A comparative evaluation of various additives used in the stabilization of expansive soils

This paper investigates the effectiveness of using cement by-pass dust, copper slag, granulated blast furnace slag, and slag-cement in reducing the swelling potential and plasticity of expansive soils. The soil used in this study was brought from Al-Khod (a town located in Northern Oman) where structural damage was observed. The first stage of the experimental program dealt with the determination of the chemical, mineralogical, and geotechnical characteristics of the untreated soil. The soil was then mixed with the stabilizers at 3, 6, and 9% of the dry weight of the soil. The treated samples were subjected to liquid limit, plastic limit, swell percent, and swell pressure tests. Furthermore, the cation exchange capacity, exchangeable cations (Na⁺, Ca⁺⁺, Mg⁺⁺, and K⁺), and pH of the treated samples were also measured. The study showed that copper slag caused a significant increase in the swelling potential of the treated samples. Other stabilizers reduced the swelling potential and plasticity at varying degrees. The study further indicated that cation exchange capacity and the amount of sodium and calcium cations are good indicators of the effectiveness of chemical stabilizers used in soil stabilization.