Uniaxial cyclic compression behaviour and constitutive model of strain-hardening cementitious composites (SHCC) with limestone and calcined clay

Limestone–calcined clay strain hardening cementitious composites (LCC–SHCCs) have emerged as a sustainable alternative to conventional SHCCs, offering reduced CO₂ emissions while maintaining high ductility. These advantages make LCC-SHCC suitable for the infrastructure subjected to severe cyclic loads, such as earthquakes. However, limited experimental data are available to describe the cyclic behaviour, and no constitutive model has been established for LCC-SHCC. This study focused on the mechanical response of LCC-SHCC with varying water-to-binder ratios and LCC contents under uniaxial cyclic compression. Axial, circumferential, and volumetric stress–strain relationships were analysed and the failure mode was recorded. The results indicated that all LCC–SHCC specimens exhibited ductile shear failure without visible spalling. The stress–strain curve trends were unaffected by LCC content (30 %–60 % of the binder), while the water–to–binder ratio exhibited a significant influence. Based on characteristic points of the axial stress–strain curve, the relationships between residual strain and unloading strain/reloading strain were established and a stiffness degradation index was calculated for each cycle. Finally, piecewise constitutive model containing the unloading and the reloading phases was proposed a for LCC–SHCCs under low–cycle loading, which accurately predicts the unloading path, reloading path, and residual strain evolution. Without compromising the cyclic mechanical performance, the embodied energy and CO₂ emissions of the mixtures decrease progressively with increasing LCC content.