Concrete

Concrete was used for first time in 3000BC, by Romans and then for Egypt. The Romans used concrete in colosseum and pantheon. The ingredients of this material are sand, cement, water, air and gravel; the cement is to create a solid mass, water to make hydrate and solidify cement. The ancestor used the concrete because their fireproof and weatherproof and the concrete can be molds to any shape. But with advance the human notice that concrete is strong in compression but low in tensile strength, and was funded a solution to low tensile strength. Was invented the Reinforced concrete; is concrete with steel, because steel is strong in tensile strength while concrete is strong in compressive. We can find the __concrete-shell construction,__ which permits the erection of vast vaults and domes with a concrete and steel content reduced that the thickness is comparatively less than that of an eggshell. The second develop was the __precast-concrete construction__ which employs bricks, slabs, and supports made under optimal factory conditions to increase waterproofing and solidity, to decrease time and cost in erection, and to reduce expansion and contractions . And finally, __prestressed concrete,__ which provides bearing members into which reinforcement is set under tension to produce a live force to resist a particular load . Other way that uses the concrete is the tilt up constructions, which walls are poured directly at the jobsite in large slabs of concrete called “tilt up panels” or "tilt wall panels”. In the precast concrete used a prefabricated wall panels, mean while the tilt up panels are fabricate in the construction.   Types of constructions with concrete:    Reinforced concrete    Precast concrete    Prestressed concrete    Concrete shell