Concrete is a composite material composed of aggregate bonded together with a fluid cement that cures over time. Concrete is the second-most-used substance in the world after water, and is the most widely used building material. Its usage worldwide, ton for ton, is twice that of steel, wood, plastics, and aluminium combined.
A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel (aggregate) together. Cement mixed with fine aggregate produces mortar for masonry, or with sand and gravel, produces concrete. Concrete is the most widely used material in existence and is behind only water as the planet's most-consumed resource.
Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar, stucco, and non-specialty grout. It was developed from other types of hydraulic lime in England in the early 19th century by Joseph Aspdin, and is usually made from limestone. It is a fine powder, produced by heating limestone and clay minerals in a kiln to form clinker, grinding the clinker, and adding 2 to 3 percent of gypsum. Several types of portland cement are available. The most common, called ordinary portland cement (OPC), is grey, but white portland cement is also available. Its name is derived from its resemblance to portland stone which was quarried on the Isle of Portland in Dorset, England. It was named by Joseph Aspdin who obtained a patent for it in 1824. His son William Aspdin is regarded as the inventor of "modern" portland cement due to his developments in the 1840s. The term portland in this context refers to a material or process, not a proper noun like a place or a person, and should not be capitalized.
A concrete mixer is a device that homogeneously combines cement, aggregate, and water to form concrete. A typical concrete mixer uses a revolving drum to mix the components. For smaller volume works, portable concrete mixers are often used so that the concrete can be made at the construction site, giving the workers ample time to use the concrete before it hardens. An alternative to a machine is mixing concrete by hand. This is usually done in a wheelbarrow; however, several companies have recently begun to sell modified tarps for this purpose.
Ready-mix concrete (RMC) is concrete that is manufactured in a batch plant, according to each specific job requirement, then delivered to the job site "ready to use".
Cast stone or reconstructed stone is a highly refined building material, a form of precast concrete used as masonry intended to simulate natural-cut stone. It is used for architectural features: trim, or ornament; facing buildings or other structures; statuary; and for garden ornaments. Cast stone can be made from white and/or grey cements, manufactured or natural sands, crushed stone or natural gravels, and colored with mineral coloring pigments. Cast stone may replace such common natural building stones as limestone, brownstone, sandstone, bluestone, granite, slate, coral, and travertine.
Cement kilns are used for the pyroprocessing stage of manufacture of portland and other types of hydraulic cement, in which calcium carbonate reacts with silica-bearing minerals to form a mixture of calcium silicates. Over a billion tonnes of cement are made per year, and cement kilns are the heart of this production process: their capacity usually defines the capacity of the cement plant. As the main energy-consuming and greenhouse-gas–emitting stage of cement manufacture, improvement of kiln efficiency has been the central concern of cement manufacturing technology. Emissions from cement kilns are a major source of greenhouse gas emissions, accounting for around 2.5% of non-natural carbon emissions worldwide.
Blue Circle Industries was a British public company manufacturing cement. It was founded in 1900 as the Associated Portland Cement Manufacturers Ltd through the fusion of 24 cement works, mostly around on the Thames and Medway estuaries, together having around a 70% market share of the British cement market. In 1911, the British Portland Cement Manufacturers Ltd was formed by the addition of a further 35 companies, creating a company with an initial 80% of the British cement market.
Cement clinker is a solid material produced in the manufacture of portland cement as an intermediary product. Clinker occurs as lumps or nodules, usually 3 millimetres (0.12 in) to 25 millimetres (0.98 in) in diameter. It is produced by sintering limestone and aluminosilicate materials such as clay during the cement kiln stage.
Portland is a town in the Central Tablelands of New South Wales, Australia. At the 2016 census, Portland had a population of 2,424 people. The town was named after Australia's first cement works.
White Portland cement or white ordinary Portland cement (WOPC) is similar to ordinary, gray Portland cement in all aspects except for its high degree of whiteness. Obtaining this color requires substantial modifications to the method of manufacturing. It requires a much lower content in colored impurities in the raw materials used to produce clinker: low levels of Cr2O3, Mn2O3, and Fe2O3), but above all, a higher temperature is needed for the final sintering step in the cement kiln because of the higher melting point of the mix depleted in iron oxides. Because of this, the process is more energy demanding and the white cement is somewhat more expensive than the gray product.
Rosendale cement is a natural hydraulic cement that was produced in and around Rosendale, New York, beginning in 1825. From 1818 to 1970 natural cements were produced in over 70 locations in the United States and Canada. More than half of the 35 million tons of natural cement produced in the United States originated with cement rock mined in Ulster County, New York, in and around the Town of Rosendale in the Hudson River Valley. The Rosendale region of southeastern New York State is widely recognized as the source of the highest quality natural cement in North America. The Rosendale region was also coveted by geologists, such as W. W. Mather, a geologist working for the State of New York, for its unusual exposed bedrock. Because of its reputation, Rosendale cement was used as both a trade name and as a generic term referring to any natural hydraulic cement in the US. It was used in the construction of many of the United States' most important landmarks, including the Brooklyn Bridge, the pedestal of the Statue of Liberty, Federal Hall National Memorial, and the west wing of the United States Capitol building.
Eco-Cement is a brand-name for a type of cement which incorporates reactive magnesia, another hydraulic cement such as Portland cement, and optionally pozzolans and industrial by-products, to reduce the environmental impact relative to conventional cement. One problem with the commercialization of this cement, other than the conservatism of the building industry, is that the feedstock magnesite is rarely mined.
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass.
Polysius AG is a German company and subsidiary of ThyssenKrupp Technologies that manufactures cement plants and builds cement mills, cement kilns, cement factory automation systems and ore grinding facilities. Polysius is active around the world, constructing, installing and managing cement and ore processing plants.
Cement City Historic District is a historic district in Donora, Pennsylvania. The district includes 80 Prairie School concrete residences built in 1916–17. The homes served as housing for employees of the American Steel and Wire Company. Poured-in-place concrete houses had become popular in large-scale housing developments at the time, partly thanks to promotion by Thomas Edison; the homes built in Donora used a newly patented construction method from the Lambie Concrete House Corporation. Building the houses required a combined 10,000 barrels of Portland cement.
The Edison Ore-Milling Company was a venture by Thomas Edison that began in 1881. Edison introduced some significant technological developments to the iron ore milling industry but the company ultimately proved to be unprofitable. Towards the end of the company's life, Edison realized the potential application of his technologies to the cement industry and formed the Edison Portland Cement Company in 1899.
The versatility of concrete has led to its appearance in numerous non-traditional formats such as furniture, sculpture and art.
The cement industry in the United States produced 82.8 million tonnes of cement in 2015, worth US$9.8 billion, and was used to manufacture concrete worth about US$50 billion. The US was the world's third-largest producer of cement, after China and India. The US cement industry includes 99 cement mills in 34 states, plus two plants in Puerto Rico. The industry directly employed 10,000 workers in 2015. Ten percent of the cement used in the United States in 2015 was imported.
Lafarge Africa Plc is a cement manufacturer headquartered in Lagos and quoted on the Nigerian Stock Exchange. It is majorly controlled by the Holcim Group. Previously trading under the name of Lafarge Wapco Plc, the merger of Lafarge and Holcim and resulting consolidation of Lafarge's assets in Nigeria and South Africa resulted in the name change to Lafarge Africa.
