Recent Trends in Concrete Technology

Antony Kishore.M & Ajithkumar.V B.E., IInd Year, Department Of Civil Engineering, Paavai Engineering College, Namakkal-637018, TN. E-Mail: [email protected]

ECENT ECENT TR ENDS ENDS IN CONCR ETE ETE TECHNOLOGY

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CONTENTS PAGE NO

1. 2. 3. 4. 5.

ABSTRACT INTRODUCTION CONCRETE PREPARATION OF CONCRETE RECENT TRENDS IN CONCRETE TECHNOLOGY

6. TECHNIQUES 6.1. 6.2. 6.3. 6.4. 6.5. 6.6.

RECYCLED CONCRETE FIRE TECHNOLOGY AUTOCLAVED AERATED CONCRETE DECORATIVE CONCRETE GRAFITO DÉCOR LIGHT WEIGHT CONCRETE HEAT RESISTANT REFRACTORY CONCRETE

7. EQUIPMENTS 7.1. 7.2. 7.3. 7.4. 7.5. 7.6. 7.7.

BOOM PUMP (CONCRETE PUMP) TRILAR PUMPS CONVEYOR BELTS LASER SCREEDS REDI-MIX TRUCKS CONCRETE SAWS CRANES

8. CONCLUSION 9. REFERENCES

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ABSTR ACT ACT In olden days, It was hard to make concrete structure due to hand mixing and labour  labour  requirements. From the beginning when the concrete invented by British British engineer John Smeaton in 17th century, the technology in concrete is improved day to day. The recent techniques such as Recycled concrete, Fire technology, Autoclaved aerated concrete, Grafito décor, Light weight concrete, Heat resisting refractory refra ctory concrete and latest equipments such as Boom Pump, Trilar Pumps, Conveyor Belts, Laser Screeds, Redi-Mix Trucks, Concrete Saws, Cranes are used for construction of concrete structures in this days. The improved concrete technology techniques and equipments are explained in this Paper.

INTR ODUCTION ODUCTION  Now a days, Constructions field field is the improved one. Day to day number of Industries, Colleges, Offices, Houses, Hotels, etc is increasing for man needs. When a structure is to be constructed, it is a important one, Concrete. Presently in Concrete Technology T echnology Many of  techniques such as fire technology, etc and equipments such as crane, cr ane, laser screed, etc are used to built a concrete structure. In I n this paper, the explain the details about a bout ³R ecent ecent Trends In

Concrete Technology´. Let us see the paper. CONCR ETE ETE The word concrete comes from fro m the Latin word "concretus" (meaning compact or  condensed), the perfect passive participle of "concrescere", from "con-" (together) and "crescere" (to grow). Concrete is a composite composite construction material, composed composed of cement and other  cementitious materials such as fly ash and slag cement, aggregate, water and chemical admixtures.

PR EPA EPAR ATION ATION OF CONCR ETE ETE Thorough mixing is essential for the production of uniform, high quality concrete. For  this reason, equipment and methods should be capable c apable of effectively mixing concrete materials containing the largest specified aggregate to produce uniform mixtures mixtures of o f the lowest slump  practical for the work. 2

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ECENT ECENT TR ENDS ENDS IN CONCR ETE ETE TECHNOLOGY

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There are many Techniques and  Equipments have come forward in day to day progress in concrete technology.

TECHNIQUES ECYCLED ECYCLED CONCR ETE ETE

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Recycled Concrete Material (RCM), also known as crushed concrete, is reclaimed PCC  pavement material. Primary sources of o f RCM are demolition of existing concrete pavement,  bridge structures, curb and gutter, and from central recyclers, who obtain raw feed from fro m Commercial/private facilities. This material is crushed by mechanical means into manageable fragments and stockpiled. RCM may include include small percentages of o f sub-base soil so il and related related debris. Comprised of highly angular angular conglomerates of o f crushed quality aggregate and hardened cement, RCM is rougher and more absorbent than its virgin constituents. Furthermore, differences among concrete mixes and uses result res ult in varying aggregate qualities qualities and sizes The cementitious component has a high amount of alkalinity by nature, and chlorides from deicing salts may be present-a concern in regards to steel reinforcement re inforcement corrosion. RCM may also contain aggregates susceptible to alkali-silica reactions r eactions or D-cracking.

FIR E TECHNOLOGY Fire Technology is a peer-reviewed academic acade mic journal publishing publishing scientific research dealing with the full range of actual, possible, and potential fire hazards facing humans and the environment. It publishes origin or iginal al contributions, both theoretical and empirical, that contribute to the solution of problems in fire safety s afety and related fields. It is published published by Springer S pringer in conjunction with with the National Fire Protection Association. Topics include material testing, fire modelling, detection and suppression, performance based building design, building code, emergency evacuation and human behaviour, fire investigation, wildfire and fire risk analysis.

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AUTOCLAVED AER ATED ATED CONCR ETE ETE Autoclaved aerated concrete (AAC), also known as autoclaved cellular concrete (ACC) or autoclaved lightweight concrete (ALC). ( ALC). It is a lightweight, lightweight, precast building material that simultaneously provides structure, insulation, and fire and mold resistance. resista nce. AAC products include blocks, blocks, wall wa ll panels, floor and roof panels, and lintels. It has been refined into a highly thermally ther mally insulating insulating concrete-based material used for   both internal and external construction. Besides ACC's insulating capability, one of its advantages in construction is its quick and easy e asy installation. Even though regular cement mortar can be used, 98% of the buildings erected with w ith AAC materials use thin bed mortar, which comes to deployment in a thickness of  inch. This varies according to national building codes and creates create s solid and compact building members. AAC material can be coated with a stucco compound or plaster plaster against the t he elements. Siding materials such as brick or vinyl siding siding can also be used us ed to cover the outside of o f AAC materials. AAC has been produced for more than 70 years, and it offers considerable advantages over other  construction materials, one of the most important being its very low low e nvironmental nvironmental impact. 

AAC¶s excellent thermal ther mal efficiency makes a major contribution to environmental environmental protection protect ion  by sharply reducing the need for heating and cooling in buildings.

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AAC¶s easy eas y workability workability allows accurate a ccurate cutting, which minimizes the generation of solid waste during use. Unlike other building materials, AAC can eliminate the need to be used in combination with insulation products, which which increase the t he environmental impact and cost of  construction.

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AAC¶s high resource efficiency gives it low environmental impact in all phases of its life cycle, from processing of raw materials to the disposal of AAC waste.

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AAC¶s light weight also saves energy energ y in transportation. transportation. The fact that AAC is up to five times lighter than concrete leads to significant significant reductions in CO2 emissions during transportation. In addition, many AAC manufacturers apply the principle of producing as near to their consumer markets as possible poss ible to reduce the need for transportation.

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DECOR ATIVE ATIVE CONCR ETE ETE GR AFITO AFITO DÉCOR  Decorative concrete GRAFITO GRAFIT O DECOR - universal material for finishing. Finishing materials of GRAFITO system successfully used for exterior decoration, decorat ion, and finishing finishing the interior and do not contain harmful to human health components. With decorative concrete GRAFITO DECOR there are ar e many advantages, it allows to create various structural types of finishing with stone look or a tree hi-tech, but also prevents the formation of cracks, hides imperfections and defects in the walls allows any an y color solutions. solutions. Using Us ing  polyurethane  polyurethane stamps a series of Grafito design, we can decorate the walls, columns co lumns in the texture of metal and metallic inks using a series of o f graphite design, paint texture obtained under  different types of metal. Polyurethane stamps give the necessary necessar y texture of the metal for the interior and decorative paint with pearl pigments give the color with an elegant shimmer. It may  be painting under gold, silver, red aged copper or any other version of the painting from the gallery of flowers series

LIGHT WEIGHT CONCR ETE ETE The DOE Method, used by First mix does not cover lightweight concrete and a nd needs to be modified so as to be suitable for designing mixes made with lightweight aggregate in the following respects: 

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The concrete strength is reduced by the weakness of o f the aggregate. It is unreasonable to stipulate that aggregates should be in the saturated, s aturated, surface-dry condition.

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Since the densities of the materials may vary widely, it is unreasonable to determine material proportions by weight as in the DOE Method, if in in fact it is the volumetric  proportions that are significant. The products are lightweight, making them easy to place and secure using less skilled

labour. The bricks can be sawed, sawe d, drilled and shaped like wood woo d using standard hand tools, regular  screws and nails. It is simpler than brick or concrete.

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The features of light weight concrete are, y

fro m 650 Kg/m3 to 1250 Light Weight: Blocks are lightweight having density range from Kg/m3 as compared co mpared to 1800 Kg/m3 to 2400 Kg/m3 for conventional brick and concrete respectively.

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Comprehensive Strength : Blocks are available in wide range of density from 650 Kg/m3 to 1250 Kg/m3 of average compressive co mpressive strength of 2.0 to 7.0 N/mm2.

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respect ively.. The Earthquake R esistant esistant : Blocks are lighter than concrete & brick respectively lightness of the material increases resistance against earthquake as well as less chances of  loss / damage to human lives.

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Insulation : Blocks provide superior thermal insulation properties compared to that of  conventional brick and concrete. This property of EnviroBUILD reduces the t he heating and cooling expenses.

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manufact ured with fly ash 100% recycled Environment Friendly : Blocks products are manufactured resource.

HEAT R ESISTANT ESISTANT R EF EFR ACTO ACTOR Y CONCR ETE ETE There are two ways, two types of heat resistant concretes that can be prepared. Cheaper  and more expensive-stronger and weaker. The first one is a high heat refractory concrete. This type will survive in real high heat and can be used in hot-face. Hot face is a wall facing the main heat from a source. Internal walls, floor and arches made from firebricks inside oven is hot face. Firebricks face the heat, the hot flames from wood fire and the red hot embers. Refractory concrete can be mixed with heat resistant cement, or, can be purchased ready in bags. It is different to fill holes and awkward spaces with castables. Large blocks tend to crack as a result of something called heat differences in material, or temperature differences in material in other words, which is a very powerful natural phenomena. We still have firebricks here for making the dome do me part properly.   Now, the second one heat resistant concrete type. It is a lower grade heat resisting concrete, lower grade in withstanding heat but still it can be applied successfully in many areas 6

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whose get pretty heated too. For instance layers such as those on the other side of firebricks, on the outside of firebricks, the slab under the heated floor made from fire bricks or cladding around the firebrick dome, chimney parts, etc. Into this concrete type the common Portland cement goes in and of course lime. Both lime and port land are bonding agents and are described more further below. Instead of firebrick grog we can use river sand and river stones. Sand and stones that come from river. If buying it, it's easily recognizable; what comes from river is round and it isn't sharp as opposed to the mostly crushed stuff coming to us from stone quarries, otherwise either  of them is a building material.

EQUIPMENTS

BOOM PUMP (CONCR ETE ETE PUMP) A concrete pump is a tool used for transferring liquid concrete by pumping. There are two types t ypes of  concrete pumps. The first type of concrete pump is attached attac hed to a truck. It is known as a trailer-mounted boom concrete  pump because it uses aremotecontrolled articulating robotic arm (called a boom) to place concrete with pinpoint accuracy. Boom pumps are used on most of the larger construction projects as they are capable of   pumping at very high volu volumes mes and because of o f the labour saving nature of the placing boom. They are a revolutionary alternative to truck-mounted concrete pumps. The second main type of concrete pump is either mounted on a truck and known as a truck-mounted concrete pump or placed on a trailer, and it is commonly referred to as a line  pump or trailer-mounted concrete pump. This pump requires steel or rubber concret e  placing hoses to be manually attached to the outlet of the machine. Those hoses are linked together and lead to wherever the concrete needs to t o be placed. Line pumps normally pump concrete at lower volumes than boom pumps and are used for smaller volume concrete placing p lacing applications such as swimming pools, sidewalks, and single family home concrete slabs and most ground slabs. 7

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There are also skid mounted and rail mounted concrete pumps, but these are uncommon and only used on specialized jobsites such as mines and tunnels.

TR ILA ILAR  PUMPS Although often overlooked, overlooked, this piece of o f equipment can be critical in getting gett ing the job done right. But, not all trailer pumps are created equal. A good place to start in evaluating this tool is a review of its main features²a hopper, cylinders, and a valve. Beyond these basic features, machines vary based on engine size, outlet out let and hose diameters, and other ancillary features.

Hoppers. The concrete feeds directly out of  the ready-mix truck into the hopper. Hoppers may seem standard across a line of trailer pumps. However, they can vary in shape, capacity, and reinforcement to withstand heavy concrete. Examining this versatile machine reveals a simple tool with a wide variety variet y of components to fit any pumping application. From the bottom of the hopper, the concrete concret e is sucked into one of o f two cylinders located  beneath the engine. The concrete is then forced out of the cylinder, by way of a valve, into the hose where it eventually finds its way to the far end for placement into forms, block block walls, wa lls, or  slabs.

Cylinders. Cylinder diameter, cylinder length, and strokes per minute go into calculating the output of the machine. Cylinder diameter diameter frequently is larger than t han the outlet and hose diameter, so there is a reduction in the diameter of o f the slug of concrete going through the pump, which results in increased pressure. And pumps that can overcome overco me greater pressure are able a ble to  pump concrete farther. Some manufacturers opt for larger cylinders cylinders and shorter stroke lengths, making up for the increased pressure pres sure by supplying larger engines.

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CONVEYOR  BELTS A conveyor belt consists of two or more pulleys, with a continuous loop of material. One or both of the pulleys are powered, moving the belt and the material on the belt forward. The  powered pulley is called the drive pulley while the unpowered pulley is called the idler. The belt consists of one or more layers of  material they can be made out of rubber. Many belts in general material handling have two layers. An under  layer of material to provide linear strength stre ngth and shape called a carcass carca ss and an over layer called the cover. The carcass is often o ften a cotton or plastic web or mesh. The cover is often various rubber or plastic compounds specified by use of the belt. Covers can be made from more exotic materials for  unusual applications such as silicone for heat or gum rubber when traction is essential. There are two main industrial classes of o f belt conveyors; conveyors; Those in general material handling such as those moving boxes along inside a factory and bulk material handling such as those used to transport industrial and agricultural materials, such as grain, coal, ores, etc. generally in outdoor locations. Generally companies providing general material handling type  belt conveyors do not provide provide the conveyors for bulk materi al handling. In addition addition there are a number of commercial applications of belt conveyors such as those in grocery grocer y stores. Material flowing over the belt may be weighed in transit using a belt weigher. Belts with regularly spaced partitions, are used for transporting transporting loose materials up steep inclines. Belt Conveyors are used in self-unloading bulk freighters and in live bottom trucks. Conveyor  technology is also used in conveyor transport such as moving moving sidewalks or escalators, as well as on many manufacturing assembly lines. Stores often have conveyor belts at the check-out c heck-out counter to move shopping items. items. Ski areas also use conveyor belts to transport skiers up the hill. A wide variety of related conveying machines are available, different as regards principle of operation, means and direction of conveyance, including screw conveyors, vibrating conveyors, conveyors, pneumatic conveyors, con veyors, the moving floor system, which uses reciprocating slats to move cargo, and roller conveyor sys s ystem, tem, which uses a series of powered rollers ro llers to convey boxes or pallets.

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LASER  SCR EEDS EEDS The Laser Screed is a self-propelled self-propelled four wheel drive, four wheel steer unit. Each model has a telescoping boom boo m and interchangeable head. The Screed has an automatic laser control system s ystem that ensures an accurate level finish through through the use of  electro-hydraulic controls. Laser receivers mounted at each end of the screed head receive rec eive a signal from a transmitter multiple times per second providing totally automatic control to finished floor level. A single laser transmitter t ransmitter controls up to 1000 ft (or greater depending upon model) enabling the screeds to work to a tolerance of 3mm or better. Concrete is discharged in strips to match the size of o f the machine approximately 1" higher  than final grade. The Laser Screed Scr eed moves into position and the telescopic boom extended over  the discharged concrete. The screeding / compacting head is then lowered to the grade established by the laserlaser level transmitter. Retraction of the boom causes the screed head to be drawn across the fresh concrete which is leveled and compacted in a single pass. Once a pass is completed, the machine machine is repositioned to the right with some overlap on o n the previously screeded concrete. The operation is repeated, ensuring optimum finished level tolerances are attained across the whole w hole floor area. The screed head itself consists of o f 3 parts: the  plow, the auger, and the vibrator. The plow p low disperses the concrete evenly, the auger removes the excess material to finished grade, and the vibrator smoothes the surface. In situations where floor design specifies a dryshake applied surface hardener the Laser Screed's method of operation is matched matc hed in terms of speed and working method by the Topping Spreader, resulting in automatic concrete screeding and dry-shake application. Providi Pro viding ng industry with maximum productivity while maintaining consistent levels of quality. qua lity. 10 | P a g e

EDI-MIX EDI-MIX TR UCKS UCKS

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Special concrete transport trucks are made to transport and mix concrete up to the t he construction site. They can be charged with dry materials and water, with the mixing occurring during transport. With this process, the material has already been mixing. The concrete mixing transport truck  maintains the material's liquid state through t hrough agitation, agitation, or  turning of the drum, until delivery. The interior of the drum on a concrete mixing truck is fitted with a spiral blade. In one rotational direction, the concrete is pushed deeper into the drum. This is the direction the drum is rotated while the concrete is being transported to the building site. This is known as "charging" the mixer. When the drum rotates in the other direction direct ion,, the Archimedes' Archimedes ' screw-type arrangement arrangement "discharges", or forces the t he concrete out of the drum. From there it may go onto chutes to guide the viscous concrete directly to the job site. The drum is traditionally made of steel but on some newer trucks as a weight reduction measure, fiberglass has been used.

CONCR ETE ETE SAWS A concrete saw is a power tool used for cutting concrete, masonry, brick, asphalt, tile, and other ot her solid materials. It can be a small hand-held cut-off saw, a big walk-behind saw or other styles, and it may be powered by gasoline, hydraulic or pneumatic pressure, or electric motors. The saw blades used on concrete saws are often diamond saw blades to cut concrete, asphalt, stone, etc. The significant friction generated in cutting hard substances like concrete usually requires the blades to be cooled to prolong their life and reduce dust. Stones, rocks, sands and clays can contain large amounts of crystalline silica and are used to make kerbs, flags, bricks, tiles and concrete. Cutting these materials produces airborne dust containing very fine respirable crystalline silica (RCS) particles. These part icles are small and it is not always possible to see the RCS dust in normal lighting. Serious S erious health effects, such as 11 | P a g e

lung cancer or silicosis, can result from exposure to RCS. This is because fine RCS R CS particles can  penetrate deep into the lungs. These are following ways to reduce or control the dust: 1. Wet cutting with adequate water w ater supply. 2. If possible, use diamond saw blades instead of abrasive wheels to cut. Diam D iamond ond saw blades normally cut more quickly than abrasive wheels, and need less water. 3. The concrete saw should have a local exhaust e xhaust ventilation ventilation (LEV) system, which can ccapture apture the majority of dust emitted during the cutting operation. operat ion. 4. When operating, the operator should always wear the t he  personal protective equipment.

CR ANES ANES A crane, can also be known as a bridge crane, overhead crane is a type of machine used for lifting, generally equipped with a hoist (wire rope drum), wire ropes or chain sand sheaves, that can be used u sed both to lift and lower materials and to move them horizontally. It uses one or  more simple machines like a hoist to create mechanical advantage and thus move loads beyond the normal capability of a human. Cranes are commonly employed in the transport industry industry for the loading loading and unloading of  freight, in the construction industry for the movement of materials and in the manufacturing industry for the assembling of heavy equipment. Modern cranes usually use internal combustion engines or electric motors and hydraulic h ydraulic systems to provide a much greater lifting capability than was  previously possible, although manual cranes are still utilised where the provision of power would be uneconomic. unecono mic. Cranes exist in an enormous variety of forms ± each tailored to a specific use. Sometimes Sizes range from the smallest jib cranes, used inside workshops, to the tallest tower  cranes, used for constructing high buildings. buildings. For a while, mini - cranes are also used for  constructing high buildings, buildings, in order to facilitate facilitat e constructions by reaching tight spaces 12 | P a g e

CONCLUSION Thus the trends in concrete technology are improved by the above techniques and equipments. Even though few drawbacks drawbacks are there t here which can be solved or prevented.

EFE EFER ENCES ENCES

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1. Text book of ³Concrete Technology´ by P.D.Kulkarni 2. www.wikipedia.com 3. www.scribd.com 4. The Indian Concrete Journal 5. Text book of  ³Constructions Techniques, Equipments and practices´  by Dr.P.Purushothama Dr.P.Purushothama raj ra j

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