Soil Stabilization Methods – Mechanical and Chemical

Soil stabilization methods can be achieved either mechanically or chemically. In some cases, a combination of these two methods may be implemented.

Mechanical Soil Stabilization:

Mechanical stabilization is a physical process by which the physical properties of the soil structure is altered. Chemical stabilization uses additives to alter chemical properties, which will result in more stable soil.

Mechanical soil stabilization methods use compaction to interlock soil-aggregate particles. The soil particle size distribution must be such that a dense mass is produced when it is compacted. Stabilized soil can be obtained through uniform mixing followed by compaction. Additional fines or aggregates may be added to form well graded, dense soil-aggregate mixture. In some cases, geotextiles can be used to improve the engineering characteristics of the soil.

Chemical Soil Stabilization:

When it comes to chemical soil stabilization methods, cement can be used for a wide range of materials. However, the soil should have a plasticity index lower than 30. In the case of coarse-grained soils, the rate of grains passing a number 4 sieve (grains smaller than 4.76mm) should be greater than 45%.

Treatment with lime is among soil stabilization methods, which are effective in medium, moderately fine, and fine-grained soils. Its application results in decreased plasticity, increased workability and strength, and reduced swelling. Soil treated with lime gains strength slowly and requires approximately 14 days under hot weather conditions and 28 days under cool weather conditions to achieve significant strength. Unsurfaced soils treated with lime abrade rapidly under traffic movements, and thus paving is needed to prevent surface deterioration.

Fly ash consists mainly of silicon and aluminium compounds and is a common additive in chemical stabilizing mixes. It is a by-product of coal-fired, electric power-generation facilities. The quality of fly ash highly depends on the type of coal burned. Fly ash is categorized into two classes based on its calcium oxide (CaO) content. These are class C and class F.

• Class C fly ash has a significant content of CaO (i.e. more than 12%). It originates from sub-bituminous and lignite coal. Fly ash obtained through lignite combustion has the highest CaO content, often exceeding 30%. This kind of fly ash can be used as a stand-alone stabilizing agent. Class C fly ash, which has CaO content lower than 25%, needs lime to improve its performance.
• Class F fly ash has a low lime content (less than 10%). It originates from anthracite and bituminous coal. This kind of fly ash is not effective as a stabilizing agent by itself and thus has to be mixed with either lime or lime and cement to be able to stabilize soil.

All traditional soil stabilization methods require certain soil grading and weather conditions in order to be effective, thus limiting their applicability in practice. Stabilizing agents created by Global Road Technology do not have these kinds of limitations; they can be applied to the soil of any content and are equally effective under both cold and hot weather conditions. Unlike mechanical compaction, GRT soil stabilization methods result in waterproof soil body.

GRT stabilizers are so superior as they may be used in various applications such as:

• New construction – stabilization of subgrade, sub-base and base layers
• Pavement recycling – in situ binding of old crushed pavement to form a new one
• Sealing or stabilizing haul roads, side tracks, car parks, construction or military camps, container hardstands, railroad yards, and temporary landing areas.

For more information on Global Road Technology Soil Stabilization Methods – Mechanically or Chemically please Contact Us.