Impact of Sulfate Contamination on Swelling Behavior of Lime-Stabilized Clays

Abstract Lime treatment is commonly resorted to improve the geotechnical properties of expansive clays and soft clays. Lime treatment, however, has a detrimental effect on soil behavior if adequate amounts of sulfate are present in soil. Sulfate induced heave of soils stabilized with calcium-based stabilizers occurs due to the presence of primary and secondary sources of sulfate in soils. The occurrence of native sulfate in natural soils constitutes primary sulfate source. Sulfates present in construction wastes, industrial wastes, and spilled chemicals constitute the secondary sulfate source. The present study performs laboratory experiments to examine the impact of sulfate contamination from spillage of sulfate rich chemicals on the heave characteristics of lime-stabilized expansive clays. The objective was realized by infiltrating laboratory prepared sodium sulfate solutions (sulfate concentrations ranged from 13 500 ppm to 27 000 ppm) on the heave characteristics of lime-stabilized specimens that were practically free of natural sulfate (sulfate content of natural soil = 0.05 %). Experimental results illustrated that lime-stabilized expansive clays experiencing sulfate contamination are susceptible to heave from sulfate attack. Mass balance reactions were performed to gain insight into mechanisms of sulfate interactions with lime-stabilized specimens.