Concrete is liable to crack in both the plastic and hardened states due to stresses which it intrinsically sustains by the nature of its constituent materials. The construction industry does not readily accept that these intrinsic cracks are almost as inevitable as structural cracks, and concrete containing them may often be summarily and unjustifiably condemned.
Cracks may be regarded as a failure if they
- are aesthetically unacceptable;
- make the structure non-watertight;
- affect the durability of the structure;
- are structurally significant.
Repair Tecniques
Epoxy resins have become the most used material for injecting dormant cracks and is the preferred material because:
- which will harden in wet conditions and adhere to moist concrete.
- Excellent adhesion to fresh and hardened concrete.
- low curing shrinkage.
- have good mechanical strength in the presence of water and are resistant to a wide range of chemicals, including alkalis and aggressive
ground water.
Positive displacement piston dispenser is used to inject epoxy resin into cracks. It is important when pressure injecting to use the minimum pressure necessary to make the resin flow into the crack. Excessive pressure is likely to force the resin along the path of least resistance, hence leaving voids.