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When water is added to cement, each of the compounds undergoes hydration and contributes to the final state of the concrete. [2] Only calcium silicates contribute to the strength. Tricalcium silicate is responsible for most of the early strength (first 7 days). [3] Dicalcium silicate, which reacts more slowly, only contributes to late strength.
Portland cement clinker was first made (in 1825) in a modified form of the traditional static lime kiln. [2] [3] [4] The basic, egg-cup shaped lime kiln was provided with a conical or beehive shaped extension to increase draught and thus obtain the higher temperature needed to make cement clinker.
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 that of steel, wood, plastics, and aluminium combined. [3]
Foam concrete, also known as lightweight cellular concrete or foamed cement, is a cement-based material that incorporates stable air bubbles to create a lightweight and highly insulating product. Unlike air-entrained concrete, which introduces tiny air bubbles through an admixture during mixing, foam concrete replaces coarse aggregates with ...
Manufacturing costs were therefore considerably higher, but the product set reasonably slowly and developed strength quickly, thus opening up a market for use in concrete. The use of concrete in construction grew rapidly from 1850 onward, and was soon the dominant use for cements. Thus Portland cement began its predominant role.
The most common use for portland cement is in the production of concrete. [17] Concrete is a composite material consisting of aggregate (gravel and sand), cement, and water. As a construction material, concrete can be cast in almost any shape desired, and once hardened, can become a structural (load bearing) element.
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]
Pre-tensioned concrete is a variant of prestressed concrete where the tendons are tensioned prior to the concrete being cast. [1]: 25 The concrete bonds to the tendons as it cures, following which the end-anchoring of the tendons is released, and the tendon tension forces are transferred to the concrete as compression by static friction.