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Concrete shrinks as it cures. It can shrink 1 ⁄ 16 inch (1.6 mm) over a 10-foot long area (3.05 meters). This causes stress internally on the concrete and must be accounted for by the engineers and finishers placing the concrete, and may require the use of steel reinforcement or pre-stressed concrete elements where this is critical.
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] Reinforced concrete is the most common form of concrete.
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 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.
Chegg began trading shares publicly on the New York Stock Exchange in November 2013. [15] Its IPO was reported to have raised $187.5 million, with an initial market capitalization of about $1.1 billion. [16] In 2014, Chegg entered a partnership with book distributor Ingram Content Group to distribute all of Chegg's physical textbook rentals ...
Their addition allows to decrease the water-to-cement ratio of concrete or mortar without negatively affecting the workability of the mixture. It enables the production of self-consolidating concrete and high-performance concrete. The water–cement ratio is the main factor determining the concrete strength and its durability. Superplasticizers ...
The parts are in terms of weight – not volume. For example, 1-cubic-foot (0.028 m 3) of concrete would be made using 22 lb (10.0 kg) cement, 10 lb (4.5 kg) water, 41 lb (19 kg) dry sand, 70 lb (32 kg) dry stone (1/2" to 3/4" stone). This would make 1-cubic-foot (0.028 m 3) of concrete and would weigh about 143 lb (65 kg). The sand should be ...
A field extension L/K is called a simple extension if there exists an element θ in L with L = K ( θ ) . {\displaystyle L=K(\theta ).} This means that every element of L can be expressed as a rational fraction in θ , with coefficients in K ; that is, it is produced from θ and elements of K by the field operations +, −, •, / .