Performance of Sand-Treated Clay Subgrade Supporting a Low-Volume Flexible Pavement

Abstract

Low-volume roads constitute a major portion of the world's transportation infrastructure and hence require an economical and effective pavement design. When constructed on unstable and soft subgrades, these roads are susceptible to premature pavement failures and require subgrade stabilization. The presented research focuses on mechanical stabilization of soft clay with graded sand that has been adopted as a base course for pavements. For this study, a local soft clayey soil from Dallas was mixed with various fractions of a graded sandy soil, and the stiffness behavior of the compounded material was studied. The soil mixtures were then studied for their basic soil characterization, including standard Proctor compaction studies. Statically compressed soil specimens were prepared and then evaluated for their unconfined compressive strength and resilient moduli. Resilient moduli results were used in the design of low-volume roads, both with aggregate base and with no aggregate base. Results show that the variation of sand content in soft soil considerably affects the strength and stiffness properties of the subgrade. The effects of improved subgrade performance on the aggregate base and surface layers of the low-volume pavement are highlighted.