This procedure covers checks and quality control requirements for carrying out in-situ concrete operations.
Daily concrete requirements shall be provided to the RMC supplier including quantity, mix details, workability time, delivery rate and access arrangements.
Site Engineer shall ensure that checks on the following activities take place using checklist for In-Situ Reinforced Concrete.
Formwork Requirements
Procurement of material for formwork and scaffolding to be synchronized with Contract programme.
The foreman shall ensure that formwork of required shape and size is fabricated.
Foreman shall ensure that no damage is caused to the shutters while lifting.
All safety precautions will be taken while lifting heavy shutters.
The foreman shall paint numbers on all panels in order to use them in correct positions against the formwork drawing.
Formwork fastened to previously cast concrete must be tightly fixed to prevent grout loss.
Over tightening of ties shall be avoided as they may fail when fully loaded.
The holes to be drilled in the formwork shall be neat so that they can be properly patched or plugged later on.
The props shall be in good condition and erected properly. It must be ensured that a minimum number of props are removed and are replaced, for access.
Props shall be in plumb and bearers shall not be off centre.
A prop shall not be used if it has any of these defects:
- a bend or crease in the tube
- corrosion other than light rusting on the surface
- a bent head or base plate
- an incorrect or damaged pin
Reinforcement
Reinforcement steel source certificates and test results as necessary shall be obtained, identified and filed by the Site Engineer.
Ensure reinforcement bar placement as per approved drawings.
Placing and Compacting Concrete
It is necessary to maintain proper speed depending upon total quantum of pour and site conditions. If placing speed is too slow, the concrete may stiffen forming cold joints and in case of rapid delivery, the work of placing may proceed ahead of the compacting gang making it impossible for them to do the concrete placement properly.
Impact of concrete on the formwork shall be avoided which could result in movement of reinforcement and lack of cover.
Forming of large heaps or sloping layers shall be avoided as these encourage segregation.
Inadequate compaction can seriously affect the quality of the concrete. Proper size of vibrator compatible with the formwork and Reinforcement shall be used.
The concrete layer being compacted shall never be deeper than the length of the poker head.
Ensure that the poker does not touch the formwork.
Otherwise it will cause poker burn’ and mark the surface of the finished concrete.
The poker shall not touch the reinforcement.
The vibration will be transmitted to concrete that has already stiffened and the bound between mix and the reinforcement could then be affected.
Striking the Formwork
Release agents as specified, are applied before concreting starts and before reinforcement is fixed each time that the form is used.
Formwork has to be struck as per the time period specified in the contract.
An earlier striking time may be authorized by the Engineer pending interim cube results or curing methods.
While striking formwork, necessary safety precautions must be adhered to.
Use hardwood wedges to remove the shutters entrapped with the concrete members and avoid use of nail bars to avoid damage to both concrete and the form.
Foreman must ensure cleaning of face of forms as soon as they have been struck.
Proper storage of formwork shall be ensured so that they are not damaged and easily identified when next required.
Check Sheet for In-Situ Reinforced Concrete
1. Check falsework design and issue permit to load.
2. Check quality of shutter lining for required finish.
3. Check formwork erected and restrained as per approved drawings
4. Check dimensions, line and level.
5. Check preparation of forms including support, tie rods, release agents, cleanliness.
6. Check plumbness and spacing of props.
7. Check tightness of bolts and wedges.
8. Check special built-in items, inserts, mechanical, electrical & plumbing embedments.
9. Check stop-ends, waterbar, dowels, flexcell etc.
10. Check bar placement as per approved bar bending schedule.
11. Check tie wires, spacers, cover.
12. Clean out loose material (tie-wires, nails etc.).
APPROVAL TO POUR
13. Check correct mix, slump, temp.
14. Check correct placing, compaction, grout loss control.
15. Take concrete test cubes and log.
16. Recheck line and level.
17. Protection against weather condition.
APPROVAL TO STRIKE
18. Check surface for blemishes.
19. Check cleanliness of forms after striking.