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Therefore, when concreting at cold temperature cannot be avoided, it is essential to have a minimum curing time at a temperature sufficiently above the freezing point of the concrete pore water, so that the early strength of concrete is high enough to resist the inner tensile stress caused by water freezing. [5]
A slab of pykrete Pykrete is made of 14% sawdust and 86% water by mass.. Pykrete (/ ˈ p aɪ k r iː t /, PIE-creet) [1] is a frozen ice composite, [2] originally made of approximately 14% sawdust or some other form of wood pulp (such as paper) and 86% ice by weight (6 to 1 by weight).
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
The ultimate strength of concrete is influenced by the water-cementitious ratio (w/cm), the design constituents, and the mixing, placement and curing methods employed. All things being equal, concrete with a lower water-cement (cementitious) ratio makes a stronger concrete than that with a higher ratio. [2]
Concrete has a total embodied energy of 1.69 GJ/tonne, lower per unit mass than most common building materials besides wood. However, concrete structures often have high masses, so this comparison is not always directly relevant to decision making. Additionally, this value is based only on mix proportions of up to 20% fly ash.
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Air entrainment in concrete is the intentional creation of tiny air bubbles in a batch by adding an air entraining agent during mixing. A form of surfactant (a surface-active substance that in the instance reduces the surface tension between water and solids) it allows bubbles of a desired size to form.
A precast concrete walled house under construction An example of low-quality precast concrete with exposed dowels, connectors, indications of cracks, and malformations, even during its installation, Barangay Lantic, Carmona, Cavite, Philippines Interior view of the walls, supports, and roof of a precast commercial shop in Williston, North Dakota, US.