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Rising damp is the common term for the transport of water in the lower sections of walls and other ground-supported structures by capillary action in porous materials. [25] Although rising damp of up to 5 metres (20') in height has been observed [ 26 ] the height of rise is typically much lower and is rarely above 1.5 metres (5').
Mason, a tradesperson skilled variously in brick and blocklaying, concrete finishing (the placement, finishing, protecting and repairing of concrete in construction projects). [7] Also stonemason, marble setter and polisher, tile setter and polisher, terrazzo worker and finisher. Hod carrier is a subsidiary trade (also see Laborer).
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.
Sulfate attack typically happens to ground floor slabs in contact with soils containing a source of sulfates. [2] Sulfates dissolved by ground moisture migrate into the concrete of the slab where they react with different mineral phases of the hardened cement paste. The attack arises from soils containing SO 2−
It is estimated that a presence of 1% of muscovite in concrete reduces the strength of the internal bonding by 5%, and further that such blocks bond poorly with cement paste. [2] Mica also absorbs water, and excess water can cause problems in cold winters as the process of freezing and thawing damages the blocks. [ 2 ]
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:
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There are several other processes that can lead to intergranular fracture or preferential crack propagation at the grain boundaries: [8] [6] Microvoid nucleation and coalescence at inclusions or second phase particles located along grain boundaries; Grain boundary crack and cavity formations associated with elevated temperature stress rupture ...