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Tremie. A tremie is a watertight pipe, usually of about 250 mm inside diameter (150 to 300 mm), [ 1 ] with a conical hopper at its upper end above the water level. It may have a loose plug or a valve at the bottom end. A tremie is usually used to pour concrete underwater in a way that avoids washout of cement from the mix due to turbulent water ...
A single concrete block, as used for construction. Concrete is a composite material composed of aggregate bonded together with a fluid cement that cures to a solid over time. Concrete is the second-most-used substance in the world after water, [ 1 ] and is the most widely used building material. [ 2 ] Its usage worldwide, ton for ton, is twice ...
The water–cement ratio (w/c ratio, or water-to-cement ratio, sometimes also called the Water-Cement Factor, f) is the ratio of the mass of water (w) to the mass of cement (c) used in a concrete mix: The typical values of this ratio f = w⁄c are generally comprised in the interval 0.40 and 0.60. The water-cement ratio of the fresh concrete ...
Gypsum concrete is a building material used as a floor underlay [ 43 ] used in wood-frame and concrete construction for fire ratings, [ 43 ] sound reduction, [ 43 ] radiant heating, [ 44 ] and floor leveling. It is a mixture of gypsum, Portland cement, and sand. [ 43 ] One of its advantages is the lightweight nature.
The first concrete was poured into the dam on June 6, 1933, 18 months ahead of schedule. [64] Since concrete heats and contracts as it cures, the potential for uneven cooling and contraction of the concrete posed a serious problem. Bureau of Reclamation engineers calculated that if the dam were to be built in a single continuous pour, the ...
Sea water contains by weight approximately 3.5% salts. These salts include sodium chloride, magnesium sulfate, calcium sulfate, and bicarbonates. In water these salts dissociate in free ions (Na +, Mg 2+, Cl −, SO 2− 4, HCO − 3) and migrate with the water into the capillaries of the concrete. Chloride ions, which make up about 50% of ...
H2SO4 + Ca (OH)2 → CaSO4 · 2H2O. When concrete is carbonated by atmospheric carbon dioxide (CO 2), or if limestone aggregates are used in concrete, H2SO4 reacts with calcite (CaCO3) and water to also form gypsum while releasing CO 2 back to the atmosphere: H2SO4 + CaCO3 + H2O → CaSO4 · 2H2O + CO2.
Properties of concrete. Concrete has relatively high compressive strength (resistance to breaking when squeezed), but significantly lower tensile strength (resistance to breaking when pulled apart). The compressive strength is typically controlled with the ratio of water to cement when forming the concrete, and tensile strength is increased by ...
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