Case 1 – Alkali-Silica Reaction
Navigation
- Introduction
- Causes of Defects
- Good Practices
- Standards
- Maintenance and Diagnostics
- Remedial
- Similar Cases
- References
Remedial
The steps to repairing ASR are [1, 13-14]:
- Arrest the external source of water ingress. If the concrete is kept dry, then the expansive reaction by the gel can be halted. Hence it is necessary to waterproof the surfaces and also to avoid any water being trapped within the concrete. The waterproofing coating must allow water to evaporate out of the concrete whilst preventing liquid water from entering. One of the best waterproofing coatings is concrete itself, applied as relatively thin layer usually by pneumatic projection (guniting).
- If the structure is monitored that expansion is still continuing, the first step is to eliminate or minimise the exposure of the structure to water.
- The drainage of the structure should be improved so that water drains away from the structure rather than onto or through or down parts of the structure. Areas that can trap or hold water should be eliminated. This will also prevent corrosion of rebars initiated by the ingress of water.
- Fill the macrocracks with a cement grout or resin and improve the surface appearance by a surface coating. This can further reduce moisture ingress.
- If ASR has affected the integrity of the structure, post stressing can be used to restore the integrity. Loads carried by the structure may also need to be reduced.