What is the difference between concrete and cement?

Concrete and cement are two terms people often get confused about having the same meaning and use for various purposes. People often say “cement sidewalk” or “cement mixer,” but the proper terms are supposed to be “concrete sidewalk” and “concrete mixer.” While it may look harmless using these words interchangeably, it is still technically incorrect to utilize them. Even though both concrete and cement are construction materials, they are actually two distinct products.

Cement is one of the ingredients of the mixture that creates concrete. The substance is primarily made up of lime and silica, and those two materials constitute about 85% of the materials found in cement. Other ingredients used to form cement include calcium, iron, aluminum, and a few others. These materials are mixed and heated in big kilns at a very high temperature, ranging from 2,700°F to 3000°F, and it will eventually form a product known as clinkers. These clinkers are small pellets that resemble marbles, and they are usually ground into a finely powdered form with gypsum often added for extra durability. The final product of this mixture is what we call as cement. When water is added to the cement, a chemical process takes place, thus allowing it to harden. The cement then acts as a binding product that helps to hold the materials of concrete together.

There are two types of cement utilized for construction, and they are called hydraulic and non-hydraulic. Hydraulic cement uses water to begin a chemical reaction that hardens the mixture and allowing it to become water-resistant. This type of cement is suitable for wet conditions, underwater structures, or any places where the cement may frequently come into contact with water. On the other hand, non-hydraulic cement doesn’t harden when mixed with water, which makes this type unsuitable for most conditions. Non-hydraulic cement dries on its own when exposed to the carbon dioxide, a compound that is typically found in the air. Because it needs carbon dioxide to stay as a solid material, it is not advisable to use non-hydraulic cement on areas where there is not enough air, such as closed areas, sewers, or underwater passages. Non-hydraulic is also the first form of cement before the invention of the hydraulic type during the 18th century.

The most prevalent type of cement in the world is the Portland cement, officially known as Ordinary Portland Cement (OPC). Portland cement is the generic name for the class of hydraulic cement used in construction. It was developed by Englishman Joseph Aspdin in the 18th century, and its name is derived from Portland stone, a limestone formation that has a similar appearance to hydraulic cement and is quarried in the Isle of Portland located in Dorset, England. Portland stone is one of the most popular construction materials in England before cement came into the picture. Portland cement is often classified into eight types, which are different from each other in terms of specifications.

As mentioned previously, concrete is a material created from a mixture of cement, water, and other aggregates that makes it solid and durable. These aggregates include crushed and mostly chemically inert materials like stones, gravel, and sand. The type and the number of aggregates put into the mixture vary according to the application of concrete in construction. The aggregates also usually make up 60% to 80% of the mixture. Cement constitutes for about 15% of the total mass of concrete, and the latter cannot be made without the former since the cement is what binds all the materials or ingredients together to form concrete. The ratio of water to cement is very important as well, as the amount determines the strength of concrete. If there is too much water in the mix, the concrete will weaken and will not be suitable for constructing structures.

Concrete is today one of the most used construction materials, mainly due to its strength, durability, and resistance to both fire and water. Another reason for the material’s popularity is that it gets stronger over time because it continues to harden. It is difficult to find a house or a structure that doesn’t use cement nowadays, and in the future, the number of no cement buildings may become zero.

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