Investigation of Moisture Content-Induced Variations in Resilient Modulus of Unbound Aggregates Through Suction Stress Concept

Even though the influence of moisture content on unbound aggregates’ resilient modulus has been well recognized, accurate prediction of this influence remains a challenge. With prediction models incorporating matric suction, great improvement has been achieved in understanding and modeling moisture-dependent resilient modulus. Nevertheless, the requirement of soil-water characteristic curve (SWCC) in these models may present an obstacle for widespread adoption of these models due to very time consuming process of SWCC determination. On the basis of suction stress concept, which is lumped macroscopic effect of various interparticle physiochemical forces, a prediction model for resilient modulus is proposed. The feasibility of the suction stress based model has been confirmed by laboratory testing results on a Louisiana unbound aggregate (Mexican limestone) as well as literature data for a California crushed aggregate. The procedure of how to implement the suction stress-based prediction model is illustrated in this study, which involves the determination of suction stress characteristic curve (SSCC) by conducting conventional monotonic unconsolidated undrained triaxial tests and obtaining resilient modulus from repeated load triaxial tests. As SSCC bridges moisture content and suction stress, the proposed model avoids the need of SWCC determination. Therefore, the proposed model provides a theoretically rigorous, yet practically simple means to consider the variation of resilient modulus due to seasonal moisture content fluctuations, which can readily be implemented by most state highway agencies.