Methods of soil stabilization

Soil stabilization is the process of improving the engineering properties of soil (strength, bearing capacity, permeability, volume stability) by mechanical or chemical means.

Mechanical methods

1. Mechanical (granular) stabilization: blending two or more soils of different gradation, such as coarse sand or gravel with clay, to get a well-graded mixture with higher density and strength.
2. Compaction: densifying the soil by rolling, tamping or vibration in layers at OMC. Rollers (smooth wheel, sheepsfoot, pneumatic) are used for surface layers.
3. Deep compaction: dynamic compaction, vibroflotation and compaction piles are used for deep loose sands.
4. Preloading, drainage and reinforcement: surcharge loading, sand drains, and geotextiles or geogrids.

Chemical methods

1. Cement stabilization: cement hydration binds particles. It is suitable for sandy soils.
2. Lime stabilization: lime reduces plasticity and swelling and gives pozzolanic strength gain. It is suitable for clays.
3. Bituminous stabilization: bitumen or cutback/emulsion waterproofs and binds the soil particles.
4. Chemical admixtures: calcium chloride, sodium silicate and fly ash are mixed for special effects.
5. Grouting: cement or chemical grout is injected into voids or fissures to bind and seal the soil.

Mechanical methods change the physical arrangement of particles, while chemical methods change the bonding between particles.