Constitutive model of geopolymer concrete with non-sintered aggregates under freeze-thaw cycles considering different sand ratios

Abstract

To investigate the influence of sand ratio on the axial compressive behavior of geopolymer concrete incorporating non-sintered aggregates under freeze-thaw cycles, nine prismatic specimens with sand ratios of 0.45, 0.55, and 0.65 were prepared. Rapid freeze-thaw tests and uniaxial compression tests were conducted to obtain the complete stress-strain curves. The results indicate that, after 25, 50, and 75 freeze-thaw cycles, crack propagation accelerates significantly during monotonic loading, and the failure mode becomes increasingly brittle and fragmented. With the increase in freeze-thaw cycles, the axial compressive strength and elastic modulus decrease markedly, whereas the peak strain and ultimate strain increase. Based on the Guo Zhenhai model, regression analysis was performed to modify the ascending parameter a and descending parameter b. A full stress-strain constitutive model for geopolymer concrete with non-sintered aggregates was established. The predicted results agree well with the experimental data, demonstrating the accuracy and applicability of the proposed model.