setting plaster on top of the test specimen at the position of the secondary distribution beams and place the secondary distribution beams in position. Allow the plaster to set; 5). Set up the rest of the loading system (main distribution beam and its support, etc.) and loading jack; 6). Place the displacement transducer under the test specimen at the mid-span. A piece of small plate (about 20mm×20mm×2mmthick) shall be glued onto the tip of the transducer to prevent it from going into a crack if the crack happens to occur at the position of the displacement measurement point;

7). Load the jack under displacement control in a strain rate of not greater than 5mm/minute until the load passes the peak and drops at least 50% off its peak load; 8). In the mean time of applying loading, record the test data at sufficient number of test points to produce a load vs. displacement curve (as illustrated in Fig.12). An automatic data acquisition system is recommended that can record the complete test curve automatically. If manual record is used, one data point (a pair of load and displacement readings) shall be taken at a displacement increment of not more than 1.5mm. Calculation of results

The maximum moment capacity of a specimen is given by M u = 1 wL2 + 1 (F + S)× L 8 6 Where 2 w = the unit weight of the panel which is typically 0.4kN/m ; F = the first peak load from the load vs. displacement curve as explained in more detail below, in kN; S = the weight of the load distribution system including the main and secondary distribution beams, in kN; and L = the span which is 2.5m. The first peak load is the applied load at which the first major crack occurs (usually accompanied with a clear sound of breaking). Two typical cases to identify the first peak load are illustrated in Fig.12. This first peak load may not be the maximum load as shown in Fig.12(b).

Total load F(kN)

6

First peak

5 4 3 2 1 0 0

10

20 Mid-span deflection

30

40

F(kN)

(a)

8 7 6

First peak

4

Total

load

5 3 2

0

1 0

10

20

30

40

50

60

70

Mid-span deflection (b) Fig.12. Typical out-of-plane bending test results

Alternative Flexural Bending Test When the test frame and equipment required for the test as described in Section 10.4.7 are not available, the test provided in this section can be used as an alternative for the flexural bending test. The test set up is shown in Fig.13. Blocks of weight are used as load in this test instead of a loading jack.

Total weight F One column of weight. Minimum 7 columns along span

Gap between columns minimum 50 Layer 2 Layer 1

Test specimen

120 Roller support

Pin support L=2500mm

Fig.13 Alternative flexural test set up Apparatus

The supporting systems of the test specimen and the displacement measurement transducer are the same as that described in Section 10.4.7. All the weight blocks shall have an equal size and weight and be calibrated to an accuracy of within ±1.0% of the weight. The maximum weight of each block is generally required to be less than 10kg in order to have enough number of blocks to provide an even distribution of load on top of the specimen (in an area of 2500×1000), unless it can be shown that the heavier blocks will not adversely affect the even distribution of load. The size of the blocks shall also be restricted such that at least 7 columns of weight with a minimum gap of 50mm between columns can be distributed evenly along the span of the specimen, as shown in Fig.13. For tests in China, guidelines for the weights can be found in GB 50152-92. Test procedure

1). Mark the positions of support line (centre line position of the roller bar) on the bottom of the specimen; 2). Set up the pin and roller supports; 3). Apply a thin layer of quick-setting plaster on top of the supporting steel plates and then place the test specimen on top of the two supports. Waite a few minutes for the plaster to set; 4). Place the displacement transducer under the test specimen at the mid-span. A piece of small plate (about 20mm×20mm×2mmthick) shall be glued onto the tip of the transducer to prevent it from going into a crack if the crack happens to occur at the position of the displacement measurement point; 5). Put the weight blocks row by row, column by column and layer by layer on to the specimen as shown in Fig.13, starting from the mid span of the specimen and ensuring the even distribution of weights on the whole surface area of 2500×1000; 6). In the mean time of applying loading, record the test data at sufficient number of test points to produce a load vs. displacement curve (as illustrated in Fig.12). One

data point (a pair of load and displacement readings) shall be taken at a displacement increment of not more than 1.5mm. Calculation of results

The maximum moment capacity of a specimen is given by 2

Mu = 1 (w + f)L 8 Where 2 w = the unit weight of the panel which is typically 0.4kN/m ; f = F/L, F in kN is the first peak load (total weight) from the load vs. displacement curve as explained in Section 10.4.7.3; and L = the span which is 2.5m. The first peak load may not occur exactly at a time when a whole layer of load is applied. In that case, the load distribution at failure is not uniform and the maximum moment shall be calculated based on the actual distribution of the load. Durability Test Wetting and drying test 0

Put the panels through 20 cycles of wetting and drying at room temperature of 30 C. Each cycle consist of 24 hours of wetting followed by 24 hours of drying. Measure the average compressive strength at the end of 20 cycles. Salt spray test

Embed a 12mm dia,250mm reinforcing rod in the concrete filled in cavity. After 7 days curing, hung the same in a salt spray chamber for 2 weeks. Observe any apparent damage to the panel and to the reinforcement. Fire Resistance test The fire resistance test on GFRG panel (Rapidwall) shall be conducted using a blow torch (burning kerosene as fuel). The blue flame temperature shall be measured and shall be in 0 0 the range of 700 C to 1000 C. The blower tip of the blow torch shall be kept at a distance of about 50 mm from one face of the building panel (size 300 x 300 x 124 mm) so that the blue flame shall directly hit the panel continuously. The panel shall be exposed to such a state for continuation duration of 4 hours. The other face of the panel shall be pasted with a thermocouple to monitor the temperature continuously. 0

Record the temperatures ( C) at 30 minutes interval during the test period of 4 hours for the hollow GFRG panel and the GFRG panel filled with M20 concrete the results. At the end of the test, no damage or cracks should be observed beyond the spot where he flame was directly hitting the face of the panel.

CUTTING, HANDLING, STORAGE AND DELIVERY This part of specification is only applicable within the factory before delivering to end-users. For the transport and storage of panel outside the factory, reference shall be made to specification for transport, storage and installation. Cutting Cutting shall be made with specific machine and impact tools such as hammer shall not be used for cutting or removing part of the panel. All cutting shall be made in accordance with the drawings and requirements provided by the client. Generally the following requirements are applicable: 1). Tolerance to be ±1mm; 2). Openings to be partially cut in the factory, leaving about 100mm at the corner to be cut after installation of the panel; 3). Damage to corners shall be limited to within 10mm×10mm; and 4). Metal closure studs (C channels) are fitted to the edges of a panel immediately after cutting. Handling Handling of panel shall be made with specific machinery. Movement of panel shall be reasonably slow and care shall be taken to prevent undue sagging, cracking or damage to the panel especially at the sides, edges and corners. The damaged panel or part of the panel must not be used and shall be removed and destroyed. The RBS Friction Lifting Jaws must not be used in the factory as every rib in the GFRG panel can be clamped only once. Stacking GFRG panels shall be neatly stacked to avoid panel distortion, damage or moisture ingress. This can be achieved by stacking vertically on support extending the full length of the panel or a firm, clean and flat surface not susceptible to moisture. It shall also be kept free of any dirt, oil or other foreign matter. When vertically stacked in open air, panels shall be protected from collapse caused by strong wind. A good practice is stacking panels inside a Stillage with its stabiliser legs extended. Protection from Weather All panels shall be kept dry preferably by being stored inside a building and under cover. Where it is necessary to store the panels outside, it shall be stacked off the ground in accordance. Delivery GFRG panels are usually packed and loaded on specifically designed stillage and delivered by suitable trucks. Extreme care must be taken in loading, transportation and unloading to ensure the safety and protection of the panels from damage due to collision or collapse of the panels. Care shall be exercised to avoid exceeding the maximum allowable height of vehicles applicable to a specific road in a specific area. All general grade panels shall be protected from rain with a plastic membrane. Protection from rain for water resistant grade panels is generally not required.

Chapter 5

Structural Tests Results  Conducted by IIT ­ MADRAS

STUDIES ON THE BEHAVIOR OF GLASS FIBER REINFORCED GYPSUM WALL PANELS

Glass fiber reinforced gypsum (GFRG) wall panel is made essentially of gypsum plaster reinforced with glass fibers. The panels are hollow and can be used as load bearing walls. The hollow cores inside the walls can be filled with in-situ plain or reinforced concrete. This paper presents guidelines for the use of GFRG wall panel as a lateral load resisting component in buildings based on a numerical analysis procedure to arrive at its capacity estimation under axial compression, compression with inplane bending and shear. Variation of buckling load of unfilled GFRG wall panels for various widths is reported. The axial load carrying capacity of 1.02 m wide and 2.85 m high wall panel, obtained from the numerical analysis and the test results are comparable for this load case. While assessing the axial load capacity for design under compression, a minimum possible eccentricity (causing out-ofplane bending) is accounted for. An engineering model is proposed to assess the strength of unfilled and concrete filled GFRG wall panels in multi-storied building system subjected to lateral load such as earthquake. Introduction In a high seismic intensity zone, resistance of buildings to earthquakes is often ensured by adopting structural systems where seismic actions are assigned to structural walls (shear walls), designed for horizontal forces and gravity loads while columns and beams are designed only for gravity loads. Structural walls provide a nearly optimum means of achieving the important objectives, viz., strength, stiffness and ductility. Buildings braced by structural walls _______________________________________________________

1

Ph D Research Scholar, 2 Professor, Structural Engineering Division, Department of Civil Engineering, Indian Institute of Technology Madras, Chennai 600 036, India.

are invariably stiffer than framed structures, reducing the possibility of excessive deformations under small earthquakes. The necessary strength to avoid structural damage under moderate earthquakes can be achieved by properly detailed longitudinal and transverse reinforcement. Special detailing measures need to be adopted to achieve, dependable ductile response under major earthquakes (Paulay and Priestley, 1992). Glass fiber reinforced gypsum (GFRG) wall, a new composite wall product known as ® ® Rapidwall /Gypcrete in the industry, is made essentially of gypsum plaster, reinforced with chopped glass fibers. The glass fibers about 300 – 350 mm long are randomly distributed inside 2 the panel skins and ribs in the manufacturing process. The fiber content is 0.8 kg/m . The 120 mm thick panels are hollow and can be filled with in-situ plain or reinforced concrete to increase the strength. A typical cross section of the panel is illustrated in the Fig. 1.

Length

94mm

Thickness = 120mm

250mm

20mm thick web Gypsum Plaster 13mm thick flange

230mm Reinforcement by chopped glass fibers

Figure 1. Cross section of GFRG wall panel Wu and Dare (2004) have carried out axial and shear load tests on GFRG wall panels of standard 2.85 m height. The width of panel specimens was 1.02 m for axial load tests, 1.52 m and 2.02 m for shear load tests. They have reported that under axial load, unfilled GFRG wall panels failed due to plaster crushing, irrespective of the eccentricity of axial load. The concrete filled specimens all failed due to buckling and flexural tensile breaking of the GFRG walls. The failure load was governed by the eccentricity and support conditions. The compressive strength of unfilled wall panels was governed by the plaster strength and that of concrete filled panels was governed by out-of-plane buckling. The axial load carrying capacity of concrete filled wall panels was only affected by the axial load eccentricity and support conditions. The failure mode for shear load specimens of concrete filled walls was due to the longitudinal tearing of the GFRG panels, which is very different from the failure mode of a traditional RC wall. As a result, the shear strength is governed by the strength of the GFRG panels and was not affected by the

strength of the concrete infill. Typical shear failure modes for unfilled panels and concrete filled panels are shown in the Fig. 2.

(a) Unfilled panel – Diagonal cracks

(b) Unfilled panel – End crushing

(c) Concrete filled panel – Vertical cracking

Figure 2. Typical failure modes for GFRG wall panels subjected to shear (Wu and Dare, 2004) Wu (2004) has reported that there are two types of shear failure modes in a building constructed with GFRG walls. The first mode is the shear failure of the panel itself, and the second is shear sliding at the interface of a wall and the floor slab. The continuity of longitudinal reinforcement at the horizontal joint may affect the shear strength of both the failure modes. Mechanical properties of the GFRG panel, as reported by Wu and Dare (2004) are shown in Table 1. Axial load capacity of wall panels against buckling are estimated and shown in the Table 2 and the in-plane lateral load buckling capacity is shown in Table 5. It is found that the Poisson’s ratio of the wall panel is approximately equal to 0.2 from experimental results. The modulus of elasticity of the panel considered is 3000 MPa. Estimation of GFRG Wall Panel Capacities In the present study an attempt is made to estimate for design purposes the capacities of GFRG wall panels under (i) Axial loads, (ii) Axial load with out-of-plane bending (iii) Out-ofPlane bending capacity (iv) Axial load and in-plane bending moment and (v) Capacity of wall panel due to shear load.

Table 1. Mechanical Properties of GFRG Building Panel (Wu and Dare 2004) Mechanical Property Unit Weight Uni-axial Compressive Strength Uni-axial Tensile Strength Elastic Modulus Coefficient of Thermal Expansion Water Absorption Thermal Resistance Sound transmission coefficient Fire Resistance Level

Characteristic Value 2 40 kg/m 160 kN/m 35 kN/m 3000 – 6000 MPa

Remarks Unfilled Single leaf GFRG Panel.

12 x 10-6 mm/mm/ 0C

< 5% 2

0.36 m K/W 28 45 >3h

By weight after 24 h of immersion Unfilled Panel Unfilled panel Concrete filled panel For Structural adequacy

Axial Load Capacity While assessing the axial load carrying capacity of the wall panels a minimum eccentricity causing out of plane bending is accounted for. As per standards such as IS 456 (2000), the design of reinforced concrete walls should take into account the actual eccentricity of the vertical force subjected to a minimum value of 0.05 times the wall thickness t (6 mm for t = 120 mm). According to masonry design codes such as IS 1905 (1987), the design of a wall shall consider appropriate eccentricity, which in no case shall be taken to be less than t/24 (5 mm for t = 120 mm). In the case of wall panels supporting floor slabs from one side, the eccentricity to be considered should be more than the minimum values indicated above. It is recommended that a value of minimum eccentricity equal to t/6 (20mm for t = 120 mm) shall be considered conservatively. Additional value of eccentricity may be considered when the out of plane bending is explicitly involved. The characteristic values of axial compressive strength of GFRG wall panels are obtained from the compression test results on 2.85 m full height panel subjected to eccentric loading. In general, it is conservative to assume pinned-pinned condition as shown in Fig. 3. It may be noted that for design purposes, the characteristic values should be divided by partial safety factor 1.7. Finite element analysis of the wall panel, using plate-shell elements to model both flanges and webs, was carried using the SAP 2000 NL software. These numerical analysis results are compared in Table 2 with the experimental results reported by Wu and Dare (2004). It is seen that the numerical results are comparable with the experimental results for the 1.02 m panel. The axial load carrying capacity of the unfilled GFRG panels of widths 1.52 m and 2.02 m, estimated by finite element analysis are also shown in the Table 2.

Table 2. Axial Load Carrying Capacity of Unfilled GFRG Wall Panels Width of

Numerical analysis Results (kN)

Experimental Results** (kN)

Panel (m)

e=0

e = 20 mm

e=0

e = 20 mm

158.1 230.1 300.0

132.4 – 166.7 – –

119.6 – 166.7 – –

e = 6mm (Minimum) 168.7 252.4 319.6

1.02 173.7 1.52 245.3 2.02 328.7 e = Eccentricity ** Wu and Dare (2004)

P e

2850 mm

Figure 3. Experimental set- up for Pinned-Pinned panels The same finite element model was used to estimate the elastic critical buckling load of the wall panel, and the results are listed in Table 3 for different widths of the wall panel. These results indicate values much higher than those shown in Table 2, confirming that buckling is not a likely mode of failure, as evidenced by the testing (which showed crushing of plaster). Table 3. Buckling Load Values When the Wall is Subjected to only Axial Load Width of GFRG Wall Panel (m) 1.02 1.52 2.02

Buckling Load Pcr (kN) 622 926 1233

Out-of-Plane Bending Capacity The out- of-plane flexural strength of 120 mm thick GFRG wall panel without filling is shown in Table 4. From the test results, it is found that filling without reinforcement does not improve the out-of-plane moment capacity of the panel. Table 4. Out-of-plane flexural capacity of Unfilled / Concrete filled Panel without Steel Reinforcement Property Out-of-plane moment capacity (kNm / m)

Ribs parallel to span

Ribs perpendicular to span

2.1

0.88

In-Plane Bending Capacity GFRG wall panels can be used as load bearing walls in multi storied buildings capable of resisting fairly large lateral load. Each wall can act as a shear wall resisting vertical load, inplane bending and shear. Invariably, such a wall shall be infilled with reinforced concrete. The following simplified procedure may be used to calculate the ultimate in-plane flexural strength of concrete filled GFRG wall panel. 6) Assess

the stress distribution along the cross section of the wall panel based on linear elastic assumption. σ  P M y (1) A I

2. Based on the stress distribution from the Eq. 1, there are two different cases to be considered. (a). The whole cross section is under compression or there is no tensile stress in the cross section (σ ≥ 0) compare the maximum value of ‘ σ’ in the cross section with the compressive strength of wall panels given in Table 1. If the calculated stress is less than the design compressive strength of the wall, the design is safe otherwise redesign is required. (b) If tension exists in the cross section (σ < 0) go to step 3. The unfilled and concrete filled GFRG wall panel without continuous reinforcement in the cores is not able to transmit tension between floors, therefore case (b) is not applicable to unfilled or concrete filled GFRG wall panel without continuous longitudinal reinforcement.

xii)

When tension exists in the cross section, the flexural strength can be calculated using the following assumption.

8) The contribution of the panel to ultimate strength in tension and compression is neglected and the system is treated as filled concrete with concrete effective only in compression and the reinforcement bars in tension.

9) Tension reinforcement (full length bars) are assumed to act as unbonded bars with constant stress, limited to 90 MPa in the entire tension zone (assuming lack of bond between the infilled concrete and the wall panel). The assumed stress distribution across the cross section of a GFRG wall panel is shown in Fig.4. From the test results, it has been found that there is practically no bond between concrete and GFRG wall panel. It is assumed that all reinforcing bars are subjected to same stress and that this stress is limited to the following value based on the studies in prestressed concrete section with unbonded tendons. Pu Mu

0.42xu 0.5D

D–xu xu D

T

Cu= 0.36f ckbxu xi

Figure 4. Stress Distribution across the GFRG Wall Panels under Axial Load and in-plane Bending Moment. Tensile stress in steel rod, 0.85 fck fst  70  ⎛A ⎞ 100⎜

in N/mm

⎟

st

⎜

⎝

2

(2)

⎟

bd p

⎠

Equating forces: P  0.36 f bx  f u

th

ck

u

n st

A



sti i1

(3)

where Asti is the area of the i bar located at a distance xi from the centre. Equating moments, n

M u  fst 

Asti  D / 2  xi  0.36 fck xu D / 2  0.42xu  i1

where xi is considered to be positive if it is on the tension side of the mid depth.

(4)

From the Eqs. 3 and 4, the value of xu and Asti can be determined by trial and error. Alternatively, Pu – Mu interaction curves may be generated for a given panel with infill concrete (fck) and given area of steel per cavity (Ast). Such an interaction diagram (using non-dimensional coordinates) has been generated and is shown in Fig. 5. The value of p/fck can be obtained from this diagram and the suitable bar reinforcement can be identified. It may be noted that minimum eccentricity requirement should be satisfied. 0.50 0.45 0.40 0.35

Pu /f ck bD

0.30 0.25

p/fck = 0.005

0.20

p/fck = 0.01

0.15 0.10 0.05

p/fck = 0.015 p/fck = 0.02

0.00 0

0.01

0.02

0.03 M u /f ck bD

0.04

0.05

0.06

2

Figure 5. Interaction diagram for panel subjected to axial load Pu and in-plane bending moment, Mu Shear Capacity of Panels Wu and Dare (2004) have reported that in all of the shear load tests on unfilled panels, there were visible 45° shear cracks, developed before the peak load was reached, as shown in Fig.2(a), and shear strength varies from 19.1 kN/m to 24.5 kN/m. Using strength of materials approach, the capacity of unfilled panels under shear load can be assessed as follows. ⎛ b ⎞ Capacity of unfilled panel under shear load =

2⎜

t

⎟ f

σt

⎝ cosθ ⎠

where b = Width of wall panel, θ = Inclination of crack with respect to horizontal axis, tf = Thickness of flange of the wall panel, σt = Permissible tensile strength of wall panel. This capacity works out to 39 kN/m for a GFRG panel of 1.02 m width.

Buckling Capacity under In-Plane Shear Load The possibility of buckling failure under shear loading was investigated in the present study through numerical analysis using SAP 2000 NL. The results obtained are shown in Table 5, corresponding to three widths of wall panel. The values of lateral load obtained (262 to 596 kN) are significantly higher than the capacities reported by Wu and Dare (2004). Hence it is clear that buckling mode of failure is unlikely to occur not only under axial load but also under shear loading for the unfilled GFRG wall panels. Table 5. In-Plane Buckling Capacity due to shear Load alone Width of Wall Panel (m) 1.02 1.52 2.02

Buckling Lateral Load Vcr (kN) 262 425 596

Conclusions Axial load carrying capacity of unfilled GFRG wall panels, of various widths when subjected to eccentric loads, is estimated using numerical analysis. The lateral load carrying capacity of panels is also estimated. A simplified procedure has been suggested for assessing in-plane flexural strength of concrete filled wall panels. For a given force demand, reinforcement required for a concrete filled GFRG wall panels can be obtained using interaction diagram that has been developed. Using simple approach, the capacity of unfilled panels under shear load is estimated. It is also established by comparing the results of finite element buckling analysis with the available experimental results, that failure of the GFRG wall panel does not occur due to buckling, on account of in-plane axial and shear loads, as the critical loads are much higher than the actual capacities. References IS: 456-2000, Plain and Reinforced concrete - Code of Practice, Bureau of Indian Standards, New Delhi, India. IS: 1905-1987, Code of Practice for Structural use of Unreinforced Masonry, Bureau of Indian Standards, New Delhi, India. Paulay T., and Priestley M.J.N., 1992. Seismic Design of Reinforced Concrete and Masonry Buildings, John Wiley & Sons, New York, USA. SAP 2000 NL. Structural Analysis Program (Static and Dynamic Finite Element Analysis of Structures), Computers and Structures Inc., Berkeley, CA, USA. Wu, Y.F. and Dare, M. P., 2004. “Axial and Shear Behavior of Glass Fiber Reinforced Gypsum Wall Panels: Tests”. Journal of Composites for Construction, ASCE, 8 (6): 569-578. Wu, Y. F., 2004. “The effect of longitudinal reinforcement on the cyclic shear behavior of glass fiber reinforced gypsum wall panels: Tests”. Engineering Structures, ELSEVIER, 26 (11):1633-1646.

Conclusion Rapidwall Panel provides a new method of building construction in fast track, fully utilising the benefits of prefabricated, light weight large panels with modular cavities and time tested, conventional cast-in-situ constructional use of concrete and steel reinforcement. By this process, man power, cost and time of construction is reduced. The use of scarce natural resources like river sand, water and agricultural land is significantly reduced. Rapidwall panels have reduced embodied energy and require less energy for thermo-regulation of interiors. Rapidwall buildings thereby reduce burdening of the environment and help to reduce global warming. Rapidwall use also protect the lives and properties of people as these buildings will be resistant to natural disasters like earthquakes, cyclone, fire etc. This will also contribute to achieve the goal of much needed social inclusive development due to its various benefits and advantages with affordability for low income segments also. Fast delivery of mass dwelling/ housing is very critical for reducing huge urban housing shortage in India. Rapidwall panels will help to achieve the above multiple goals.