CHAPTER – I INTRODUCTION
The econom economy y of a region region and its transp transport ort infrast infrastruc ructur turee are closely closely interinterrelated. Hyderabad is the capital of Indian state of Andhra Pradesh. The city has an area of 650 square kilometres with a population of 6.8 million, and the metropolitan area contains 7.7 million residents, making it the fourth most populous city and the sixth most populous urban agglomeration in the country.
The city was expanded in 2007 to form the Greater Hyderabad Municipal Corpo Corporati ration. on. As a growin growing g metrop metropoli olitan tan city city in a develo developin ping g countr country, y, Hydera Hyderabad bad confronts confronts substantial substantial urban pollution, pollution, traffic congestion, congestion, overpopul overpopulation ation and other logistic and socio-economic problems. Public transport system should be the soul of a city. The presence of a good public public transport transport system can deliver deliver better environmenta environmentall conditions conditions,, faster speeds of travel, travel, better better mobility mobility and economic economic growth. The existing existing public transport in Hyderabad mainly comprises bus system exclusively operated by the the State run Andhra Pradesh Road Transport Corporation (APSRTC).Hyderabad Metro Rail is all set to bring to the citizens, an internationa internationall urban transportati transportation on experience through through its quality-int quality-intensive ensive,, comfort comfort & safety oriented features. The emphasis emphasis of this report is explaining the various steps involved in laying the foundation for Hyderabad Metro Rail.
1
Fig: 1.1 ROUTE MAP SHOWING THREE CORRIDORS OF HYDERABAD METRO RAIL
2
Fig: 1.1 ROUTE MAP SHOWING THREE CORRIDORS OF HYDERABAD METRO RAIL
2
Table 1.1 : Different Different corridors of metro rail
Stage 1:
Nagole to Mettiguda (8.2 Km)
Stage 2:
Miyapur to S R Nagar (11.55 Km)
Stage 3:
Mettiguda to Begumpet (7.83 Km)
Stage 4:
Begumpet to Shilparamam (11.37 Km)
Stage 5:
S R Nagar to LB Nagar (17.75 Km)
Stage 6:
JBS to Falakunama (15.43 Km) .
3
CHAPTER – II
SCOPE OF THE PROJECT
Hyde Hyderab rabad ad is a metro metropo poli litan tan city city that that cove covers rs 625 625 sq. sq. km. km. of muni munici cipa pall corporation area and 6852sq. km. of metropolitan area. It is fast emerging as the hub of IT/ITES, Biotech, Pharmacy and Tourism sector. Its strategic geographical location, multilingual and cosmopolitan culture, tremendous growth potential and investmentfriendl friendly y econom economic ic policy policy are all making making it an attract attractive ive destin destinatio ation n for corpor corporate, ate, entrepreneurs, academicians and homemakers alike.
Currently, over 2.8 million personalized vehicles ply on Hyderabad roads, with an additio addition n of 0.20 0.20 million million vehicles vehicles every every year. year.
8 million million motorized motorized trips trips are are made made
ever every y day, day, of whic which, h, only only abou aboutt 3.36 3.36 mill millio ion n or 42%a 42%are re made made by the the Publ Public ic Transportation System (PTS) i.e., buses and local trains. That means the rest of the trips are made by personal vehicles leading to traffic bottlenecks, high pollution levels and a steep increase increase in fuel consumption. consumption. A people-friend people-friendly ly city is that which provides provides a good quality of life. An efficient, safe, reliable and comfortable public transportation system is one of the pre-requisites of good living. The solution lies in Mass Rapid Transit System (MRTS). Accordingly, the development of Metro Rail was approved for 71.16 km., covering three high density traffic corridors of Hyderabad.
4
CHAPTER – III
OBJECTIVES OF THE PROJECT
The Metro Rail System has proved to be the most efficient in terms of energy consumptio consumption, n, space occupancy occupancy and numbers transported. transported. Hi-capacity Hi-capacity carriers – very high volumes of peak hour peak direction trips. Eco-friendly – causes no air pollution, much much lesser lesser sound pollut pollution ion..
Greater Greater traffic traffic capacity capacity – carries carries as much much traffic traffic as
7 lan lanes of bus bus traf traffi ficc or 24 lan lanes of car car traf traffi ficc (eit (eith her way way). Low ener energy gy consumption – 20% per passenger km in comparison to road-based systems. Very low ground ground space space occupa occupatio tion n – 2 meters width width only for elevated elevated rail. Faster Faster – reduce reducess journey time by 50% to 75%. 75%.
5
CHAPTER – IV FOUNDATION A foundation is the lowest and supporting layer of a structure. Foundations are generally divided into two categories: • •
Shallow foundations. Deep foundations
.
4.1
SHALLOW FOUNDATIONS:
Shallow foundations, often called footings, are usually embedded about a meter or so into soil. One common type is the spread footing which consists of strips or pads of concrete (or other materials) which extend below the frost line and transfer the weight from walls and columns to the soil or bedrock. Another common type of shallow foundation is the slab-on-grade foundation where the weight of the building is transferred to the soil through a concrete slab placed at the surface. Slab-on-grade foundations can be reinforced mat slabs, which range from 25 cm to several meters thick, depending on the size of the building, or post-tensioned slabs, which are typically at least 20cm for houses, and thicker for heavier structures . 4.2
DEEP FOUNDATIONS:
A deep foundation is used to transfer the load of a structure down through the upper weak layer of topsoil to the stronger layer of subsoil below. There are different types of deep footings including impact driven piles, drilled shafts, caissons, helical piles, and earth stabilized columns. The naming conventions for different types of footings vary between different engineers. Historically, piles were wood, later steel, reinforced concrete, and pre-tensioned concrete. Foundations are designed to have an adequate load capacity with limited settlement by a geotechnical engineer, and the footing itself is designed structurally by a structural engineer. The primary design concerns are settlement and bearing capacity. When considering settlement, total settlement and differential settlement is normally considered. Differential settlement is when one part of a foundation settles more than another part. This can cause problems to the structure the foundation is supporting. It is necessary that a foundation not be loaded beyond its bearing capacity or the foundation will "fail". 6
CHAPTER – V SOIL INVESTIGATION
Soil investigation is the foremost method adopted in any project before raising the structure. Based on the reports of soil investigation, foundation location is decided. The results of the report gives the details about the nature of soil, bearing capacity of soil, type of footing to be adopted and also the excavation depth required for footing etc.
STANDARD PENETRATION TEST:
The soil exploration method adopted during the soil investigation is the standard penetration test. The standard penetration test (SPT) is an in-situ dynamic penetration test designed to provide information on the geotechnical engineering properties of the soil. The main purpose of the test is to provide an indication of the relative density of granular deposits, such as sands and gravels from which it is virtually impossible to obtain undisturbed samples. The great merit of the test and the main reason for its widespread use is that it is simple and inexpensive. The soil strength parameters which can be inferred are approximate, but may give a useful guide in ground conditions where it may not be possible to obtain borehole samples of adequate quality like gravels, sands, silts, clay containing sand or gravel and weak rock. In conditions where the quality of the undisturbed sample is suspect, e.g. very silty or very sandy clays, or hard clays, it is often advantageous to alternate the sampling with standard penetration tests to check the strength.
5.1 SOIL PROFILE IN HYDERABAD:
In general the sub soil profile at Hyderabad metro rail project consists of filled up soil (road crest) up to 0.9m, which is underlain by silty sand / clayey sand up to 3.0 m. This silty sand/clayey sand layer is further underlain by residual soil / completely weathered rock.For excavation purpose, safe slope is analyzed for different depths i.e., 2.5m to 3.5m using TALREN software. Surcharge of 18 kpa is considered for analysis. Sub soil properties considered for analysis are given in the following table. 7
Minimum factor of safety is considered greater than 1, since the slope is temporary. Square footings and sloped footings were planned for designing for the piers as per the soil conditions and bearing capacities. They are categorized into different types with certain changes in dimensions, as type A, type B, type C and so on.
Fig 5.1 Soil exploration
8
Fig 5.2 Extracting the sample
9
CHAPTER – VI
CODES REFFERED FOR PROJECT
•
IS: 1786:1985-High strength deformed steel bars and wires for concrete reinforcement specifications.
•
IS: 2502:1963-code of practice for bending and bar fixing for concrete reinforcement.
•
IS SP: 34-1987-Detailing on concrete reinforcement.
•
MOSRT&H-Specifications for road and bridge works.
•
IS 10262-2009-Guidelines on concrete mix proportioning.
•
CWP for survey
•
CWP for fixing permanent barricades.
•
CWP for concrete production and transportation .
10
CHAPTER – VII
STAGE RESPONSIBILITIES
7.1
7.2
STAGE INCHARGE:
•
Reports are sent to the corridor in charge.
•
Plans and resources are arranged.
•
Design department and site execution team are liaison
•
Responsible for safety and quality procedures.
•
Monitoring the program vs. progress and achievement as per the target.
•
System implementation.
CONSTRUCTION MANAGER: Reports are sent to the stage in charge.
•
Co-ordinates with administrative help.
all
concern
•
Involve in preparation of construction work procedure.
•
Takes initiatives to obtain the statutory permits from GHMC and Traffic Police
•
Arrange resources (such as specialized agency for foundation construction, machine, tools, area lighting, and consumable materials).
•
Monitors utilization of machinery/ equipment.
•
Involves in safety and quality pep talks.
•
Monitors the program vs. progress of work and analyses issues, critical path if any as per set target.
•
Monitors requirements of safety and work environment.
11
departments
for
technical
and
7.3
7.4
7.5
CONSTRUCTION ENGINEER:
•
Reports of day to day activities are sent to the constructive manager.
•
Interacts with LTMRHL representatives and generates RFLs for inspection.
•
Execute the job through specialized agency and give the feedback about the progress to construction manager.
•
Interfacing with internal departments like planning, quality, plant and machinery, safety and stores for operation of activities.
•
Preparation of the BBS.
•
Ensures to implement safety requirements.
•
Responsible for resources.
•
Submits the requirements of materials and other resources for the purpose of work to the construction manager.
•
Checking of reinforcements fixing, shuttering alignment and verticality, concrete placing and compaction, de shuttering and post concrete activities like curing.
•
Prepares the work schedule based on project schedule.
•
Monitors to achieve the set program.
•
Follows the inspection, test plans and submits records to LTMRHL for their reviews and approval through EDMS (such as electronic data management system).
SURVEYOR
•
Reports are sent to Construction Manager.
•
Marks layout for the foundation, Centre line of the foundation, checks the levels at different stages of construction and records them in approved format.
SR.TA/CA
•
Instructions are taken from site engineer than reports are made.
•
Responsible for shifting of materials to the location.
•
Supervise safety and ensure proper way of handling of heavy equipment/ materials.
•
Supervise the reinforcement work and formwork. 12
7.6
7.7
SAFETY ENGINEER:
•
Involves in regular safety pep talks, demonstrations of safe practices in work.
•
Helps in providing requisite safety materials as per requirements.
•
Implement and supervise EHS requirements before commencement and during work.
•
Organize training programs on safety awareness.
•
Coordinates with site administration, first-aid center, doctors and hospitals during emergency.
QUALITY CONTROL ENGINEER:
•
Involves in quality pep talks, periodical demonstrations of best practices in work.
•
Arranges routine testing for concrete, reinforcement, and other construction material as per inspection and test plan.
•
Checks for the use of right material at right place.
13
CHAPTER – VIII QUALITY CONTROL The foundation for a successful Quality Assurance program is the control maintained by the Contractor to assure that all materials submitted for acceptance conform to the contract requirements. To accomplish this it is imperative that the Contractor have a functional Quality Control Plan (QCP) to keep the process in control, quickly determine when the process goes out of control, and respond adequately to bring the process back into control.
8.1
DOCUMENTATION
The test results for quality control are required to be maintained by the Contractor for a period of three years upon completion of the contract. The records, either electronic and/or hard copies, shall be maintained at a readily accessible location for review by INDOT at any time. As a minimum the documentation shall include test results for the aggregate tests, mixture tests, and depth of cover of concrete over reinforcing steel measurements.
8.2
QUALITY CONTROL PLAN:
The Contractor is required to submit a QCP that is contract specific and states how the process control of materials, equipment, and operations shall be maintained. As a minimum, the QCP shall include the following information for each project.
•
The name, telephone number, duties, and employer of all quality control personnel necessary to implement the QCP. The minimum number of quality control personnel shall be a QCP Manager, QCP Site Manager, and Quality Control Technician.
•
The location of the testing facility to be used for the determination of the compressive strength of concrete.
14
•
A list of the testing equipment proposed for process control testing, and the test methods and frequency of calibration and verification of the equipment.
•
The source, transportation, handling, and storage procedures, if applicable, for the materials to be used in the superstructure concrete.
•
The procedure for monitoring the aggregate gradation, water absorption, and Bulk Specific Gravity (SSD) to verify compliance with the properties of the aggregates used at the time of the trial batch demonstration(s).
•
The procedures, location, and type of equipment to be utilized during the trial batch demonstration(s).
•
The techniques and controls of the concrete batching operations. A description of the plant, including the capacity and intended batch size, and the methods and sequence by which the plant produces a batch shall be included. The plant shall have been inspected in accordance with ITM 405. The initial and routine equipment checks, including those performed on scales, water meters, and admixture dispensers, mixing equipment, and agitators, if applicable, shall be included.
•
The location, procedures, and frequency for sampling and testing the concrete mix for slump, air content and unit weight, water/cementitious ratio, and compressive strength.
•
The procedure and frequency for monitoring the depth of concrete over the uppermost bar of the top mat of reinforcing steel.
•
The response to process control tests not within the established requirements.
•
The equipment and methods for delivery of the concrete. The description or plan drawing of the traffic patterns for delivery of the concrete mix to the site of work shall be included.
15
•
The procedures for placement of the concrete to include as a minimum the placing sequence, identification of the placing equipment, and a description of the pumping procedures, if applicable.
•
The methods for finishing, texturing, and curing concrete. The description and identification of the equipment shall be included.
•
The procedure for determining when the forms, false work, and centering may be removed. The minimum frequency samples for determination of removal shall be two cylinders or two beams.
8.3
QCP APPROVAL:
The QCP is required to be submitted to the PE/PS for review at least 15 days prior to commencing concrete operations. The Contractor shall sign and date the QCP at the time it is submitted to the PE/PS. The PE/PS will sign and date the QCP if the contents of the QCP are in compliance with the above-noted requirements. Concrete operations shall not begin before the QCP has been accepted and a successful trial batch demonstration completed. Concrete mix designs and trial batch demonstrations may be submitted for approval prior to the submittal of the QCP.
8.4
QCP AGENDA:
The QCP shall be maintained to reflect the current status of the operations, and revisions are required to be provided in writing prior to initiating the change. The change shall not be implemented until the revision has been accepted; however, traffic patterns for delivery of the concrete mix to the site of work may be adjusted for unanticipated conditions without an addendum to the QCP.
16
CHAPTER – IX
MATERIALS USED IN FOUNDATION
The materials bonded in the foundation are: • Cement • Aggregates • Reinforcement • Admixtures 9.1
CEMENT:
In the most general sense of the word, cement is a binder, a substance that sets and hardens independently, and can bind other materials together. The most important use of cement is the production of mortar and concrete —the bonding of natural or artificial aggregates to form a strong building material that is durable in the face of normal environmental effects. 9.1.1 9.1.1.1
TESTS: DETERMINATION OF FINENESS OF CEMENT BY WET SIEVING CODE OF PRACTISE:-IS 4031(PART15)-1991 APPARATUS:-
Balance of 0.1gm accuracy and 45micron sieve.
PROCEDURE:-
•
Take a representative cement sample to be tested with a sample driver.
•
Take 1000gm of sample.
•
Wet the sample with a gentle stream of water.
•
Remove it from the stream and wash for 1 minute.
•
Return the sieve to the spray of water through a tap and wash it for minute by moving the sieve in circular motion in horizontal plane.
•
Rinse it well and taking care not to lose any of the residues over the sieve. 17
9.1.1.2
•
Blot the bottom surface of sieve with a damp cloth.
•
Dry the sieve and residue in oven or on a hot plane.
•
Cool the sieve brush the residue from the sieve and weigh.
•
Residue percentage=100*residue in gm/wt. of sample before sieving.
DETERMINATION OF CONSISTENCY OF CEMENT PASTE CODE OF PRACTISE:-IS 4031(Part 4)-1993-first reprint. APPARATUS:-
Balance of 0.1gm accuracy, Vicat’s apparatus with plunger, standard weights, graduated glass measuring jar and gauging trowel. PROCEDURE:-
•
Take a representative cement sample to be tested with a sample driver.
•
Take 300gm of cement in evaporation dish and mix water of about 25% by wt. of cement.
•
Care shall be taken that the mixing time is not less than 3minutes or not more than 5minutes from the time of water adding to the dry cement.
•
Place the mould of the vicat’s apparatus on a non-porous plate and fill the mould with the paste.
•
After filling, smoothen the surface of the paste, making it level with the top of the mould.
•
Shake the mould slightly to expel the entrapped air.
•
Place it below plunger of vicat’s apparatus and lower the plunger gently to touch the surface of the test block.
•
Quickly release the plunger, allow it to sink into the paste and record the penetration of plunger from the bottom of the mould.
•
If this is not in between 5-7mm, take a fresh sample of the dry cement of same weight and all little more water and repeat the test.
•
Repeat the above test with increased water content until the penetration of plunger in the cement paste between 5-7mm.
18
•
Therefore, the standard consistency of cement paste is the percentage of water required, where the plunger penetrate into the cement paste of about 5-7mm from the bottom of the mould.
Fig 9.1: Vicat’s Apparatus
9.2
AGGREGATE:Aggregates are inert granular materials such as sand, gravel, or
crushed stone that, along with water and Portland cement, are an essential ingredient in concrete. 9.2.1
TESTS
9.2.1.1
DETERMINATION
OF
PARTICLE
SIZE
DISTRIBUTION
OF
AGGREGATES CODE OF PRACTICE: IS 2836: part 1: 1993(tenth print)
APPARATUS:
Balance of 0.1 gm., accuracy , IS sieves 63mm, 50mm, 40mm, 20mm, 12.5mm, 10mm, 4.75mm, 2.36mm, 1.18mm, 600 micron, 300 micron, 150 micron and 75 micron.
PROCEDURE:
•
Take a representative air dried sample by quartering method or by sample driver.
•
Record its weight before sieving. Sieve the sample successively on sieves for which the size distribution is to be analyzed, starting from the largest. 19
•
Shake each sieve separately on clean tray until 2 minutes.
•
The sieving shall be done forward, backward, circular, clockwise and anti-clockwise with frequent jarring. So that material kept on sieve frequently changes its direction.
•
Material other than 20mm size shall not be forced through.
•
Lumps of fine material present can be broken by gentle pressure by hand
•
Fine camel hair brush may be used to clean the undesirable of IS sieve 150 micron and 75 micron.
•
Weight the material retained on each sieve and records them.
•
Cumulative mass of aggregate fraction shall than be calculated and percentage of minimum weights of sample for sieve analysis.
Table 2:
Sieve analysis specifications
Fig 9.2: Gradation of aggregates
20
Fig 9.3: Sieves
9.2.1.2 DETERMINATION OF AGGREGATE IMPACT VALUE CODE OF PRACTICE: IS 2386(part-4) – 1990 - tenth print APPARATUS:
Impact testing machine with free falling hammer of 13.5 to 14kg with a height of fall of (380 +5mm).,(380-5mm).,with supporting means of hammer whilst fastening or removing cups., cylindrical steel cup of internal diameter 102mm and 50mm deep; IS sieves 12.5mm , 10mm ,.36mm .,cylindrical metal measure of internal diameter 75mm 1nd 50mm deep. Tamping rod of 10mm diameter, 230 mm long with rounded at one end. Balance of 0.1gm., accuracy, thermostatically controlled oven. PROCEDURE:
•
Sample of aggregate passing 14mm sieve and retain on 10 mm sieve was taken.
•
Put into a metal tray and compacted by tamping rod for 3 layers.
•
Measure the weight.
•
Three samples were taken as same procedure.
•
Samples were sieved by 2.36 mm sieve.
•
Sieve three samples for same time period.
•
Weights of retain and passing were measured.
•
Aggregate impact value = weight of load sample/wt. of passed sample 21
Fig: 9.4 AGGREGATE IMPACT TESTING MACHINE
9.3
REINFORCEMENT:
Reinforcement is defined as a system of steel brands, strands, wires or mesh for absorbing the tensile and shearing stresses in the concrete work.
9.3.1
TENSILE TEST CODE OF PRACTICE:ISO 527 STANDARDS: ASTM D 638 and the equivalent APPARATUS: 40 T.U.T.M, calipers, wooden piece. PROCEDURE:
The ductility of a sample is determined and conducting a tensile strength test on a universal testing machine. Samples of the material are placed in a universal testing machine. Gripped by the ends, and a vertical force is applied until they break; they are pulled apart during the stretching process, the machine measures the load (ρ), or the force applied to the sample, and the displacement of the sample(s), along with the original cross sectional area of the sample (A°), and the original length (L₀), an engineering stress- strain curve can be created. Stress (Δ), computed by dividing the load by the cross sectional area, is plotted against strain (є), derived by dividing the displacement(s), by the length: Δ = ρ / A₀ Є = s / L₀
22
When the graph is analyzed, it is found that the strain hardening of the material increases up to a certain maximum point, after which the strain begins to deform the material, softening it until it breaks. Graphically it is the highest point on the engineering stress strain curve. The maximum point is known as the ultimate tensile strength, or universal testing machine, and is used in measuring the ductility of metals.
YOUNG’S MODULUS:
This is the slope of the linear portion of the stress strain curve; it is usually specific to each material, a constant, known value. YIELD STRENGTH:
This is the value of the stress at the yield point which is calculated by plotting young’s modulus at a specified percent of offset (usually offset = 0.2%) ULTIMATE TENSILE STRENGTH:
This is the highest value of the stress on the stress - strain curve. PERCENT ELONGATION:
This is the change in gauge length divided by the original gauge length.
ELASTIC LIMIT:
The elastic limit is the limit beyond which the material will no longer go back to its original shape when the load is removed, or it is the maximum stress that may be developed such that there is no permanent or residual deformation which the load is entirely removed. ELASTIC AND PLASTIC RANGES:
The region in stress - strain diagram o top is called the elastic range. The region from p to R is called the plastic range. YIELD POINT:
Yield point is the point at which the material will have an appreciable elongation or yielding without any increase in load.
23
ULTIMATE STRENGTH:
The maximum ordinate in the stress – strain diagram is the ultimate strength or tensile strength. RUPTURE STRENGTH:
It is the strength of the material and is also known as breaking strength.
9.4
ADMIXTURES :
RHEOFINISH 288 FD: Water based, surface retarder for concrete DESCRIPTION:
RHEOFINISH 288 FD is a medium viscosity, liquid retarder used for achieving an exposed aggregate finish on concrete by retarding the setting of cement paste in the surface matrix of concrete and then removing it. The surface retarder is applied on the formwork or sprayed on the freshly poured concrete surfaces to effect retardation of the cementitious paste in the top surface layer. USES:
RHEOFINISH 288 FD is recommended for all concrete where it is desired to obtain an exposed aggregate finish or a keyed surface for a superior bond with subsequently placed concrete or mortar layer. The variable depth of retardation allows considerable flexibility to architects in using different shapes and sizes of aggregate to produce attractive patterns of exposed aggregates on cast in-situ or precast panels. MECHANISM OF ACTION:
As concrete cures, RHEOFINISH 288 FD temporarily halts the set of the concrete at the surface. Controlled penetration delays the set of the surface only and allows the mass of concrete underneath to harden normally the next day; the retarded surface concrete is brushed or washed away exposing the aggregates.
24
ADVANTAGES
•
Water based – no solvents.
•
Consistent textured finish.
•
No deleterious effect on the core concrete or the strength of the concrete mass.
•
Scope for producing decorative patterns of exposed aggregates with different shapes and size of aggregates.
•
Excellent bond for subsequently laid mortar or concrete layer. Avoids costly surface roughening procedures.
•
No mould release agent needed when used as form retarder.
•
Excellent for intricate, complicated moulds and for vertical forms.
•
Economical – high coverage rate The surface retarder shall be RHEOFINISH 288 FD, water based,
chloride free formulation. The product shall be formulated to perform as surface retarder for formed concrete as well as top surface applications. DIRECTIONS FOR USE
Exposed concrete / flat works
:
SURFACE PREPARATION:
Pour concrete and screed, float or trowel level. For a denser and more uniform face, sprinkle extra aggregates on to surface and work in with trowel or roller, making sure the aggregates are flush with the surface and surrounded by cement paste. Do not overwork the surface with a steel trowel as this tends to seal the top surface, thus restricting the penetration of the RHEOFINISH 288 FD. MIXING:
Use RHEOFINISH 288 FD as supplied after stirring thoroughly. Pouring RHEOFINISH 288 FD back and forth between two pails will help to ensure the product is properly mixed and any material clinging to the side or bottom of the pail has been removed.
25
APPLICATION:
As soon as surface water has disappeared (normally within 30 minutes), spray until the colour of the retarder just hides the area to be exposed or as per the suggestive rate of application for the depth of exposure warranted. Protect areas adjacent to the job from overspray which may stain these areas.
Fig 9.5: Concrete cured using admixture
26
CHAPTER – X CONCRETE MIX
•
Weigh out the designed proportions for a 1.6 cubic foot batch of concrete.
•
Divide the water into two buckets, one with about 3/4 of the water. If using air Entraining, put the air entraining agent in the 3/4 water bucket.
•
Put about half the coarse aggregate, half the fine aggregate and the 3/4 bucket of water with air entraining in the mixer.
•
Start the mixer and mix until the aggregate is thoroughly wet.
•
Carefully add all the cement with the mixer running. Try not to make a lot of dust! Add a little more water and mix until all the cement is blended in.
•
Incrementally add the rest of the coarse and fine aggregate – mix until blended in.
•
In very small increments, add enough water from the final quarter of the water to produce a workable mix. A little water goes a long way!!
•
Mix for three minutes, followed by a three minute rest, followed by a two minute final mixing. Cover the mixer opening with a damp towel while resting.
•
Dump some mix out of the mixer into a pan. Perform a slump test. If results are satisfactory, skip to the next step, otherwise:
•
If the slump is less than required, return the concrete to the mixer, add any remaining water, and mix for one minute.
•
Perform a second slump test. If results are satisfactory, move on.
•
If the slump is still less than required, return the concrete to the mixer, add additional water, as well as additional Portland cement to maintain the desired water/cement ratio (Wt. of PC added = Wt. of water added/WC ratio), and mix for one minute.
•
Continue taking slump tests and adding water and cement until the desired slump is obtained.
•
Record the final slump and the actual weight of water and cement used.
•
If using super plasticizer, add it to the mixer and mix for one minute.
27
Fig 10.1: Concrete mixer
Fig 10.2: Mixing of Concrete
28
Fig 10.3: Concrete placed in moulds
Fig 10.4: Curing of concrete moulds
29
10.1
TESTS TO CHECK QUALITY OF CONCRETE
10.1.
1SLUMP TEST
This is a site test to determine the workability of the ready mixed concrete just before it’s placing to final position inside the formwork, and is always conducted by the supervisor on site. However in mid of concreting process , should the site supervisor visually finds that the green concrete becomes dry or the placement of concrete has been interrupted , a re-test on the remaining concrete should be conducted in particular of the pour for congested reinforcement area . The procedure of test in brief is as follows: PROCEDURE:
i.
The internal surface of the slump cone shall be thoroughly cleaned and should be free from any set concrete before commencing the test. The mould should be placed on smooth horizontal, rigid and non – absorbent surface such as carefully levelled metal plate. The mould is firmly held in position while filling it.
ii.
The mould should be filled in 4 layers each approximately one quarter of the height of mould. Each layer shall be tamped with 25 blows. The stroke should be distributed in a uniform manner over the cross section of mould. For the 2 nd and subsequent layers tamping rod should penetrate into underlying layer. The bottom layer should be tamped throughout its depth.
iii.
After the top layer has been rodded the concrete shall be struck off level with trowel or rod. The mortar, which may have leaked out between mould and base plate, shall be cleaned away.
iv.
The mould shall be removed from concrete immediately by raising it slowly and carefully in vertical direction. This will allow the concrete to subside and the slump shall be measured immediately by determining the difference between height of mould and that of highest point of slumped concrete specimen. The above operation shall be carried out in a place free from shock or vibration. 30
Fig 10.5: Slump cone test
Fig 10.6: Tamping and placing concrete in layers
31
10.1.2 COMPRESSION TEST:
The Compression Test is a laboratory test to determine the characteristic strength of the concrete but the making of test cubes is sometimes carried out by the supervisor on site. This cube test result is very important to the acceptance of in-situ concrete work since it demonstrates the strength of the design mix.
CODE OF PRACTICE :
IS 516-1970-second print
PROCEDURE:
•
Generally, concrete cubes are tested at an age of 7 or 28 days.
•
These are to be tested immediately after removing from water and while they are in wet condition.
•
Wipe off the surface water and remove the fins if any.
•
Check the dimension and note down the weight.
•
Wipe the bearing platens of testing machine cleanly. Place the cubes in such a manner that load shall be applied to opposite sides of cube cast, i.e., not to top and bottom.
•
The faces of test specimen and steel plates of testing machine shall not be packed.
• •
Rotate the movable portion gently by hand, so that uniform seating is obtained. Apply the load without any shock continuously at rate of 140kg/sq.m/min until the resistance of specimen to increase of load breaks down and no greater load can be sustained.
•
Record maximum load applied to specimen Average of three specimens shall be taken as sample of representative batch
provided individual variation is not more than 15% of average. For cores, a correction factor according to ratio of height to diameter shall be applied. After applying correction, equivalent cube strength of concrete shall be determined by multiplying the corrected cylinder strength by 5/4. Compressive strength (kg/sq.m (or) N/sqmm) = (maximum load applied)/cross-sectional area).
32
Fig:10.7 COMPRESSION TESTING MACHINE
Fig:10.8 CONCRETE BLOCKS AFTER TESTING
33
10.2.
BATCHING PLANT:
A batching plant is a manufacturing plant where the ingredients used to produce concrete are mixed before being transported to a construction site ready to be poured. A concrete batching plant is the ideal form of concrete machinery where a reliable supply and exact deployment of concrete is required.
The advantages of concrete batching plant to construction sites are: •
Eliminate the problems of inefficiency.
•
Minimize the risk of waste and therefore of loss of profits (concrete is mixed to exact specifications so no rejection of the final product, there is no over or under supply of concrete, no delivery delays and on site time wastage, no risk of the concrete being too wet or too dry). Concrete batching plants fall into two broad categories. One is a long-term stay or permanent high capacity batching plant, which generally consists of silos, bins, concrete batchers, conveyors and control equipment. The other type of concrete batching plant, which is becoming increasingly popular, is the mobile (portable) batching plant. Mobile batching plants consist of frameworks carrying batchers, conveyors, scales, control equipment; small silos and adapted to be transported from site to site.
34
Fig 10.8: Batching Plant
35
CHAPTER - XI
SEQUENCE OF WORK
a.
Permitting to obtain statutory work.
b.
Training on construction work procedure (CWP).
c.
Preparation of BBS and submission to reinforcement fabrication yard.
d.
Marking for barrication.
e.
Marking and barricading of “foundation” zone.
f.
Fixing of barricades for permanent works as per document.
g.
Removal of existing road median.
h.
Excavation for foundation with working space by maintaining required slope.
i.
Disposal/preservation of excavated soil by confirming soil properties.
j.
Levelling at foundation bottom with PCC.
k.
Marking the co-ordinate of foundation.
l.
Tying of reinforcement.
m.
Shuttering of foundation using approved formwork system.
n.
Pouring of concrete.
o.
Curing.
p.
De-shuttering of formwork.
q.
Backfilling and compaction.
36
CHAPTER – XII
WORK PROCEDURE-OBTAINING STATUTORY WORK PERMITS
a.
The work shall be commenced after obtaining statutory permits from the traffic police department and greater Hyderabad Municipality Corporation and other government bodies.
b.
Requisite permission is taken from the safety department before starting the activity on the site.
12.1
TRAINING ON CONSTRUCTION WORK PROCEDURE
a.
Construction team should be trained.
b.
Awareness through safety pep talks regarding vehicular movement inside working zone and road traffic shall be undertaken.
12.2
MARKING OF FOUNDATION FOR EXCAVATION
a.
Marking of open foundation as per coordinate shall be done as per the GFC drawing at site in the barricading zone by lime powder before starting of excavation.
b.
Corner co-ordinate as furnished by DDC shall be marked on top of PCC as per CWP.
37
12.3
SAFETY BARRICATION:
Fig 12.1 Barricading
12.4
REMOVAL OF MEDIAN:
a.
Median shall be dismantled by the excavator or breaking equipment.
b.
Any projected part for median shall be leveled before excavation for foundation.
c.
Dismantled median material shall be disposed to proper place.
d.
Barrication area shall be such manner to maintain level ground to avoid obstruction for vehicle movement inside the barrier.
38
12.5
EXCAVATIONS :
a.
Excavation for structures should be done by removing material on the planned location as per markings and dimension as shown in the GFC drawing and slope shall be maintained. The sequence of excavation and vehicle positioning shall be done as per the typical excavation plan.
b.
Excavator/ pneumatic equipment shall be used to excavate the earth crust.
c.
Excavation shall be done with (300- 400mm) working space on both side along the width at bottom of foundation.
d.
Slope shall be maintained on either side along the longitudinal direction of the alignment as detailed in annexure F.
e.
Steps with 350 mm tread X 250 mm riser shall be provided to go down inside the excavated pit in the direction of alignment. The steps shall be cut manually.
f.
In case of any hard rock to be excavated, it shall be removed using excavator / jack hammer. Excavator with rock breaking arrangement shall be used. In case it is desired that jack hammer with mole point is used, it shall be pressed down firmly and drilling operation is done by pressing the rock deeply, until the rock is through into the dirt underneath. The jack hammer shall be pressed at an angle to loosen the rock and remains shall be removed with the excavator.
g.
In case of any water ingress, a sump (500x500x300 mm) shall be provided in the opposite side of the step to collect water.
h.
Excavated bottom surface shall be done in 1:250 slopes to drain the ingresses water to the sump.
i.
Dewatering pump shall be provided on sump side for removing water during monsoon period or due to ingress of ground water.
j.
Checklist for excavation shall be followed. 39
Fig 12.2 Excavation for foundation
12.6
DEWATERING:
a.
The water collected in the sump shall be dewatered by using pump.
b.
The water shall be pumped in water tanks placed on the ground.
c.
The water stored in the tanks shall be transported in tankers to nearest casting yard and shall be used for used for dust suppression.
12.7
DISPOSAL:
a.
Foundation pit shall be dry, clean and free from any foreign materials.
b.
Excavated earth/dismantled median shall be disposed from the barricading zone to prior allocated disposal area by tipper and excavated and information shall be passed to LTMRHL accordingly from time to time. Disposal shall be done at the designated areas and a joint inspection of the dumping area along with LTMRHL shall be carried out by RFL. During the inspection all documents related to the land shall be made available. This inspection shall be once per dump area and upon the completion of inspection the RFL shall be closed. In case the excavated earth is being dumped in the area in possession of the contractor, no such information shall be passes on to LTMRHL. 40
c.
No excavated soil shall be kept near the excavated area.
d.
Disposal land shall be well dressed to prevent mixing of local/rejected soil with reusable materials.
12.8
BED PREPARATION]
a.
Excavation shall not be done till PCC bottom, i.e., the excavation shall be done 100 mm above bottom level of PCC by mechanical excavator. Remaining depth till the PCC bottom shall be excavated manually.
b.
Surface shall be compacted and levelled manually by sprinkling water and making the area free from any loose particles.
c.
Care shall be taken to avoid water logging on compacted and levelled surface.
d.
Temporary barricading shall be provided to close the access around the excavated pit.
e.
Narrow path shall be made along the periphery of excavated surface to collect water into the sump until the foundation concrete works are completed.
Fig 12.3 Levelling of bed
41
12.9
CHECK FOR BEARING CAPACITY OF SOIL:
a.
At all foundation locations the confirmatory bores have been conducted and N value is being established at various levels. Based on the confirmatory bores the founding level has been derived by the designer and incorporated in the drawings.
b.
After the excavation has been done to the required depth as indicated in the drawing, the geologist will inspect the foundation and will co-relate with the data observed during the confirmatory bores with the actual strata observed at site and shall confirm the foundation level.
c.
The geologist then allows site to proceed with PCC or CLSM through a checklist prepared by him.
12.9.1 PCC/CLSM:
Referring to the drawings of GHCs of “Schedule of piers” if the difference between founding level and excavation level then CLSM is to be filled, then in this case no PCC is done. The rebar placing should be kept over the finished level of CLSM. When the founding level and excavation level is same, then PCC is laid for about 100mm thick. 12.9.1.1 PCC
i.
Once the excavation level is completed according to the drawings then through Auto level the level is to be checked. Coordinates of PCC shall be marked using iron pegs at the corners.
ii.
PCC level is marked with paint by giving levels using Auto level instrument. The surface should be compacted manually and moisten with water. Timber or steel channel shall be fixed on all four sides to maintain uniform thickness. PCC of grade M15 then shall be placed up to the required level and shall be compacted.
42
iii.
Pouring of concrete shall be done either by hose attached to concrete delivery pumps or by portable G.I chute directly from the transit mixer, depending on the ground situation.
iv.
The slope for chute shall be so adjusted that the concrete flows freely and the height of fall is less than 2m to avoid segregation of ingredients.
12.9.1.2 CLSM
i.
All the ingredients of CLSM designed are a part of concrete ingredients; hence CLSM should be produced in the approved concrete batching plant with the same procedure that of concrete have to be transported to site as per CWP.
ii.
Inspection and testing o CLSM should per as per CWP.
iii.
Slump with a range 200+50mm or 200-50mm of CLSM should be maintained during placing and also temperature is also checked.
iv.
Temperature of CLSM should not be more than 30’C during placing.
v.
The mixture should be discharged within 2.5 hours after water is added. The CLSM mixture shall be placed directly into the trench or excavation. The mixture flow should be such that no labor shall be required in trench or excavation. No vibration or compaction equipment should be used. The excavated pit should be moistened by sprinkling water prior to filling of CLSM.
vi.
CLSM shall be placed by chutes or pumps depending upon its accessibility. The maximum height of free fall for CLSM from chute shall not be more than 2m.the top surface of CLSM shall be cured by wet hessian cloth for about 24hrs, after which reinforcement should be placed.
43
Fig 12.4 Curing the PCC Bed
12.10 MARKING FOR FOUNDATION:
a.
Marking of foundation for tying reinforcement, shuttering shall be done as per coordinates given in GFC drawings.
b.
4 corner coordinates as per furnished by DDC shall be marked on the top of PCC as per CWP.
c.
Outlines of the foundation Centre of pedestal and pier location on PCC shall be drawn using red oxide powder and cotton thread, before laying the reinforcement.
d.
The same coordinates marking shall be provided on the ground after completion of the activity.
44
Fig 12.4 Marking foundation using total station
12.11 REINFORCEMENT:
a.
TMT Fe500 steel bars of approved vendor should be used.
b.
Reinforcement steel should be supplied to steel bending yard directly from manufacturer.
c.
Reinforcement shall be stacked on sleepers or concrete blocks to avoid direct contact with local earth. The sleepers or concrete blocks shall be of 200 mm height and placed at a c/ c distance of 3m.
d.
Reinforcement shall be marked batch wise and tested as per inspection and test plan.
e.
Reinforcement which confirms to the requirements shall be used for cutting and bending.
f.
BBS shall be used for cutting and bending.
g.
Reinforcement shall be protected from rusting, mortars, mills scale, grease oil or paints by covering with tarpaulin sheets as per the requirement in site.
h.
Handling of reinforcement shall be in such a way so as to prevent damage or unwanted bending. 45
Fig 12.5 Cover blocks Fig 12.6 cover block moulds
12.11.1CUTTING AND BENDING OF REINFORCEMENT
a.
Reinforcement steel shall conform to the dimensions and shapes given in the approved bar bending schedules.
b.
Reinforcement steel shall be fabricated through automatically operated machines and mandrels confirming to IS1786:2008.
c.
Cut and bent reinforcement shall be stacked on sleepers and protected to prevent rusting by covering with tarpaulin sheets.
d.
The acceptable tolerances for placing the reinforcement are: i.
Overall depth – less than/greater than 10 mm for depth ≤ 200mm and less than/greater than 15mm for depth greater than 200mm.
ii.
Cover to the reinforcement – least of 1)one third of specified cover 2)5mm
iii.
Center to center distance – around 10mm.
12.11.2TRANSPORTATION OF REINFORCEMENT:
a.
Cut and bent reinforcement shall be transported to place of work on trucks or trailers.
b.
Unloading of reinforcement at site shall be done either manually or by crane and checking the material test certificates for the particular lot.
c.
Reinforcement shall be stacked on elevated blocks in clean and dry conditions.
46
12.11.3PLACING OF REINFORCEMENT:
a.
Reinforcement shall be tied together at every intersection with GI Binding wire (Min 19 gauge).
b.
Lap length shall be as given in the GFC drawing and shall be staggered.
c.
Couplers may be also be used. Wherever used, couplers shall be staggered at least by the distance of lap length shown in drawing.
d.
Only cover block made of grout or concrete shall be placed at suitable locations to maintain clear cover.
e.
Space bar shall be provided at 2m intervals in between reinforcement layers as equal to maximum diameter of steel.
f.
Placing and fixing of reinforcement shall be inspected by the construction engineer.
g.
Reinforcement chair shall be provided at 1mm c/c to maintain the spacing and sagging between bottom and top reinforcement.
h.
Projecting reinforcement shall be coated with inhibitor solution and cement slurry for protection against rusting. Inhibitor solution is a clear liquid of pH value of 12-14 and specific gravity of 1.04 minimum this inhibitor solution shall be stored in closed plastic container.
i.
Before starting the treatment arrangement such as tools and tackles such as buckets, brushes, weighing balance etc. shall be provided.
j.
Slurry of an inhibitor solution and cement (OPC) at a ratio of 0.5-0.6:1 shall be prepared and mixed thoroughly till the mix attains consistency.
47
k.
The reinforcement shall be applied to the bars to cover the entire surface of the projected area.
l.
The coated steel bars are allowed to dry at least 6-12 hours or till it is touch dry. m. Apply second coat of application. The thickness of the coating after this shall be 200-300 microns.
n.
This coated reinforcement shall be used within 15 days from the date of application of second coat.
o.
Vertical ledger pipe shall be provide inside the foundation through 75 dia PVC pipe embedded into the concrete at required locations for scaffolding for enabling works and support for keeping the reinforcement in position. The verticality of the pipes shall be maintained by supporting it with additional reinforcement.
p.
After completion of the work, the void created by placing PVC pipe shall be grouted with non-shrink cementitious grout mix. It shall be poured into vertical openings provided for temporary staging. It shall be done before road restoration and source approval shall be taken prior to its usage. The non-shrink cementitious shall be mixed with clean single sized 10mm aggregate at 1:1 ratio at a water powder ratio of 0.16-0,18. Before filling of the grout mix, the PVC pipe shall be broken at least to 50mm inside the foundation from top and the grout mix shall be compacted in layers of 150mm and roded by 16mm diameter rod with bullet end.
q.
Survey checking shall be done after completion of reinforcement. The survey records with the sketch shall be attached with ’check list for concrete.
48
Fig 12.7: Placing and tying of reinforcement
12.12 SHUTTERING:
a.
Marking for shuttering work shall be given by surveyor as per coordinates given in GFC drawings.
b.
The marked coordinated marking shall be checked after fixing of the shutter
c.
Prefabricated steel formwork shall be used.
d.
Shutter shall be dry and free from foreign materials before applying approved release agent.
e.
Surface shall be coated with mould releasing agent using brush to prevent adhesion of concrete to the formwork before fixing of shutters. It shall be applied as per the manufacture’s specifications attached in annexure F care shall be taken that the material so applied does not leave any blisters, voids, blow holes and detoriation of application. Concrete shall be poured within 7 days after application of releasing agent.
f.
Support to shutter shall be provided as per approved shuttering scheme.
g.
All fixtures like nut and bolts for steel formwork shall be countersunk and well ground to provide smooth form finish.
49
h.
Forms shall be made sufficiently rigid by the use of ties and bracing to prevent any is placement between supports.
i.
Shifting and placing of shutters shall be done manually or with the help of a crane.
j.
Starter for pedestal shall be fixed with foundation shutter and same for pier shall be continued during pedestal operations.
k.
Cover blocks shall be provided in between surface of formwork and reinforcement.
l.
Support to the shutter shall be as per the shuttering scheme for the said formwork.
m.
All bolts and fixtures shall be tightened to make the shutter a single unit.
n.
Provision shall be made for safe access on, to and about the formwork.
o.
Survey checking shall be done after completion of formwork to measures the center point as well as every corner of foundation.
p.
The shuttering shall be monitored for any kind of displacement and settlement during pouring of concrete.
50
Fig 12.8 Form work for foundation
12.13 CONCRETING :
a.
Concreting shall start within 24 hours after checking and others statutory permission otherwise the permissions have to be taken again.
b.
The foundation area for concreting shall be free from dirt and water.
c.
The M35 grade concrete shall be used. Temperature shall be checked for every transit mixer before unloading.
d.
Concreting shall be done in layers and at no time the thickness of layer shall be more than 00mm.
e.
Construction joints shall be avoided and if necessitated provision shall be made for interlocking with the succeeding layer. It shall be prepared by cleaning by an air-water jet and wire brushing on the concrete which is still soft enough that laitance can be removed, but hard enough to prevent aggregate from loosening. Concrete that has set shall be prepared using a wet sand blast or ultra-high pressure water jet. 51
f.
The concrete mix is designed keeping in view the hot weather of Hyderabad. It is further detailed in CWP for concrete production and transportation. The temperature of concrete shall not exceed 30 degree centigrade.
g.
In hot weather adequate manpower shall be available to quickly place, finish and cure the concrete. Forms and reinforcement shall be dampening prior to placing of concrete but care shall be taken to avoid excessive spending of water. Finishing shall be started as soon as the water sheen has left the surface and curing shall be started as soon as the finishing is over.
h.
All construction joints and expansion joints shall be exposed for its full length with clean and true edges.
i.
Pouring of concrete shall be done either by hose attached to concrete delivery pumps or by portable G.I chute directly from the transit mixer, depending on the ground situation.
j.
The slope for chute shall be so adjusted that the concrete flows freely and height of fall is less than 1.5 M to avoid segregation of ingredients.
12.14 COMPACTION OF CONCRETE :
a.
Concrete shall be thoroughly compacted by using frequency and needle vibrators (40 mm and 60 mm dia.).
b.
Before using a vibrator, check shall be done for its proper operations. The vibrator shall be placed in the higher levels of the concrete first and when a fairly even surface is obtained, it shall be inserted at regular intervals for consolidation. Vibration shall be done with the head totally submerged in the concrete maintaining consistency of spacing and vibrating time. The vibrator shall be stationary for 5 to 15 seconds depending upon the mix and force of vibrator. Less time shall not allow proper consolidation or entrapped air to escape to much can cause segregation. The vibrator shall be put out slowly from the concrete so that concrete can be filled behind. While placing the next lift 52
insert the vibrator at least 100 mm into the previous lift to stich the layers together and eliminate
cold joints. Vibrators shall not be used to separate
concrete. c.
Adequate care shall be to ensure that the vibrator needle does not touch the shutter, reinforcement and other insert ducts etc.
12.15 FINISHING OF CONCRETE:
a.
Concrete top surface shall be smoothed with a float.
b.
The top face of a foundation intended to be surfaced with other material shall be left with a spaded finish.
c.
Concrete shall be placed at the lowest point and proceed toward the highest point.
d.
For finishing of concrete on the slope portion, marking shall be done on the side shutter. To maintain the level on the sloped portion a line dori shall be tied from the marking portion on the side shutter to the bottom of the pedestal shutter. The concrete shall be finished using a float.
12.16 CONSTRUCTION JOINT PREPARATION:
a.
Wherever construction joint is required on the surface of the fresh finished concrete, surface retarder shall be sprayed as soon as the sheen of water disappears. The rate of application shall be 100-129 ml per sq.m. The retardation depth is up to 8 mm. The sprayed shall be left as it is till the final setting of concrete.
b.
Construction joint shall be prepared by cleaning by an air water jet or wire brooming on the concrete which is still soft enough that laitance can be removed, but hard enough to prevent aggregate from loosening. If the concrete for some reason is set before the construction joint preparation, then in such situation the joint shall be prepared using a wet blast or ultra-high pressure water jet. 53
12.17 CURING:
a.
Curing of concrete shall start immediately after the concrete has attained the final setting
time. It shall be carried out by spreading hessian cloth and
sprinkling water at regular intervals. b.
Wet curing shall be done for 15 days.
c.
Curing compound shall be used after taking necessary approvals and the details of the same shall be submitted separately.
Fig 12.9 Curing of foundation using
12.18 DE-SHUTTERING:
a.
Formworks shall be removed after 24 hrs. From time of pouring.
b.
Formwork shall be removed without jarring the concrete.
c.
Crane or any other suitable equipment shall be used to remove the formwork.
d.
Formwork components shall be stacked properly after removing by ensuring good housekeeping practices.
54
12.19 BACKFILLING AND COMPACTION:
a.
Approved soil or crusher dust shall be used as backfilling material up to bottom of sub-grade layer.
b.
The soil or crusher dust shall be from approved source.
c.
The earth shall be compacted in layers of 200 mm with the help of impact rammers or jump compactors to achieve 95% of the maximum reached in trials.
d.
The crusher dust shall be compacted in layers of 500 mm and hydraulically compacted. For hydraulic compaction the crusher shall be spread uniformly to 500mm thick flooded with water and left for 04 hours before laying next layer.
e.
The thickness shall be controlled by providing layer thickness markings on the surface of concrete.
Fig 12.10 Backfilling of foundation
55
56
CHAPTER – XIV
MANDATORY SAFETY REQUIREMENTS
a.
Every workman must be engaged after screening, safety induction & medical test.
b.
Every workman shall be allowed to work with personal protective equipment (safety shoes, safety helmet, reflective jackets, hand gloves, nose musk, ear plug, safety goggles).
c.
Area of work shall be barricaded with boards with proper anchoring, bolting and weigh to be kept for stability of barricades.
d.
While planning excavation of test pit, it is important to plan against the following:
--
collapse of the sides, material falling on the people working in the zone, people and vehicles falling into excavation, people being stuck by plant and machinery, access to the work area, fumes, toxic gas underground utilities. Accidents to members of the public.
e.
Certified crane & vehicle shall only be deployed for the job
f.
Operator with license shall be permitted to operate the crane.
g.
Proper access and working platform shall be provided to reach the work spot.
h.
Safety warning signs shall be places to provide adequate warning.
i.
Where natural lighting is not adequate, working light fittings or portable handlamps shall be provided at workplace.
57
