In this article, we would have a look on the different types of concrete. There are different classification systems to categorize the types of concrete including, for example, the unit weight, compressive strength and what additives exist in the mixture. Let us overview the three basic classification systems.
Classification According to the Unit Weight
Based on the unit weight, concrete can be divided into four categories:
Heavy-weight concrete: this type of concrete is used for the construction of special kinds of structures such as laboratories, radioactive plants so on. The unit weight of heavyweight concrete is larger than 3200 kg/m3.
Normal-weight concrete: this type of concrete commonly used in normal structural applications such as buildings, pavements, and other types of regular structures. The density of the normal weight concrete is approximately 2400 kg/m3.
Lightweight concrete: this concrete can be used in both non-structural and structural members depending on its composition but in most cases, it would be applied in the non-structural elements. The unit weight varies between 1200 up to 1800 kg/m3.
Ultralightweight concrete: it can only be used for the construction of non-structural members. This means it can’t be used in beams, slabs, columns or any other load bearing element. The density of this concrete is less then 1200 kg/m3.
It should be noted that the main component that is responsible for determining the unit weight of concrete is the aggregate. Let us say for now that there are four types of aggregates according to their unit weight which corresponds to the four types of concrete.
Classification According to Compressive Strength
Again, concrete can be divided into four types according to the compressive strength:
Low strength concrete: this concrete has a compressive strength below 20 MPa. In most cases, builders use it to build subgrades of roads, partitions and buildings and mass concrete structures.
Moderate strength concrete: this is the most commonly used type of concrete for buildings, bridges, pipelines, pavements etc. the strength of this concrete varies between 20 to 50 MPa.
High strength concrete: it has a strength from 50 to 150 MPa, thus, engineers choose this type for the construction of tall buildings, bridges tower, and shear walls.
Ultra high strength concrete: this concrete was mainly applied under lab conditions, but it has not been widely applied in field structures. Its strength is about 150 MPa.
Classification According to Additives
We know that the basic components of concrete are cement, water, fine aggregate, and coarse aggregate. In some cases, other materials are added to concrete to give it an additional feature. Depending on the type of material added, concrete can be classified into various types.
For example, fiber reinforced concrete is a concrete with fibers added to the mixture. There are different types of fibers such as steel, glass, and carbon. Adding fibers to concrete provides it with higher toughness, tension strength, better shrinkage control, and or better finishing. If instead of fibers, polymers are added to concrete, concrete becomes ”Polymer concrete”. Polymers are added to concrete in three different ways: binder, impregnation, as admixture. Thus, depending on the type of addition, concrete can be categorized into different types.