Durability, Strength, and Stiffness of Dispersive Clay-Lime Blends

Dispersive clays undergo deflocculation in the presence of relatively pure still water to form colloidal suspensions and as such are highly susceptible to erosion and piping. Lime treatment is one of the most practical methods to improve such undesirable characteristics of dispersive clays, as well as improve their mechanical properties. The present research aims to quantify the influence of amounts of hydrated lime, compacted dry unit weight, and curing time in the assessment of transformation to a nondispersive state by the lime treatment, as well as improving durability, strength, and stiffness properties of clay-lime mixtures. This manuscript advances understanding of the parameters controlling strength and stiffness of compacted lime-treated dispersive clay soil by quantifying the influence of porosity/lime index initial shear modulus (Go) and unconfined compressive (qu) and split tensile (qt) strengths. A single qt/qu relationship equal to 0.136 was found, being independent of the porosity/lime index and curing time. Unique relationships between Go/qu and adjusted porosity/lime index of the dispersive clay soil-lime mixtures is shown for each curing time studied, linking initial stiffness and strength. Finally, while 2% of lime is enough to turn the dispersive clay studied herein into a nondispersive soil, it is quite clear that the minimum amount of lime for clay stabilization is 3%, at any dry unit weight, and this amount of lime definitely enhances both strength and stiffness. However, regarding durability, 5% is the amount of lime needed for guaranteeing endurance of the stabilized dispersive clay-lime blends. (C) 2016 American Society of Civil Engineers.