Concrete, also known as beton, is a material made from cement, sand and water with an aggregate such as crushed stone or gravel (ready-mix concrete plant). It is one of the most important modern building materials, particularly when steel is added to make reinforced concrete. The Romans were the first to use plain concrete in history, around 2,000 years ago. They used it in most of their buildings because it was easy to shape and could be placed by workers with basic training.
Concrete is a mixture of raw materials consisting of sand, gravel or crushed stone, and cement, with water added (ready-mix concrete plant). When thoroughly mixed, the materials bond through the setting process.
Concrete has many properties that distinguish it from other materials. It gradually becomes solid and strong over time, beginning with initial set and ending with final set (ready-mix concrete plant). It strongly resists compressive stress but has very low tensile resistance. For that reason, plain, unreinforced concrete is never used where tensile stresses occur, such as in beams.
To overcome this problem, steel is added because it resists both tensile and compressive forces very well. Although long steel bars can carry tensile forces, concrete cannot carry all compressive forces when its sections are slender, creating the possibility of buckling in the concrete member.
A composite mixture of concrete and steel therefore provides an ideal material for resisting the different stresses acting on it. This composite is known as reinforced concrete (ready-mix concrete plant).