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Concrete has a very low coefficient of thermal expansion, and as it matures concrete shrinks. All concrete structures will crack to some extent, due to shrinkage and tension. Concrete which is subjected to long-duration forces is prone to creep. The density of concrete varies, but is around 2,400 kilograms per cubic metre (150 lb/cu ft). [1]
Concrete hardens as a result of the chemical reaction between cement and water (known as hydration and producing heat). For every mass (kilogram, pound, or any unit of weight) of cement (c), about 0.35 mass of water (w) is needed to fully complete the hydration reactions. [1]
Mass concrete is defined by American Concrete Institute Committee 207 as "any volume of concrete with dimensions large enough to require that measures be taken to cope with the generation of heat from the hydration of cement and attendant volume change to minimize cracking."
Cement board is composed of aggregated Portland cement with a glass-fiber mesh on the surfaces. This 5 ⁄ 16 inch (7.9 mm) thick cement board is designed as an underlayment for tile floors. These are 3-by-5-foot (91 by 152 cm) sheets.
By contrast, if a beam's weight is fixed, its cross-sectional dimensions are unconstrained, and increased stiffness is the primary goal, the performance of the beam will depend on Young's modulus divided by either density squared or cubed.
The characteristic strength is defined as the strength of the concrete below which not more than 5% of the test results are expected to fall. [ 16 ] For design purposes, this compressive strength value is restricted by dividing with a factor of safety, whose value depends on the design philosophy used.
As of May 2020, CIMERWA produced four types of portland cement; namely 1. SUREBUILD, a 42.5N premium cement meant for heavy construction projects 2. SURECEM, a 32.5N all-purpose cement ideal for concrete, mortar, plaster and brick joinery 3. SUREROAD, another 32.5N product, is a custom-made cement meant for road construction and 4.
Regular concrete is the lay term for concrete that is produced by following the mixing instructions that are commonly published on packets of cement, typically using ...