Axial compressive behavior of fiber-reinforced alkali-activated slag concrete with seawater and sea-sand: mechanical properties and constitutive modeling

alkali-activated slag concrete with seawater and sea-sand (AAS-SSC) is an innovative type of green building material that utilizes seawater and sea sand instead of freshwater and river sand. Despite the broad application prospects for AAS-SSC, no relevant research on the axial compressive properties of AAS-SSC has been conducted. This study investigates the effects of fiber type (basalt fiber, polypropylene fiber) and content (0%∼1%) on the failure modes, elastic modulus, axial compressive strength, and stress-strain relationship of AAS-SSC under axial compressive loads. Additionally, it evaluates the applicability of existing elastic modulus calculation formulas and concrete constitutive models for AAS-SSC. The results indicate that in AAS-SSC, shear failure is the dominant mode, though the inclusion of fibers effectively reduces crack width. When reinforced with basalt fibers, AAS-SSC demonstrates a notable 17.2% enhancement in peak strain. Concurrently, the elastic modulus of AAS-SSC is found to be 48% lower than that of ordinary concrete, a critical mechanical property requiring attention in structural design. To characterize its mechanical behavior, a constitutive model capable of predicting the stress-strain relationship of AAS-SSC is proposed. These findings contribute to the promotion of AAS-SSC in structural engineering and virtual simulation.