RC repair
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Project: xxx STANDARD METHOD STATEMENT FOR CONCRETE REPAIR A. SURFACE HONEYCOMB (less than 50mm depth) – no rebar exposed 1. Identify the area of defective concrete needed for repair 2. Chisel away the defective concrete by chisel/ handheld electrical breaker. Ensure that all loose concrete is removed properly and that sound concrete remains. 3. Clean the concrete surface with brush and ensure that it is free from dust. 4. The final surface should be damp to ensure good bonding with the new concrete. 5. Patch the repair area with the approved non-shrink material. B. SURFACE HONEYCOMB - with rebar exposed, area less than 200x200mm 6. Identify the area of defective concrete needed for repair 7. Chisel away the defective concrete by chisel/ handheld electrical breaker. 8. Hack away the loose concrete until the whole visible rebar is fully exposed. 9. Clean the concrete surface with brush and ensure that it is free from dust. 10. The final surface should be damp to ensure good bonding with the new concrete. 11. Close up the affected area with 12mm thk plywood. Provide small opening at top of formwork for grouting. (refer Sketch-A) Page 1 of 6
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Method Statements for RC Repair
Transcript of RC repair
STANDARD METHOD STATEMENT OF RECTIFICATION FOR CONCRETE HONEYCOMB
Project: xxxSTANDARD METHOD STATEMENT FOR CONCRETE REPAIR
A. SURFACE HONEYCOMB (less than 50mm depth) no rebar exposed
1. Identify the area of defective concrete needed for repair
2. Chisel away the defective concrete by chisel/ handheld electrical breaker. Ensure that all loose concrete is removed properly and that sound concrete remains.
3. Clean the concrete surface with brush and ensure that it is free from dust.
4. The final surface should be damp to ensure good bonding with the new concrete.
5. Patch the repair area with the approved non-shrink material.
B. SURFACE HONEYCOMB - with rebar exposed, area less than 200x200mm
6. Identify the area of defective concrete needed for repair
7. Chisel away the defective concrete by chisel/ handheld electrical breaker.
8. Hack away the loose concrete until the whole visible rebar is fully exposed.
9. Clean the concrete surface with brush and ensure that it is free from dust.
10. The final surface should be damp to ensure good bonding with the new concrete.
11. Close up the affected area with 12mm thk plywood. Provide small opening at top of formwork for grouting. (refer Sketch-A)
12. Insert sponge to seal up the gap between the formwork and the concrete surface.
13. Prepare the non-shrink grout mix according to manufacturers recommendation.
14. Pour in the non-shrink grout from the opening provided.
15. Ensure that the formwork is maintained for at least 24 hrs before stripping.
16. Trim away the excess concrete at the grout opening area.
Sketch - A
C. SURFACE HONEYCOMB - with rebar exposed, depth less than 50mm
17. Identify the area of defective concrete needed for repair
18. Chisel away the defective concrete by chisel/ handheld electrical breaker.
19. Hack away the loose concrete until the whole visible rebar is fully exposed.
20. Clean the concrete surface with brush and ensure that it is free from dust.
21. The final surface should be damp to ensure good bonding with the new concrete.
22. Close up the affected area with 12mm thk plywood. Secure the formwork firmly to the concrete surface with M10 anchor bolts or with other external supports, to prevent leakage due to pressure grouting.
23. Insert sponge to seal up the gap between the formwork and the concrete surface.
24. Install 16mm rubber tube at the bottom and top of void.
25. Seal up the formwork sides using mortar cement and allow drying.
26. Prepare approved pressure grout according to manufacturers recommendation.
27. Using pressure equipment, slowly pump in the grout from the bottom tube. (If grout is seen leaking out from the formwork sides, stop the injection and patch up the leakage spots with fast setting hydraulic cement. Allow the cement to set for 1 minute. Proceed with the grouting once the hydraulic cement is set)
28. When the grout is seen flowing out from the top tube, stop the pumping and seal up the upper tube.
29. Maintain the pressure of minimum 10 psi for at least 1 minute.
30. Seal up the bottom tube and then remove the pressure pump.
31. Ensure that the formwork is maintained for at least 24 hrs before stripping.D. SEVERE HONEYCOMB (more than 50mm depth)32. Rectification procedure similar to C, except to fill up the voids with aggregate packed with chicken wire mesh before proceeding to steps 6.E. BULGING / MISALIGNED CONCRETE SURFACE (repair thickness less than 25mm)33. Identify and mark the position.
34. Pull a plump to determine the required depth to trim (where applicable)
35. Hack the concrete using hand held electrical breaker.
36. After hacking, check the alignment again.
37. After the concrete is trimmed to the required depth, clean the surface of concrete with brush.
38. The final surface should be damp to ensure good bonding with the new concrete.
39. Prepare the approved polymer modified mortar mix according to manufacturer recommendation.
40. Patch the repair area with polymer modified mortar
41. (For serious misalignment, separate PE proposal shall be submitted for approval)F. SURFACE CRACK42. Cut V-groove of minimum depth of 10mm to 20mm along the crack line.
43. Clean the groove with brush and ensure it is free from dust.
44. The final surface should be damp to ensure good bonding with the new concrete.
45. Patch the repair area with the approved non-shrink material.
REPAIR MATERIALS
Non-shrink Grout from HDB approved list1. Davco Ready Grout 280
2. E Mix PE Non-Shrink Grout
3. Quickseal 510Pressure Grout from HDB approved list1. Davco BC High Grade Grout
2. E.Mix PG Non Shrink GroutPolymer Modified Mortar from HDB approved list1. Davco Polycrete
2. Ready Durarepair 320
3. Quickseal 514 Easi PatchQuick Setting Hydraulic Cement1. Quickseal 516Formwork
Honey comb < 200 x200mm
Opening for pouring of non-shrink grout mix
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