CRACKS special subjects è Visible damage If there is such damage, it is easy for moisture and dirt to penetrate with sure result in the gradual carbonization and disintegration of the concrete. Undoubtedly and in most cases, the building structure will require repairs within a few years of its construction. The causes of the damage and the occurrence of damage should be identified and remedied before proceeding with any additional action to protect the building. Concrete slabs are often waterproofed on the surface. Thus, the defective concrete under the waterproofing coat(s) has not undergone the proper preparation for the restoration of the imperfections (sealing - stabilization of the substrate) that pre-existed in the concrete slab. The main causes of these defects are generally due to inadequacies in design or construction practices (failures, omissions, bad workmanship, etc.). è Small imperfections They are typically very thin gaps caused by large capillaries resulting from the use of low-strength concrete with a high ratio of water to cement. Hairline cracks generally exist in concrete and their presence may be due to several reasons. There is not a serious threat for damage and deterioration of strength initially as they are generally superficial and they tend not to continue. But with the passage of time, because of temperature variations and changes in the weather conditions as well as changes in loading conditions (addition of weight in load-bearing structural elements) these cracks increase in depth, length and width and combine with other thin cracks. They create a continuous passage for moisture, chlorides, sulfates, and other chemicals from the environment, which enter and initiate the corrosion of steel in concrete while having other harmful reactions. In conclusion, both the apparent damage as well as any and all small imperfections in the concrete are harmful to the ‘health’ of the buildings. They can cause the degradation of concrete, depending on the extent of their presence, the environmental conditions of the area where the building is located, and the maintenance performed during its life cycle. However, obvious problems can cause faster deterioration and greater damage, (due to their size mostly), to the building than small imperfections. 72 Repair & Renovation Guide
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