An Assessment of Soil Parameters Governing Soil Strength Increases with Chemical Additives

This study examined the relationship between soil physico-chemical parameters and unconfined strength in various fine-grained soils when mixed with chemical additives. To be considered effective, the soil-additive mixture must exhibit a strength increase of at least 345 kPa (50 psi). The research focused on AASHTO Soil Group Classifications falling under the fine-grained soil category (A-4 to A-7). Additive amounts are given for Fly Ash (FA), Cement Kiln Dust (CKD), and Lime (hydrated and quick lime). The results of this study suggest that the surface area is perhaps the most important factor in determining if a chemical additive will be effective for stabilization. Out of the eight tested soils, the seven soils with surface areas lower than 150 m²/g reached the 345 kPa strength gain with the different additives. However, the one soil with a surface area higher than 150 m²/g never reached the strength gain with any of the additives used at any of the tested percentages.