Evaluation of Strength, Resilient Moduli, Swell, and Shrinkage Characteristics of Four Chemically Treated Sulfate Soils from North Texas

Expansive soils with sulfate levels typically greater than 2,000 ppm are prone to sulfate heaving. Heaving in such soils cannot be effectively reduced using conventional stabilization techniques (i.e., calcium or lime based stabilizers). This paper presents research findings from stabilization studies conducted on an expansive soil from south Arlington, Texas with sulfates levels around 5,000 ppm. Four different stabilizers, namely; class F fly ash with type V cement, type V sulfate resistant cement, ground granulated blast furnace slag (GGBFS), and combined lime-fiber treatments were used to reduce the expansive nature associated with sulfate heaving and to enhance strength properties. Experiments were designed to study the effects of stabilization methods on compaction moisture content - dry unit weight relationships, Atterberg limits, linear shrinkage, free swell strain, resilient moduli and unconfined compressive strength properties. The study shows type V sulfate resistant cement provided the most effective treatment, followed by class F fly ash with type V cement treatment, GGBFS and finally the lime-fiber treatment. A simple linear ranking analysis was used to rank the stabilizers in this study based on the soil property enhancements by different stabilizer treatments.