Behavior of Stabilized Subgrade Soils under Indirect Tension and Flexure

Abstract

A laboratory study was undertaken to evaluate the influence of three cementitious additives on the indirect tensile and fatigue behavior of two subgrade soils. Hydrated lime (or lime), class C fly ash (CFA), and cement kiln dust (CKD) were used as additives. Cylindrical specimens were prepared, cured for 28 days, and subjected to different stress sequences in indirect tension to study the resilient modulus. Moreover, stabilized beam specimens were subjected to repeated cycles of reloading-unloading after 28 days of curing in a four-point beam fatigue apparatus for evaluating fatigue life and flexural stiffness. These properties were compared with those of the control soil specimens in order to determine the extent of enhancement. Results indicate that all three additives improved the indirect tensile and fatigue properties; however, the degree of improvement varied with the type of additive and soil. The properties evaluated under indirect tension mode projected 10 percent CKD with highest improvement after 28 days of curing, while evaluation under flexure mode showed 6 percent lime providing maximum enhancements in fatigue life. The properties evaluated in this study are expected to provide a better understanding of the performance of a stabilized subgrade layer in a mechanistic sense.