REINFORCED CONCRETE

1. OBJECTIVE:

The objective of this method statement is to carry out the RCC works by meeting the technical specification and complying with Standards.

2. SCOPE:

The scope of this method statement includes at all areas at CTSIL, CTSIL site while executing it in accordance with Technical specifications.

4. TOOLSAND TACKLES

· Trowels,

· Shovels,

· Line Dori,

· Gum boots,

· Vibrator,

· Aluminium straight edge,

· Total station,

· Sprit levels,

· Measuring tape,

· Mason finishing trowels,

· Hammer,

· Mason brushes and buckets

5. MATERIAL USED:

· Grade of Concrete shall be based on the design requirement

· Steel from Approved vendor

a) GENERAL:

· Ensure Material approval prior to start work

· Ensure proper surface preparation.

· Ensure Floor protection.

· Ensure necessary safety precautions are in place prior to start.

b) SEQUENCE OF WORK:

Minimum cementitious content per cum of concrete is as per Design Mix.

· Concrete should be placed in position and compacted.

· Concrete by vision should be homogeneous in colour, well graded and it should form a shape of ball when rounded in the hands.

· Locations where concrete is placed are to be free from debris and free from water.

· Foundations to be concreted in layers of thickness as per specification.

· Slabs to be cast in strips and not in alternate bays

· Starter should be of same grade as main member and should be vibrated / rammed into place. Starters are cast after casting of foundation/slab.

· Construction joint locations should be approved or as shown in drawings.

c) READY MIX CONCRETE

· Preference for ready-mix concrete adequate capacity supported by adequate number of transit mixers.

· Check the empty transit mixer for present concrete in the drum. If there is set concrete in the drum, it affects the quantum of concrete received.

· Concrete should be received with a delivery challan and data cycle sheet showing grade and quantity.

· Do not recharge the concrete by adding additive, water, cement

· Slump recommended for RMC as per trial mix

· The first horizontal section of pipe should be at least 7m before the vertical bend is put.

· The vibrations due to pumping should not affect or displace shuttering works.

· Pump rich slurry (one bag) before pumping concrete to lubricate the inner surface of the pipes.

· In case of irregular supply keep the current transit mixer unloading in progress until the next mixer arrive at the site. This avoids the chocking of pipe line due to non-pumping for long duration.

· Be excessively careful while passing the ball while clearing the concrete in the pipe line after the day’s work is over. Due to negligence somebody could get hurt.

· Employ professional hands for connecting pipeline. They will do a neater and faster job without any safety problems.

· Leave the pipeline, under the pump and adjacent areas clean of concrete dumping after the work is completed.

d) SAMPLING AND TESTING OF CONCRETE

· Concrete Sampling frequency shall be 1 Sample for every 50 cum supplied as per the frequency specified in IS 4926:2003,

o Slump Checks shall be done on as need basis with a combination of Visual and physical checks wherever necessary.

o 1 Set of cube specimens shall be cast every 50 cum of concrete supplied.

· Sampling of concrete shall be done at the site and the cubes shall be marked properly for traceability.

· The cubes shall be tested in L&W internal Lab and or the RMC supplier’s laboratory whenever required

e) PLACING AND COMPACTION

· All works should be true to level, plumb and square and all corners and edges in all cases should be unbroken & neat.

· All concrete should be transported with the help of transit mixers to the place of laying as rapidly as possible. When a truck mixer of agitator is used for transporting concrete, the concrete should be delivered to the site of work and discharge should be complete as per trial mix

· Placing of concrete should generally be done using pumps to achieve necessary heights wherever required

· Do not use chutes longer than 4.5m using plain G.I sheet to pour concrete.

· Place cement concrete to the required depth and vibrate it until entrapped air inside concrete is released.

· Pour concrete first into beams and then over the slab portion.

· Concrete should be thoroughly compacted and fully worked around the reinforcement, around embedded fixtures and into corners of the formwork. Vibrate are so applied that centre of mass is being compacted at the time of placing of concrete.

· If the joint is more than a month old use bonding agents as per specification of the manufacturer.

· If the beam is more than 500 mm deep, concrete it in layers.

· Check Column plumb and, beams, slab level during concreting with line dori method or the levelling instrument.

· Use appropriate needles for vibration depending on the aggregate size, reinforcement spacing and element to concrete. For big footings use 60mm needle, for slab use 40mm needle. Ensure that just adequate vibration is only done. Over vibration will lead to segregation of concrete.

· Use wooden runner or Aluminium straight edge to ram so as to form slurry on top of concrete surface.

· Clean the shuttering works of all spilled concrete immediately after concreting.

· Leave vertical construction joints after consultation with the structural engineer.

· Have adequate vibrators, masons required for the rate of concreting planned.

· All surfaces of shuttering shall be moistened before placing of concrete to reduce water loss due to absorption.

· All concrete surfaces should be sprayed with water based curing compound.

f) COLUMNS, WALLS AND STARTER

· In case of deep trenches/footings, it may be done with help of chutes (PVC pipe/GI sheets etc.) or directly from transit mixers from the reasonable height. In columns it can be placed manually with the help of staging. Concrete from wheel barrows should not be dumped away from the face of concrete already been placed. It should be dumped into the face of concrete already in place.

· Remove the shuttering the next day and spraying the water based curing compound over the column to reduce the heat of hydration.

· The columns and walls should be cured.

g) INSPECTION METHODOLOGY

Before concreting

· Ensure that there will be no leakage of slurry at shuttering joints and junctions.

· Ensure all reinforcements are in place especially chairs.

· Ensure the cover blocks damaged during reinforcement laying are replaced.

During concreting

· Ensure proper grade of concrete as recommended by the consultant is employed.

· The concrete should be placed and compacted before initial setting of concrete commences and should not be subsequently disturbed.

· Methods of placing should be such as to avoid segregation. Care should be taken to avoid displacement of reinforcement or movement of formwork.

· Check slab and beam for parallelism using sprit levels before and after concreting.

· Check the top surface of fresh concrete for evenness.

· Ensure sufficient compaction using correct needle size of vibrator.

· Formwork should be continuously watched during and after the concreting. In case of leakages, bulging or sagging immediate action should be taken before Initial setting of the concrete.

After concreting

· Curing carried out as per guideline.

· Columns are curing by water based curing compound.

· Slabs – water based curing compound is used for curing.

· If honey combing seen after de-shuttering, immediate touch up without delay

· Ensure the cube test results are available at the end of the term indicated.

Personnel

· Ensure all personnel loading concrete are wearing gumboots and rubber gloves.

· Ensure personnel are wearing safety Harness during concreting at heights or on periphery of structures.

7. RESPONSIBILITIES.

· Construction Manager: He shall be responsible for overall management of construction activities.

· Site Engineer: He shall be responsible for Executing in safe work method as per drawings and guide the supervisors and work men.

· Site Supervisor: He shall be responsible managing all plant and machineries and labour and safety of the workers

· QA/QC In charge: He shall be responsible for ensuring the quality of work as per the specifications and standards.

· HSE Manager/Engineer: He shall be responsible for assisting to engineer/supervisor to ensure the safety of workers during the progress of work. Safety inductions of each staff and workers shall be done and daily PPE check to be done and tool box talk shall be carried out before the start of work. General safety awareness as well as particular safety precautions and guidelines for activity to be carried out in that particular day shall be discussed.

· Stores officer: He shall be responsible for storing of all materials. Also responsible for maintaining the record of incoming and outgoing and up to date stock details of materials.

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