Methods of soil stabilizations

Methods of soil stabilizations

In this article, I discussed various methods used to stabilize soil in detail.

Soil stabilization methods can be grouped into two categories:

(a) Modification or Improvement of Existing Soil Properties:

1. Compaction
2. Drainage

(b) Modification Using Admixtures (Mechanical Stabilization, Bitumen, Lime, Cement, Chemical, Electrical, Thermal Stabilization).

Stabilization of Soil:

(i) Mechanical Stabilization:

This involves two main operations:

1. Altering the composition of soil by adding or removing specific constituents.
2. Densification or compaction.

(ii) Cement Stabilization:

Soil stabilized with cement is known as soil cement.

The required amount of cement ranges from 5-15% by weight of dry soil.

For sand, it's 7-15%, for silt, it's 12-15%, and for clay, it's 12-20%.

(iii) Lime Stabilization:

The addition of lime to soil leads to two chemical reactions:

1. Alteration in the nature of absorbed layers through the base exchange.
2. Cementing or pozzolanic action.

Lime reduces the plasticity index of highly plastic soil, increases the optimum moisture content, decreases compacted density, and enhances strength and durability.

Generally, 2-8% of lime is needed for coarse-grained soil, and 5-10% for plastic soil.

(iv) Bitumen Stabilization:

Bituminous material added imparts binding or waterproofing action or both to the soil.

Based on the action and soil type, bitumen stabilization is further classified into categories like soil bitumen, sand bitumen, waterproof mechanical stabilization, and oiled earth.

(v) Chemical Stabilization:

Calcium chloride: Functions as a flock foaming reagent, aiding soil compaction.

Sodium chloride: Like calcium chloride, it retains moisture and reduces evaporation.

Sodium silicate: Used in combination with other chemicals like CaCl2 and NaCl for soil stabilization.

(vi) Thermal Stabilization:

Heating fine-grained soil to 400-600°C causes irreversible changes in clay minerals.

The soil becomes non-plastic, less sensitive to water, and non-expansive.

(vii) Electrical Stabilization:

Increasing the stability or shear strength of fine-grained soil by passing a direct current through it.

This process is also known as electro-osmosis.