Soil stabilisation

Summary

Soil stabilisation - is the binding of the particles within a subgrade in order to improve its mechanical properties.

Technical Information

Soil stabilisation is an important tool for improving the quality of a weak subgrade. It can improve the strength of certain soils by factors greater than 10. It is also relatively cheap in most cases so it is widely practised across the world.

Soil stabilisation is achieved by turning the soil into a hydraulically bound mixture (HBM). This involves either:

Adding a hydraulic binder and water to the soil, such as Portland cement or a pozzolan mixed with lime. This is the most common method and can be used for most soils.

Adding lime and water to the soil. This method only applies to reactive soils which are capable of a pozzolanic reaction in the presence of lime.

The process for soil stabilisation is as follows:

Soil samples are taken to a lab and tested.
Based on the results from the lab, a soil ‘mix design’ is produced, which determines how much binder or lime is required per m2 of soil surface.
The correct amount of binder or lime is added to the surface of the soil, mixed with water, and mixed with the soil to an appropriate depth in-situ.
The HBM is allowed to cure for the appropriate amount of time.
The HBM is mixed again after sufficient curing, and then tightly compacted.

One of the main advantages of soil stabilisation is that it doesn’t require the import of fill material as it just uses the locally available material.