1) One of the disadvantages of conventional concrete is the high self weight of concrete, density of normal concrete is in order of 2200 to 2600 $kg/m^3$. This heavy self weight will make it to some extent and uneconomical structural material.

2) Attempt have been made in the past to reduced the self weight of concrete to increase the efficiency of concrete as a structural material.

3) The light weight concrete as we call in a concrete whose density various from 300 to 1850 $kg/m^3$.

4) There are many advantages of having low density. It help to reduce dead load, increase the progress of building, and lower haulage and handling cost.

5) The weight of building is an important factor for design, particularly in weak soil and tall structure. In frame structure beam and column have to carry load of floor and wall. If floor and wall made up by light weight concrete it will result in considerable economy.

6) Most important characteristic of light weight concrete is the relatively low thermal conductivity, a property which improves with decreasing density.

Advantages of lightweight concrete

Following are the advantages of light weight concrete

1) The local industrial waste if found suitable for lightweight concrete,can be economically utilized.

2) The reduction in weight of concrete helps easy removal transport and erection of precast product.

3) The lightweight concrete has comparatively less tendency to spall. Hence it fire resistance is greater as compare to ordinary concrete.

4) Lightweight concrete has lower thermal expansion than ordinary concrete.