Editing Portland cement (section)

==Use==

[[File:Grosvenor estate, Westminster, London.jpg|thumb|Decorative use of portland cement panels on London's [[Grosvenor estate]]<ref>{{cite web|url=http://housingprototypes.org/project?File_No=GB017|title=Housing Prototypes: Page Street|work=housingprototypes.org|url-status=dead|archive-url=https://web.archive.org/web/20120916123622/http://housingprototypes.org/project?File_No=GB017|archive-date=16 September 2012|df=dmy-all|access-date=19 January 2007}}</ref>]]

The most common use for portland cement is in the production of concrete.<ref>U.S. Geological Survey, 2020, ''Mineral commodity summaries'' 200 p. {{doi|10.3133/mcs2020}}</ref> Concrete is a composite material consisting of [[Construction aggregate|aggregate]] ([[gravel]] and [[sand]]), cement, and water. As a construction material, concrete can be cast in almost any shape desired, and once hardened, can become a structural (load bearing) element. Concrete can be used in the construction of structural elements like panels, beams, and [[street furniture]], or may be [[Cast in place concrete|cast-''in situ'']] for superstructures like roads and dams. These may be supplied with concrete mixed on site, or may be provided with '[[ready-mixed]]' concrete made at permanent mixing sites. Portland cement is also used in [[Mortar (masonry)|mortar]]s (with sand and water only), for [[plaster]]s and [[screed]]s, and in [[grout]]s (cement/water mixes squeezed into gaps to consolidate foundations, road-beds, etc.).

When water is mixed with portland cement, the product sets in a few hours and hardens over a period of weeks. These processes can vary widely, depending upon the mix used and the conditions of [[Accelerated curing|curing]] of the product,<ref>{{Cite web |title=Portland Cement Strength – Pavement Interactive |url=https://pavementinteractive.org/reference-desk/materials/portland-cement/portland-cement-strength/ |access-date=2024-08-16 |language=en-US}}</ref> but a typical concrete sets in about 6&nbsp;hours and develops a [[compressive strength]] of 8&nbsp;MPa in 24&nbsp;hours. The strength rises to 15&nbsp;MPa at 3&nbsp;days, 23&nbsp;MPa at 1&nbsp;week, 35&nbsp;MPa at 4&nbsp;weeks, and 41&nbsp;MPa at 3&nbsp;months. In principle, the strength continues to rise slowly as long as water is available for continued hydration, but concrete is usually allowed to dry out after a few weeks and this causes strength growth to stop.