Concrete

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= = = = = Concrete is a composite construction material composed primarily of aggregate cement and water. Exist since the year 3000 BF, it was invented at Egypt, and after that concrete have be changing by the time. This material is strong in compression and weak in tension. =

= Concrete has relatively high compressive strength, but much lower tensile strength. For this reason is usually reinforced with materials that are strong in tension (often steel). The elasticity of concrete is relatively constant at low stress levels but starts decreasing at higher stress levels as matrix cracking develops. Concrete has a very low coefficient of thermal expansion and shrinks as it matures. All concrete structures will crack to some extent, due to shrinkage and tension. Concrete that is subjected to long-duration forces is prone to creep. =

= Definition  = = Concrete is a manufactured mixture of cement and water, with aggregates of sand and stones, which hardens rapidly by chemical combination to a stonelike, water-and-fire-resisting solid of great compressive but low tensile strength. = = Because it can be poured into forms while liquid to produce a great variety of structural elements, it provides an economical substitute for traditional materials, and it has the advantages of continuity (absence of joints) and of fusing with other materials. =

= Reinforced concrete was developed to add the tensile strength of steel to the compressive strength of mass concrete. It was invented (1849) by Joseph Monier, who received a patent in 1867. He exhibited his invention at the Paris Exposition of 1867. =



= = = Precast-concrete construction, 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. =



= = = Prestressed concrete provides bearing members into which reinforcement is set under tension to produce a live force to resist a particular load. Since the member acts like a spring, it can carry a greater load than an unstressed member of the same size. =



= Concrete-shell construction permits the erection of vast vaults and domes with a concrete and steel content so reduced that the thickness is comparatively less than that of an eggshell. =



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= What is the difference between tiltwall construction, tilt-up panel construction and pre-cast concrete construction? = = Tilt-up and tiltwall are two terms used to describe the same process. = = For a tilt-up concrete building, the walls are created by assembling forms and pouring large slabs of concrete called panels directly at the job site. The panels are then tilted up into position around the building's slab. Because the concrete tiltwall forms are assembled and poured directly at the job site, no transportation of panels is required. One major benefit of this is that the size of the panels is limited only by the needs of the building and the strength of the concrete panels themselves. = = Tiltwall panels can sometimes be extremely wide and/or tall. Tilt-up panel have been measured at just over 69 feet across and almost 93 feet from top to bottom. Thus, architects and tilt-up concrete contractors have a great deal of flexibility in planning and creating their buildings. = = Tilt-up or tiltwall construction and precast concrete are similar processes. Because tilt-up affords more flexibility, it is the method of choice in locations where the weather allows it. Precast concrete is a suitable choice in circumstances where environmental factors and the construction schedule preclude tiltwall as a viable option. =

= Conclusion  = = = = The importance of concrete in modern society cannot be overestimated. Look around you and you will find concrete structures everywhere such as buildings, roads, bridges, and dams. There is no escaping the impact concrete makes on your everyday life. The is an important material of construction for us, without him we could not have the structures that we have today. =