Case 2

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Remedial (see also Remedial)

For cases that suffer from differential movement, please see Strengthening using Underpinning and/or Fibrewrapping.

  • It is important to determine if the cracks are live or not.
  • Live cracks must be treated as movement joints whereas dead cracks can be grouted or covered over.
  • If the cracks are only at the surface, cosmetic repair methods can be used, such as:
  • These repair techniques are limited to dormant cracks. The two most commonly used methods for non-structural cracks are epoxy injection and pressure grouting. The last two methods are used for active cracks. This means that these cracks will continue to grow and if arrested at its present location will propagate at another location.
  • Flexible sealing not only seals the crack but also allows continued movement at the location by allowing the crack to function as a movement joint. Stitching, on the other hand, does not close the crack but but prevents it from growing further.
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  • For cracks that are less fine (less than 0.2mm wide) and hidden from public view, the process or autogenous healing should be allowed to take place. Autogenous healing relies on the inherent ability of the concrete to heal itself, it is applicable for closing dormant cracks in moist environment. Concrete repair by stitching is able to aid in autogenous healing of concrete.
  • Materials that can be used are as follows:
    • Cements – ordinary or rapid hardening Portland cement
    • Epoxide resins
    • Polyester resins
    • Rubber latex
    • Polyvinyl acetate
    • Surface Penetrating Sealants