Limestone, clay, sand and/or shale.
Portland cement's chemistry comes to life in the presence of water. Cement and water form a paste that coats each particle of stone and sand—the aggregates. Through a chemical reaction called hydration, the cement paste hardens and gains strength. The paste, composed of portland cement and water, coats the surface of the fine (small) and coarse (larger) aggregates. Through a chemical reaction called hydration, the paste hardens and gains strength to form the rock-like mass known as concrete. What is Concrete: Concrete & Cement Defined. Contrary to popular belief, concrete and cement are not the same thing; cement is actually just a component of concrete. Concrete is made up of three basic components: water, aggregate (rock, sand, or gravel) and Portland cement. Cement, usually in powder form, acts as a binding agent when mixed with water and aggregates. Portland Cement-The cement and water form a paste that coats the aggregate and sand in the mix. The paste hardens and binds the aggregates and sand together. Water-Water is needed to chemically react with the cement (hydration) and too provide workability with the concrete. How Concrete is Made. In its simplest form, concrete is a mixture of paste and aggregates, or rocks. The paste, composed of portland cement and water, coats the surface of the fine (small) and coarse (larger) aggregates. Through a chemical reaction called hydration, the paste hardens and gains strength to form the rock-like mass known as concrete. How Cement is Made. Portland cement is the basic ingredient of concrete. Concrete is formed when portland cement creates a paste with water that binds with sand and rock to harden. Cement is manufactured through a closely controlled chemical combination of calcium, silicon, aluminum, iron and other ingredients. See an overview of the cement manufacturing process in this 7-minute animation. Learn about the basic ingredients of concrete, mix designs, and types of cement. Contrary to popular belief, concrete and cement are not the same thing; cement is actually just a component of concrete. Concrete is made up of three basic components: water, aggregate (rock, sand, or gravel) and Portland cement. Cement, usually in powder form, acts as a binding agent when mixed with water and aggregates. This combination, or concrete mix, will be poured and harden into the durable material with which we are all familiar. Many cement manufacturers make Portland Cement. Portland cement, the basic ingredient of concrete, is a closely controlled chemical combination of calcium, silicon, aluminum, iron and small amounts of other ingredients to which gypsum is added in the final grinding process to regulate the setting time of the concrete. A cement is a binder, a substance that sets and hardens and can bind other materials together. The word cement can be traced back to the Roman term opus caementicium, used to describe masonry resembling modern concrete that was made from crushed rock with burnt lime as binder. The most important uses of cement are as a component in the production of mortar in masonry, and of concrete, a combination of cement and an aggregate to form a strong building material. Cement is a fine, soft, powdery-type substance. It is made from a mixture of elements that are found in natural materials such as limestone, clay, sand and/or shale. When cement is mixed with water, it can bind sand and gravel into a hard, solid mass called concrete.  Concrete is a composite material composed of aggregate bonded together with a fluid cement which hardens over time. Most use of the term concrete refers to Portland cement concrete or to concretes made with other hydraulic cements, such as ciment fondu. However, road surfaces are also a type of concrete, asphaltic concrete, where the cement material is bitumen. Concrete production is the process of mixing together the various ingredients—water, aggregate, cement, and any additives—to produce concrete. Concrete production is time-sensitive. Once the ingredients are mixed, workers must put the concrete in place before it hardens.
http://www.cement.org/cement-concrete-basics/how-concrete-is-made http://www.concretenetwork.com/concrete.html http://www.cement.org/cement-concrete-basics/how-concrete-is-made http://www.cement.org/cement-concrete-basics/how-cement-is-made http://www.concretenetwork.com/concrete/whatis/ https://en.wikipedia.org/wiki/Cement http://www.buildeazy.com/newplans/eazylist/cement.html https://en.wikipedia.org/wiki/Concrete
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