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Example of flat piece of concrete having dislodged with corroded rebar underneath, Welland River bridge across Queen Elizabeth Way in Niagara Falls, Ontario. The expansion of the corrosion products (iron oxides) of carbon steel reinforcement structures may induce internal mechanical stress (tensile stress) that cause the formation of cracks and disrupt the concrete structure.
Autogenous self-healing crack. Self-healing concrete is characterized as the capability of concrete to fix its cracks on its own autogenously or autonomously. It not only seals the cracks but also partially or entirely recovers the mechanical properties of the structural elements. This kind of concrete is also known as self-repairing concrete.
Cracked walls: Cracks may be horizontal, vertical, diagonal or stair-stepped. Severe pressure or structural damage is evident by widening cracks. Buckling walls: Usually caused by hydrostatic pressure. Walls appear to be bowed inward. Peeling paint: Water seeping through walls may lead to bubbling or peeling paint along basement walls. [4]
Autogenous healing is the natural ability of cementitious materials to repair cracks. This ability is principally attributed to further hydration of unhydrated cement particles and carbonation of dissolved calcium hydroxide. [105] Cementitious materials in fresh-water systems can autogenously heal cracks up to 0.2 mm over a period of 7 weeks. [106]
Dowel bar retrofit (DBR) is a process that re-establishes load transfer capability on joints and cracks by installing epoxy-coated, round steel dowels into existing concrete pavement across transverse joints and/or cracks. Slots are cut using diamond-tipped saw blades; the existing concrete is removed and the dowels are placed in the slots ...
Masonry walls are built with a damp-proof course to prevent rising damp, and the concrete in foundations needs to be damp-proofed or waterproofed with a liquid coating, basement waterproofing membrane (even under the concrete slab floor where polyethylene sheeting is commonly used), or an additive to the concrete.
A dowel bar retrofit (DBR) is a method of reinforcing cracks in highway pavement by inserting steel dowel bars in slots cut across the cracks. It is a technique which several U.S. states' departments of transportation have successfully used in repairs to address faulting in older jointed plain concrete pavements.
When a reinforced concrete member is put in tension, after cracking, the member elongates by widening of cracks and by formation of new cracks. Figure 1 Formation of internal cracks. Ignoring the small elastic strain in the concrete between the cracks, we can relate the crack width to the strain of the member by: