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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]
Curing is intended to maintain moist conditions at the surface of concrete. It can be done by letting the formworks in place for a longer time, or by applying a hydrophobic thin film of an oily product (curing compound) at the concrete surface (e.g., for large slabs or rafts) to minimize water evaporation. Drying shrinkage
These are created during concrete mixing (while the slurry is in its liquid state), with most surviving to remain part of it when hardened. Air entrainment makes concrete more workable [1] during placement, and increases its durability when hardened, particularly in climates subject to freeze-thaw cycles. [2] It also improves the workability of ...
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]
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On the other hand, for completely dry concrete, the chemical reaction of carbonation cannot occur. Another influencing factor for CO 2 diffusion rate is concrete porosity. Concrete obtained with higher w/c ratio or obtained with an incorrect curing process presents higher porosity at hardened state, and is therefore subjected to a higher ...
An 11-year-old girl who was taken to a hospital in critical condition after attempting to save her 12-year-old classmate's life when he fell through the surface of an icy upstate New York lake has ...
A man living in Southern California has been accused of shipping guns, thousands of rounds of ammunition and other military items to North Korea in shipping containers.