Durability mechanics of quicklime grout in environmental cycles for earthen site repair

This study investigates the durability degradation and damage evolution of a novel quicklime-based composite grout under coupled environmental and mechanical attacks. The grout, formulated as an organic–inorganic composite with a binder (polyvinyl alcohol or glutinous rice paste) and a quicklime–fly ash–soil matrix (3:2:5 mass ratio), was subjected to five accelerated ageing regimes: dry–wet, freeze–thaw, sulfate-wet, alkali-wet and ultraviolet cycles. Its mechanical response was then characterised through triaxial compression tests under varying confining pressures. Results demonstrated a systematic transition from ductile to brittle failure with increasing environmental cycles. While different exposures differentially altered the key mechanical indices and energy parameters, all conditions led to progressive damage accumulation. The underlying mechanisms, governed by the environmental-specific degradation of the binder–matrix networks, were elucidated through a newly developed constitutive model and energy evolution analysis. This work provides fundamental insights into the long-term performance evolution of lime-based repair materials. The constitutive model and energy-based framework establish a practical methodology for durability assessment and prediction of similar composite materials in civil engineering applications.