It was deemed that 10% to 12% calcium oxide (CaO) in stabilizers was optimum for stabilizing expansive soils. Test results indicated that cement was preferable for higher strength at shorter curing times (7 days), while lime produced the maximum strength at longer curing periods (90 days). Specimens were subjected to Atterberg limits (LL/PI), pH, unconfined compressive strength, and volumetric swell tests. Three different soils with variable sulfate contents were treated with Type I/II portland cement, lime, Class C fly ash (FA), and Class C FA-cement and Class F FA-cement blends. In this paper, the effectiveness of different chemical stabilizers in improving the engineering properties of expansive soils is investigated. However, presence of deleterious compounds such as sulfate or organic matter can turn the treated soils unfavorable at times even worser than the unstabilized ones. Provision of nano-silica not only improves soil packing but also accelerates the pozzolanic reaction. The degree of stabilization is controlled by several factors such as additive type, additive content, soil type, soil mineralogy, curing period, curing temperature, delay in compaction, pH of soil matrix, and molding water content, including presence of nano-silica, organic matter and sulfate compounds. It is observed that the stabilization process primarily involves hydration, cation exchange, flocculation and pozzolanic reactions. In this paper, suitability of such additives under various conditions and their mechanisms are reviewed in detail. This can be achieved through chemical stabilization using additives such as lime, cement and fly ash.

It is, therefore, necessary to adequately improve the performance of such soils that they can favorably fulfil the post-construction stability requirements. Volume instability of expansive soils due to moisture fluctuations is often disastrous, causing severe damages and distortions in the supported structures.

Air doc belle fourche sd