Impact of test setup, material conditions and stress history on non-linear resilient behaviour of cement-treated aggregates

Resilient modulus (Mr) of cement-treated aggregates (CTA) is a key parameter for designing pavement, yet its measurement is complicated by stress nonlinearity and testing setup. This study investigates the dynamic triaxial resilient modulus of CTA using both top- and side-mounted LVDT setups. By analyzing twelve CTA specimens across various curing times, binder types, compaction methods, and stress histories, the research identifies the Mr evolution from paving through service life. Results indicate that the side-mounted LVDT setup aligns better with the field observations, and Mr magnitude is primarily driven by stress history complexity, compaction energy, and cementation efficiency. Under short-curing age, low-binder or static-compaction conditions, CTA shows small resilient modulus value and Type I stress-dependence, with modulus increasing with bulk stress but decreasing with octahedral shear stress. In contrast, high-compaction, long-age or well-serviced specimens display significantly higher modulus values with Type II stress-dependence, where modulus changes only with maximum axial stress. The divergence in the two models stems from variations in particle packing density. The experimental results suggest that CTB undergoes four distinct stages during service, namely, Type I stress-dependence, Type II stress-dependence, elastic and fatigue phases, with the modulus first increasing and then decreasing over time.