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Causes of Damage to Concrete-construction defects

Some of the concrete damages caused by construction defects such as honeycombs, rock pockets, form failure, dimensional errors, and finishing defects.

Honeycombs or rock pockets are voids left due to the failure of cement paste to fill the area around aggregates. Honeycombs can form as a result of poor compaction of concrete and low workability of concrete. Honeycombs, if minor, can be repaired and filled with mortar, but repairing has to be done within 24 hours removal of form. If the repairing of damaged concrete delayed to more than 24 hours after the form removal or the honeycombs is extensive. The damaged area should be prepared, and the damaged concrete should be removed. Then the repairing materials will be applied to the prepared area. 

Figure 1

Improper supporting of formwork can result in form movement and sometimes form bulging, this type of defects, if a minor, can be repaired by concrete grinding. But if the form movement is significant, the concrete member shall be removed and replaced. Dimensional error is another type of construction defect, and it usually occurs. If the dimensional error doesn’t affect the structure, it can be accepted. But if the change in member will reduce the structural capacity or distort the aesthetic of the structure. Then errors shall be corrected by removing the defective concrete and replacing it with epoxy-bonded concrete or replacement concrete.

Finishing defects involve over-finishing or add water to concrete during the finishing stage. The result concrete surface will be highly porous, permeable, and low durability. Poorly finish surfaces will exhibit concrete spalling at the early stage of their service life. The spalling of concrete can be repaired by removing the damaged concrete and replaced with epoxy-bonded concrete. If the deterioration of concrete detected at an early stage, it could be repaired by coating concrete with sealing compounds, which reduce the concrete porosity and permeability.


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