Field-derived energy-based performance and moisture resilience of cemented base materials in flexible pavements under monsoon exposure

Seasonal moisture variations due to monsoon pose a significant challenge to the structural performance of flexible pavements. This field study evaluates the influence of monsoon on flexible pavement test sections constructed with innovative cemented base layers, namely steel slag – fly ash – lime (SFL), copper slag – fly ash – lime (CFL) and copper slag – class C fly ash (CCF) mixes, in comparison with a conventional pavement section with wet mix macadam (WMM) base. An advanced analytical framework was adopted to derive dissipated energy and phase angle from falling weight deflectometer (FWD) load–deflection time history data, enabling a comprehensive assessment of pavement response before, during, and after monsoon. Pavement sections with thicker cemented bases (250 mm), particularly SFL, exhibited superior resistance to monsoon-induced deterioration, with only an 8% increase in peak deflection compared to substantially higher increases in thinner cemented layers and the control section. Cemented base layers demonstrated rapid post-monsoon recovery, marginal reductions in composite moduli, and narrower hysteresis loops, confirming reduced susceptibility to traffic and seasonal damage. In-situ moisture monitoring further revealed that monsoon primarily affects subbase and subgrade layers, while cemented bases effectively limit moisture ingress. The findings of this field study establish the efficacy of innovative cemented base materials in enhancing monsoon resilience and overall structural stability of flexible pavements.