The process of improving the engineering properties of soils is called soil stabilization. It is the simplest method of soil stabilization. By soil stabilization, the soil becomes more stable by the reduction in the permeability and compressibility and by the increase in shear strength. With the increase in soil stabilization properties the bearing capacity of soil is increased significantly.
The various method of soil stabilization includes:
- Mechanical Stabilization
- Cement Stabilization
- Lime Stabilization
- Bitumen Stabilization
- Stabilization by Geo-textiles
In this method changing the gradation of virgin soil stabilizes the soil. To do this two or more types of soils are mixed to attain a desired property to suit a particular construction.
For mechanical stabilization, the soils are grouped into two categories. They comprise aggregates and binders. Aggregates are sands and gravels and binders are silts and clays. When mixed together in a definite proportion, a soil possessing required internal friction and cohesion is obtained. When properly placed and compacted, the material becomes mechanically stable.
The various factors, which affect the mechanical stability of a mixed soil, comprise strength of aggregate, mineral composition, gradation, and plasticity characteristics.
Mechanical stabilization is generally used to improve the sub-grade of low bearing capacity. It is extensively used in the construction of bases, sub-bases and surfacing of the roads.
In cement stabilization pulverized soils and cement in suitable proportion are mixed with water and the resulting mixture is compacted by compacting equipment such as rollers. The material obtained by mixing cement and soil is called soil-cement. When cement hydrates and develops strength the soil cement becomes a hard and durable structural material.