Cement is a very important material in building construction. Although the terms cement and concrete often are used interchangeably, cement is actually an ingredient of concrete. Concrete is basically a mixture of aggregates and paste.
Twice as much concrete is used in construction around the world than the total of all other building materials. Slightly more than half of all low-rise buildings in the United States are constructed from concrete. The annual global production of concrete is about 5 billion cubic yards. The Global production of cement in 2000 was 1.56 billion tones, one-third of this was produced in China alone.
Concrete is often the most economical choice. The material's ability to weather hurricanes and tornadoes and its resistance to insects are valued. Builders also select concrete for its fire resistance. Four methods of concrete construction are commonly used to create load-bearing walls for low-rise construction. They are tilt-up, precast, concrete masonry, and cast-in-place.
Cements used in construction can be characterized as being either hydraulic or non-hydraulic. Hydraulic cements harden because of hydration, a chemical reaction between the anhydrous cement powder and water. Thus, they can harden underwater or when constantly exposed to wet weather. The chemical reaction results in hydrates that are not very water-soluble and so are quite durable in water.
Non-hydraulic cements do not harden underwater, like slaked limes harden by reaction with atmospheric carbon dioxide. Green cement is a cementitious material that meets or exceeds the functional performance capabilities of ordinary cement by incorporating and optimizing recycled materials, thereby reducing consumption of natural raw materials, water, and energy, resulting in a more sustainable construction material. The manufacturing process for green cement succeeds in reducing and even eliminating the production and release of damaging pollutants and greenhouse gasses, particularly Carbon-dioxide.
The most important uses of cement are as an ingredient in the production of mortar in masonry, and of concrete, a combination of cement and an aggregate to form a strong building material. For the world capacity to produce cement in 2010, the top three producers were China, India, and USA accounting for just under half the world total capacity.