Concrete is composed of aggregates, which can be any or a combination of sand, gravel or rocks that is held together by cement. The cement itself, when mixed with water, serves as a paste that holds all the components of the concrete together once the cement sets and hardens.Know More
One of the earliest evidence of manmade concrete were the floors of royal palace of Tiryns in Greece, which was constructed around 1400 to 1200 B.C. The ancient Romans were one of the most prolific users of concrete, using the material for their architectural and other construction works.
During a 700-year period between 300 B.C. to 476 A.D., the Romans used a concrete material called opus caementicium that was made from pumice as an aggregate with pozzolana and quicklime as cement. Modern-day analysis show that opus caementicium had similar compressive strength to modern Portland cement. However, since the Romans did not use any reinforcements, opus caementicium had significantly lower tensile strength compared to modern reinforced cement.
The proportions of the materials used for making modern-day concrete varies according to its application. For example, the proportions used on concrete for floors, driveways and sidewalks is ideally one part cement, two and half parts sand and three parts gravel. On the other hand, the recommended concrete mix proportions for high strength floors and columns is one part cement, one part sand and two parts gravel.Learn more about Building Materials
Cement is a fine, gray powder that is used as a construction binding material. When mixed with water, cement reacts chemically and becomes hard and strong. Cement is categorized as either hydraulic or nonhydraulic, depending on how it mixes with water.Full Answer >
Tricalcium silicate, also called alite, is one of the most abundant compounds found in cement and has the chemical formula Ca3SiO4. Its shorthand formula is C3S. Another abundant compound in cement is dicalcium silicate, which has the formula Ca2SiO5, or C2S in shorthand.Full Answer >
The typical ratio to mix cement is approximately 10 to 15 percent cement, 60 to 75 percent aggregate, and 15 to 29 percent water. In many concrete mixes, entrained air may take up another 5 to 8 percent.Full Answer >
Cement hardens through a process called hydration. This process begins when water is mixed in with cement and an aggregate such as gravel or crushed limestone is added to form concrete.Full Answer >