What is the difference between cement and concrete?
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. The aggregates are sand and gravel or crushed stone; the paste is water and portland cement. Concrete gets stronger as it gets older. Portland cement is not a brand name, but the generic term for the type of cement used in virtually all concrete, just as stainless is a type of steel and sterling a type of silver. Cement comprises from 10 to 15 percent of the concrete mix, by volume. Through a process called hydration, the cement and water harden and bind the aggregates into a rocklike mass. This hardening process continues for years meaning that concrete gets stronger as it gets older.
It’s simple. Concrete is used for the finished products, such as sidewalks, foundations, and the surface of many roads. Concrete contains sand, gravel and cement. Cement is the special hardening ingredient (the gray powder) that makes concrete harden. Cement is usually made of 60% lime (limestone), 25% silica, 5% alumina, and 10% other materials, such as gypsum and iron oxide. (Content provided by the Mineral Information Institute, 2002 www.mii.
Cement correctly refers to Portland Cement by itself – a dry powder. Concrete is something made by mixing Portland Cement with aggregates such as sand and gravel and adding water. When you buy materials, you can get sacks of Portland Cement, sand, and gravel, and mix your own concrete. Or you can buy a sack of concrete mix, which has all the dry ingredients so that you can just add water.
Many people, even construction professionals, use these two terms interchangeably. But cement and concrete are two very different materials. Simply, cement is the white or gray powder that is the essential ingredient in concrete. Concrete is the solid mass, produced by mixing cement, water and aggregates (sand and rock) together in specified ratios. When water mixes with the cement, special reactions occur that make an incredibly strong and durable solid. The aggregates are trapped within the cement and water mixture as it sets and hardens. Other materials are sometimes added to achieve desired results such as color, resistance to chemical attack or workability. Portland cement denotes a cement that is made to exacting standards, set by ASTM. One hundred years ago, people all over North America began to experience the benefits of portland cement and the concrete made with it. Ads for cement sidewalks, cement houses and factories, and cement bridges and streets, peppered newspapers, mag
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