This civil works method statement details general procedures for concrete works at any kind of project. This method statement for concrete works applies to all concrete work of permanent structure except lean concrete to be used as a structural fill and backfill. The normal sequence of concrete works is:
- Curing
- Bituminous Protective Painting
- Back Filling
- Block Work
- Finishes
Project Manager has the overall responsibility for the implementation of this method statement and shall well ensure that the approved Supplier for Ready Mix Concrete/Independent Testing Agency and Sub-Contractors as well other team members are aware of the requirements of the method statement.
Project Manager is responsible to coordinate with the company PRO and the local bodies for obtaining necessary and essential work permits – if any, for proceeding with the works.
Construction Manager/ Project Engineer will ensure that the Resources are available to carry out the works as scheduled.
Project Engineer/Site Engineer is responsible to carry out the works as per approved Shop Drawings, Method Statements.
Site Engineer/Supervisor is responsible to ensure that the work has been carried out as per specifications & drawings and inspections are done as per contract.
Surveyor/Site Engineer/Supervisor is responsible for Setting out the area and measuring, monitoring and controlling the lines and levels.
QA/QC Engineer/ QC inspector is responsible to ensure that the work performed is in compliance with the approved method statement & other applicable requirements.
Safety Officer is responsible to ensure that all safety precautions are in place and that the personnel on site possess the necessary and essential PPE. He is also responsible to ensure that essential work permits are available prior to the commencement of the concrete and any other construction works.
Quality Requirements
The works shall be performed as mentioned in this procedure and the quality assurance requirements shall be consistent with the relevant sections of Quality System Procedure Manual of the contractor as well with the Project Quality Plan.
Quality Control and Tests for concrete shall be as per contract specification.
Testing laboratory shall be approved by the consulting engineer.
Material Requirements
The materials and material manufacturer (Ready Mix Concrete Supplier) covered by this procedure shall be approved by Engineer prior to the commencement of concreting works in the project
Composition of concrete shall comply with that specified in the approved Mix Design. Batching, mixing and delivering of concrete shall be performed in accordance with the trial mix approved by the Engineer for the supply of Ready Mix Concrete.
Site Engineer/Supervisor has the responsibility of maintaining communication between the point of placement, the concrete batch plant and with the approved Concrete Testing Laboratory.
Cement for the concrete works shall conform to the specifications for materials.
Aggregate grading shall conform to applicable specifications. Testing shall be carried out as per relevant requirements of project specifications.
Water shall conform to specification and source of construction water to be approved by the consultant.
Concrete admixture for use in concrete shall be approved by the engineer and shall be as per the requirements of project specifications.
Method Statement for Concrete Works
Formwork
Form works shall be designed and constructed in accordance with applicable codes within the specified tolerances to the shape, lines, and dimension required by the design drawings(s).
Forms shall be coated with approved mould oil or release agent.
Form exposed corners to produce smooth, square, solid unbroken lines. Provide chamfers (20mm x 20mm) for surfaces where indicated on drawings.
For slab work, Shore/ support shall be provided for floor directly under slab being placed so that loads from construction above will safely transfer directly to these shores.
Formwork shall be struck without damaging, disturbing, or overloading the structure. The minimum periods for striking formwork shall be as agreed with Engineer based on the compressive strength results on test cubes. Calculations for formwork shall be submitted for consultant approval.
Reinforcing Steel Works
Steel reinforcement bars to be used on site shall be from approved source only.
Cut and bend steel supplier shall be approved by the Engineer.
Re-bar work shall be performed in accordance with the relevant specifications, drawings and as per the bar bending schedule.
Binding of rebar shall be done using annealed wire of 1.6mm dia. (16 gauge)
The concrete cover to the reinforcement shall be as per approved drawings.
Covers blocks shall be of concrete and of class same as that of the structure.
Fabric reinforcement shall be of approved type complying with BS 4483.
Welded wire fabric shall be lapped for a minimum length of 300mm including one full mesh for deformed wire fabric and two full meshes with 50mm overlap for plain wire fabric .Offset end laps in adjacent widths to prevent continuous laps.
The lap length of rebar shall be as per drawings/specifications.
Rebar and fabric reinforcement shall be stored under cover on timber or concrete blocks at a minimum height of 300mm above ground.
Reinforcement shall be securely fixed in position within a dimensional tolerance of 20mm in any direction parallel to a concrete face and within a tolerance of 5mm at right angles to a face, provided that cover is not thereby decreased below the minimum specified or otherwise as shown on drawings.
Copy of mill certificate of the consignment shall be attached to material delivery inspection report and submitted to engineer for approval upon receipt of rebar at site.
Embedded Items
Anchor bolts, Pipe sleeves, Conduits for electrical works, drains, curb and trench angles, and other inserts as shown on the design drawings shall be placed, secured, and protected during placement of concrete.
Engineers of relevant discipline from the Sub-contractor side shall check installation of embedment.
Construction Joints
Construction joints shall be located as shown on the design drawings. If not shown on the design drawings, construction joints shall be prepared in accordance with the design document requirements. Construction joint schedule shall be approved prior to start of work.
Vertical Joints shall be formed by means of rigid, grout- tight side forms or stop ends designed to accommodate projecting reinforcement & horizontal joints shall be level.
The surfaces of the joints shall be thoroughly roughened, cleaned of all loose and foreign matter and laitance, washed & saturated with water.
Before concreting, joints shall be treated with cement grout or sand and cement grout mixed in the same proportions as that in concrete. Bonding agent (if instructed by the engineer) shall be applied as per manufacturer recommendations.
The placing of concrete shall be carried out continuously from joint to joint. The face edges of all joints, which are exposed to view, shall be carefully finished true to line and elevation.
Approved water stops shall be provided in construction joints in concrete designed to contain liquids and where indicated on the drawings.
Isolation joints in slabs on grade at all points of contact between slabs on grade and interior column pedestals and grade beams and elsewhere as indicated.
Control joints shall be formed in fresh concrete by either saw cutting or by forming. Depth of joint shall be ¼ slab thickness, unless indicated on drawings.
Sliding joints shall be provided, where indicated on drawings, with a preformed slip membrane to ensure positive separation of concrete surfaces.
Preparation for Concrete Placement
Areas to be placed with concrete shall be maintained in clean condition, free from trash, debris, sand and other foreign matters.
In hot weather conditions, area to be placed with concrete shall be suitably covered and protected by tarpaulin sheet placed 20cm above the reinforcement. Water shall be sprayed on forms, reinforcement and base prior to pouring the concrete.
Prior to placing, following items shall be checked by respective site supervisor:
Survey check review: deviation of line, grade, plumb and location of embedment.
Final clean up.
Joint preparation.
Dampness of surface to receive concrete
Contractor site engineer shall initiate concrete pour record & Inspection Request.
Concrete Requisition
After visual inspection by Engineer and approval of IR, Project Engineer/Site Engineer shall initiate requisition to the Ready mix Concrete Supplier.
Concrete Placement Steps
Field Checks
Upon arrival of transit mix truck at site the delivery note will be checked for the actual details like time of batching, quantity, mix type, approved mix design, variation in weighing of materials, water cement ratio & slump checked regularly to the satisfaction of the Engineer.
Concrete Temperature shall be measured using Thermometer and the maximum allowable temperature of concrete shall be 32 degree centigrade.
One set of six (6) cubes for each 75 cum. Or fraction thereof of each concrete class placed in any one day or for each 450 sq.mtr of surface area placed.
One specimen shall be tested at 7 days and 4 specimens shall be tested at 28 days. One specimen shall be retained in reserve for later testing, if required. Two specimens tested at 28 days shall be field cured. All others shall be laboratory cured.
Slump test shall be carried out for each concrete load at point of discharge and one for each set of compressive strength test specimen.
Air content test as per BS 1881 part 106, pressure method; shall be carried out one test for each set of compressive strength test specimen.
Durability test for concrete shall be done as required in specifications as and when directed by the engineer.
Placing of Concrete
No concrete shall be placed during sand storm or rain.
No water shall be added to the mixer truck after batching.
Site Engineer shall take immediate steps to notify the Engineer when a cold joint is imminent and shall assure that the required method of correcting it is adopted as detailed on the drawings.
Pump car, bucket and chute will be used as placing equipment as appropriate.
Chutes shall be used for drop of concrete greater than 1.0mtr in case of thin walls and 2 meter in other work. In case of slab work it shall be 250-500mm.
The slope of chutes should be constant and steep enough to permit concrete to flow continuously down the chute without segregation(1:2 or 2.5 slope)
Concrete shall be deposited in horizontal layers to a compacted depth not exceeding 450mm and in a manner to avoid inclined construction joints.
Procedure for compaction of concrete
Concrete shall be consolidated by mechanical vibrators. The vibrators shall be adequate in number of units and power of each unit to properly consolidate all concrete.
In consolidating each layer of concrete, the vibrator shall be operated in a near vertical position, and the vibrating head shall be allowed to penetrate under the action of its own weights. Vibrator shall be allowed to remain inside the concrete for sufficient time to obtain proper consolidation of concrete.
The vibrator should penetrate rapidly to the bottom of the layer and at least 4 inch into the preceding layer.
Vibrators shall not be used to move or spread concrete.
Concrete shall be placed as soon as practicable after mixing and while sufficiently plastic for full compaction.
Concreting during hot weather (Temperature greater than 40 deg. Centigrade) shall be avoided as much as possible to prevent the occurrence of severe thermal effects.
After concrete placing, site engineer/supervisor shall record relevant details on the format ‘Concrete Pour Record’ in presence of Engineer.
Finishes
Concrete finishes shall be as required in specification and shall be free from voids, honey combing or any other concrete defects.
All concrete shall be power floated to produce smooth even finish unless otherwise specified. Hand trowelling shall be carried out to surfaces of footings, beams etc.
Concrete Curing
During and after placement, concrete and the exposed surface of fresh concrete shall be protected from wind, high temperature and rain.
Curing shall start as soon as free water has disappeared from the concrete surface after placing and finishing.
Concrete surface shall be initially covered by only polythene sheet. Then after required hardening, place the wet hessian cloth and cover with polythene sheet.
Concrete shall be cured for a minimum of 7 days. Curing compound, if used, shall be approved by the Engineer.
Concrete Repair
Repair method of defective concrete shall be determined or selected by Consulting Engineer or in accordance with the disposition of issued Non Conformance Report.
Repair shall not be carried out without written instruction/ approval of Engineer.
Materials
| 1. Formwork material (ply board, soft wood, nails, Tie Rods, Clamps) |
| 2. Mould Release Oil |
| 3. Rebar / Spacers /Binding Wire |
| 4. Polythene Sheet / Hessian Cloth |
| 5. Concrete as per specifications |
| 6. Concrete Repair materials |
Plant & Equipment
| 1. Transit Mixers | 2. Slump Cone, Air Meter |
| 3. Concrete Pump | 4. Thermometer |
| 5. Water Tanks | 6. Measuring Jar |
| 7. Air Compressor | 8. Crane & Skip |
| 9. Mechanical Vibrator | 10. Theodolite/Total station |
| 11. Masonry tools (trowels & hand tools) | 12. Dumpy Level |
| 13. Wheel Barrows | 14. Water Level |
| 15. Cube Moulds | 16. Spirit Level, Right Angle, Plumb Bob |
| 17. Tamping Rod | 18. Hammer |
Health, Safety and Environmental (HSE) Requirements
The entire works will be carried out as per the guidelines established in the Project Specific HSE Plan.
Utmost importance shall be given to safety of personnel and protection of existing above /underground services. It will be ensured that the personnel involved are thoroughly aware of the “Name of the contracting company”/ Employer Safety regulations. To achieve the above the following shall also be ensured:
Tool Box Meetings will be conducted before starting the works.
All personnel will be provided with suitable Personal Protective Equipment.
Required permits will be obtained from the Engineer/ authorities concerned before starting the works.
Plant & Equipment’s shall be fully tested & certified by an independent testing agency. Copies of certificates shall be submitted to Engineer
All pneumatic / lifting equipment’s including booms, slings; chain blocks etc. shall be fully tested & certified by an independent testing agency. Copies of certificates should be available.
The following checks will be done as required:
Rigidity of connections in case of booms of the pneumatic pumps
Check if the grease applied to the wearing parts is adequate.
Check against slippage/breakage of the concrete pumps boom from the sleeves/connections while working.
Check whether the end of the hose has become loose or has slipped from connecting clamps
Check for loose strands of wear, deformation, corrosion and Breakage of parts of the pump.
Check all forms, shuttering’s and bracings are adequate to support the concrete loads and as per the approved design.