Soil stabilization can be achieved by pulverizing the natural soil or borrow material, mixing in
a chemical additive, and thoroughly compacting the mixture. The additive can be either portland
cement, lime or salt (sodium chloride).
For stabilizing soils with cement, nearly all soil types can be used, from gravelly and sandy to
fine-grained silts and clays. Generally, the more granular materials are used because they pulverize
and mix readily and require the least amount of cement. Waste and sub-standard materials found
at aggregate plants, old gravel road and street materials, as well as cinders and slag, make
excellent soil cement, if they contain 55 percent or more gravel passing the No. 4 sieve. The
method calls for these steps: grade area; scarify, pulverize and prewet soil as necessary; regrade;
spread portland cement and mix; apply water and mix; compact; final grade; and cure.
For stabilizing soils with lime, hydrated lime (calcium hydroxide) is mainly used. There are two
basic types of lime: high calcium and high magnesium. Their soil stabilizing ability is roughly
equal. Soils ranging in Plasticity Index from 10 to 50 plus are suitable for lime stabilization. If the
soil has a low Index value, it is essential for the soil to contain at least 15 percent of material
passing a minus No. 200 mesh. Conventional large are stabilization calls for these steps: grade
area; scarify and pulverize; spread lime; add water during preliminary mixing; rough grade with
light compaction; preliminary cure; final rotary mix and pulverize; compact; final cure.
Salt stabilization applies to treating base aggregates for road work or parking lot areas. It has not
yet been tired for improving foundation soil. The proper procedure to follow for in place
stabilization with salt is as follows: scarify to desired depth; apply salt; apply water; mix; compact;
grade; water and roll; and cure.