Performance of soil stabilization agents

TLDR: In this paper, the performance of lime, cement, Class C fly ash, portland cement and Permazyme 11-X were compared with a wide range of soils.

Abstract: Poor subgrade soil conditions can result in inadequate pavement support and reduce pavement life. Soils may be improved through the addition of chemical or cementitious additives. Such chemical additives range from waste products to manufactured materials and include lime, Class C fly ash, portland cement and proprietary chemical stabilizers. These additives can be used with a variety of soils to help improve their native engineering properties. This report contains a summary of the performance of lime, cement, Class C fly ash, and Permazyme 11-X used with a wide range of soils. Each of the chemical additives tested is designed to combine with the soil to improve the texture, increase strength and reduce swell characteristics. These products were combined with a total of eight different soils with classifications of CH, CL, ML, SM, and SP. Durability testing procedures included freeze-thaw, wet-dry, and leach testing. Atterberg limits and strength tests were also conducted before and after selected durability tests. Changes in pH were monitored during leaching. Relative values of soil stiffness were also tracked over a 28-day curing period using the soil stiffness gauge. Lime and cement stabilized soils showed the most improvement in soil performance for multiple soils, with fly ash treated soils showing substantial improvement. The results showed that for many soils more than one stabilization option may be effective for the construction of durable subgrades. The enzymatic stabilizer did not perform as well as the other stabilization alternatives. It is recommended, based on the results of this research, that some testing of the contribution of proposed stabilization agents be conducted prior to construction. For pavement designs that expect a relatively limited strength contribution from the soil, the primary anticipated benefit of stabilization is generally the control of volume change.