Techniques Of Soil Stabilization

Soil stabilization is a process of pulverizing natural soil, mixing it with chemical additive and compacting the mixture. The chemical additive can either be a cement or lime. The process is performed with soil stabiliser in order to increase the strength of the soil and its bearing capacity, while at the same time, decreasing the water sensitivity. This helps diminish the volume change during wet or dry cycles. Soil stabilization provides a flat base or sub-base for any type of paved area and to improve the conditions of the foundations. Many different types of soil stabilisers and few techniques can be used to achieve good stabilization.

Soil Stabilization With Cement

Soil stabilization with cement is one of the two basic techniques and is performed using cement, soil stabiliser and compaction equipment. A soil stabiliser mixes the existing pavement with certain amount of cement. Any type of soil can be stabilized with this technique. There are soils that do not react well to cement because of their high organic content and their hardening may take longer. The thickness of a cement base depends on traffic volume and stability of the sub-grade. If the thickness is more than 15 cm, it is built in layers.

Although all types of soils can be stabilized with cement, the more granular materials pulverize easily and require less amount of cement. Pulverization is an essential step when stabilizing heavy-type soils to break the soil particles and ensure contact with the cement. For this technique, various compaction equipment and soil stabilisers can be used, including cement spreaders, cement meters, single or multiple shaft, windrow-type mixes and others. The cost of soil stabilization with cement varies and mostly depends on the amount of cement, thickness, type of job and type of soil.

Soil Stabilization With Lime

This soil stabilization technique can be used with either high-calcium and high-magnesium lime. The hydrated lime (high-calcium) is more widely used, although their soil-stabilizing ability is almost equal. The soil stabilizer for this technique mixes the existing pavement with water and spread lime on-place and it is very beneficial. The bearing capacity of the soil to be stabilized should be determined before and after the process, in order to find out the optimum amount of lime adequate for the job. Today, there are several techniques of lime soil stabilization with different types soil stabilisers, but the process is the same:

• grading the area
• pulverizing, spreading lime
• adding water during preliminary mixing
• preliminary curing
• final rotary mixing, and
• pulverizing and compacting.

Lime should not be spread dry during cold weather conditions, but sprinkled with water to reduce dust. During the preliminary mixing, heavy watering is suggested, because it can distribute the lime to the correct depth. The compaction is the final step and it needs to be done to at least 93% of the maximum density. More water can be added before the compacting process begins to reach the correct amount of moisture content.