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If rebars have been improperly installed or have inadequate concrete cover at surfaces exposed to the elements, oxide jacking and spalling can occur during the structure's lifetime: flat fragments of concrete are detached from the concrete mass as a result of the rebar's corrosion. Concrete, like most consolidated hard rocks, is a material very ...
Oxide jacking has caused concrete spalling on walls of the Herbst Pavilion at Fort Mason Center in San Francisco. The expansive force of rusting, which may be called oxide jacking or rust burst, is a phenomenon that can cause damage to structures made of stone, masonry, concrete or ceramics, and reinforced with metal components.
Rebar (short for reinforcement bar or reinforcing bar), known when massed as reinforcing steel or steel reinforcement, [1] is a tension device added to concrete to form reinforced concrete and reinforced masonry structures to strengthen and aid the concrete under tension. Concrete is strong under compression, but has low tensile strength.
When a concrete structure is designed, it is usual to specify the concrete cover for the rebar (the depth of the rebar within the object). The minimum concrete cover is normally regulated by design or building codes. If the reinforcement is too close to the surface, early failure due to corrosion may occur.
Concrete is poured around these plastic forms to create internal voids in the slab A voided biaxial slab installation in Turkey. Voided biaxial slabs, sometimes called biaxial slabs or voided slabs, are a type of reinforced concrete slab which incorporates air-filled voids to reduce the volume of concrete required.
Dowel bar retrofits, if done badly, can cause serious problems. These problems are usually due to poor workmanship and can be avoided by careful following of specifications and close supervision of workers. Use of heavy jackhammers (heavier than 14 kg class) tends to cause cracking of the concrete all around the slots.
A concrete slab is a common structural element of modern buildings, consisting of a flat, horizontal surface made of cast concrete. Steel- reinforced slabs, typically between 100 and 500 mm thick, are most often used to construct floors and ceilings, while thinner mud slabs may be used for exterior paving ( see below ).
Carbonatation induced rebar corrosion. Carbonatation is a slow process that occurs in concrete where lime (CaO, or Ca(OH) 2 ) in the cement reacts with carbon dioxide (CO 2) from the air and forms calcium carbonate. The water in the pores of Portland cement concrete is normally alkaline with a pH in the range of 12.5 to 13.5.