This article was accepted into the corpus but its outbound wikilinks were never NER-processed — typical at the deepest BFS hop or when the run's entity cap was reached. No expansion funnel to show.
| Concrete | |
|---|---|
| Classification | Building material |
| Composition | Cement, aggregates, water, admixtures |
| Invented | Ancient times |
| Inventor | Various cultures |
Concrete
Concrete is a composite construction material made primarily from cement, aggregates, and water, widely used in infrastructure, architecture, and engineering. It underpins transportation projects like Panama Canal, Golden Gate Bridge, and urban landmarks in cities such as New York City, London, and Tokyo. Engineers, architects, and institutions including American Society of Civil Engineers, Royal Institution of Chartered Surveyors, and International Union of Laboratories and Experts in Construction Materials, Systems and Structures develop standards, while firms like Bechtel Corporation, Skanska, and Vinci SA execute large-scale projects.
The origins trace to ancient builders in civilizations such as Ancient Rome, Ancient Egypt, and the builders of Mohenjo-daro, who used lime- and volcanic ash–based binders for durable works like the Pantheon (Rome), the Great Pyramid of Giza, and city drains in the Indus Valley Civilization. In the 18th and 19th centuries innovations by figures and entities including John Smeaton, the British Army, and companies like Portland Cement Company led to modern hydraulic binders; the naming of Portland cement followed the work of Joseph Aspdin. The industrial era saw adoption in projects by contractors and engineers such as Gustave Eiffel and firms involved in canal and railway works, culminating in 20th-century milestones including the construction of Hoover Dam and urban renewal programs led by agencies like the Tennessee Valley Authority.
Concrete consists of a binder (commonly Portland cement), fine and coarse aggregates (sand, gravel, crushed stone), water, and chemical or mineral admixtures supplied by manufacturers and distributors such as CEMEX and LafargeHolcim. Variants include reinforced concrete used by firms like Skanska in high-rise work; prestressed concrete employed in bridges by companies like Vinci SA; high-performance and ultra-high-performance concretes specified by research centers such as Massachusetts Institute of Technology and Darmstadt University of Technology; lightweight concretes in projects by Nippon Steel; and geopolymer concretes studied at institutions including Imperial College London and Chinese Academy of Sciences.
Mechanical, physical, and chemical properties are characterized by standards from organizations like ASTM International, British Standards Institution, and European Committee for Standardization. Compressive strength, tensile strength, modulus of elasticity, creep, and shrinkage are measured using test methods developed in laboratories at National Institute of Standards and Technology and university civil engineering departments such as University of Cambridge. Durability assessments consider freeze–thaw resistance, chloride penetration, and alkali–silica reaction evaluated in interlaboratory studies coordinated by entities like International Federation for Structural Concrete.
Raw materials are quarried by companies such as Vulcan Materials Company and processed at plants owned by conglomerates like Holcim. Cement kilns operated by industrial groups including HeidelbergCement produce clinker that is ground into cement. Ready-mix operations supplied by regional firms deliver concrete to sites for placement by contractors working with equipment manufacturers like Putzmeister and Schwing. Techniques include slipforming used in projects overseen by engineers at Skidmore, Owings & Merrill, shotcrete applied in tunneling by companies such as Bechtel Corporation, and pumped concrete enabling construction of tall structures for developers including Tishman Speyer.
Longevity is addressed through design guidance from bodies like American Concrete Institute and through interventions by municipal agencies in cities like Chicago and Los Angeles. Common deterioration mechanisms—corrosion of reinforcement, sulfate attack, freeze–thaw damage, and carbonation—are mitigated using protective coatings produced by manufacturers such as Sherwin-Williams and cathodic protection systems used in infrastructure maintained by authorities like Transport for London. Rehabilitation techniques include epoxy injection, external post-tensioning executed by specialist firms, and replacement strategies employed in major repairs of structures such as the Sydney Harbour Bridge.
Cement production contributes greenhouse gas emissions quantified by studies from organizations including Intergovernmental Panel on Climate Change and International Energy Agency. Mitigation approaches—supplementary cementitious materials like fly ash sourced from utilities such as Southern Company, ground granulated blast-furnace slag supplied by steelmakers like ArcelorMittal, carbon capture technologies piloted by firms like Carbon Clean, and low-carbon cements developed at research centers including ETH Zurich—are pursued globally. Lifecycle assessment and circular economy practices promoted by the World Resources Institute and urban sustainability programs in cities such as Copenhagen and Singapore encourage material reuse, recycled aggregates, and alternative binders to reduce embodied emissions.
Concrete is used in foundations, dams, roads, runways, tunnels, towers, and buildings by developers like Skanska, China State Construction Engineering Corporation, and Fluor Corporation. Iconic concrete structures include the Pantheon (Rome), Hoover Dam, Itaipu Dam, the hulls of works engineered by firms such as Arup Group, and modern skyscrapers designed by architects at practices like Foster + Partners and Zaha Hadid Architects. Transport infrastructure including the Channel Tunnel and major airports such as Hartsfield–Jackson Atlanta International Airport feature extensive concrete engineering and ongoing research collaborations with universities like University of California, Berkeley.
Category:Building materials