Concrete is a heterogeneous mixture made up of cement, water and small rock particles. It is not a homogeneous mixture, so it cannot be considered a pure substance as a pure substance is made of one element or compound.
A homogeneous mixture is a mixture that has a uniform composition throughout its whole volume. A heterogeneous mixture is a mixture that differs from one point to another.
Heterogeneous mixtures are a type of suspension. An example of a suspension is a solution of sugar in water.
The main difference between a homogeneous and a heterogeneous mixture is that the latter does not get completely dissolved in water. In the case of a heterogeneous mixture, the materials are not mixed together and do not form any chemical bonds.
It is a heterogeneous mixture because the ingredients are not always evenly distributed in the mix and can even vary from one part of the mixture to the other. However, despite its heterogeneity, it still gets hard and performs its function of providing structural integrity for structures.
There are many types of concrete mixes, each with a different set of requirements and capabilities. For instance, lightweight concrete is used in constructions where strength is not a primary requirement. This type of concrete is a good choice for a wide range of applications as it can be poured without the need for any reinforcement.