Concrete is a composite construction material composed primarily of aggregate, cement, and water. There are many formulations, which provide varied properties. The aggregate is generally a coarse gravel or crushed rocks such as limestone, or granite, along with a fine aggregate such as sand. The cement, commonly Portland cement, and other cementitious materials such as fly ash and slag cement, serve as a binder for the aggregate. Various chemical admixtures are also added to achieve varied properties. Water is then mixed with this dry composite, which enables it to be shaped (typically poured) and then solidified and hardened into rock-hard strength through a chemical process called hydration. The water reacts with the cement, which bonds the other components together, eventually creating a robust stone-like material. Concrete has relatively high compressive strength, but much lower tensile strength. For this reason it is usually reinforced with materials that are strong in tension (often steel). Concrete can be damaged by many processes, such as the freezing of trapped water.
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Some articles on concrete:
... Approximately 6,650 tons of structural steel, 80,000 cubic yards of concrete, and 7000 cubic tons of reinforcing steel bars went into its construction ... The complex sits on a series of reinforced concrete grade beams tied to 150 concrete caissons as much as ten feet in diameter and to a depth of 80 feet ... The exterior columns and beams are concrete encased steel wide flanges surrounded by reinforcing bars ...
... There were 300 households out of which 37.0% had children under the age of 18 living with them, 45.3% were married couples living together, 14.3% had a female householder with no husband present, and 33.7% were non-families. 27.7% of all households were made up of individuals and 11.7% had someone living alone who was 65 years of age or older ...
... Culverts may be made of concrete, galvanized steel, aluminum, or plastic, typically high density polyethylene ... For example, open-bottom corrugated steel structures are often built on concrete footings, or corrugated ... Plastic culvert liners are also inserted into failing concrete or steel structures in order to repair the structure without excavating and closing the road ...
... Concrete concepts have perceptible attributes they can be physically seen or proven ... Concrete concepts are usually easier for a child to understand ... to a child can be difficult because it is hard to change it into a concrete concept ...
... Carbonatation is a slow process that occurs in concrete where lime (calcium hydroxide) in the cement reacts with carbon dioxide from the air and forms calcium carbonate ... The water in the pores of Portland cement concrete is normally alkaline with a pH in the range of 12.5 to 13.5 ... Carbon dioxide will start to carbonatate the cement in the concrete from the moment the object is made ...
More definitions of "concrete":
- (adj): Capable of being perceived by the senses; not abstract or imaginary.
Example: "Concrete objects such as trees"
- (adj): Formed by the coalescence of particles.
- (verb): Form into a solid mass; coalesce.
- (verb): Cover with cement.
Example: "Concrete the walls"
Famous quotes containing the word concrete:
“To step over the low wall that divides
Road from concrete walk above the shore
Brings sharply back something known long before
The miniature gaiety of seasides.”
—Philip Larkin (19221986)
“Experience and imagination must enter into the very constitution of our thoughts involving concrete individuals.”
—Zeno Vendler (b. 1921)
“freeways fifty lanes wide
on a concrete continent
spaced with bland billboards
illustrating imbecile illusions of happiness”
—Lawrence Ferlinghetti (b. 1919)