Effect of Stress–Strength Ratio on Creep Property of Sodium Silicate–Based Alkali-Activated Slag Concrete

Alkali-activated materials have attracted increasing interest owing to their excellent properties and environmental protection. However, there have been few studies on their creep properties. The aim of this article is to investigate the effect of the stress−strength ratio on the creep property of sodium silicate−based alkali-activated slag (AAS) concrete. For this reason, five groups of AAS concrete with different stress−strength ratios (0.15, 0.3, 0.45, 0.6, and 0.75) were tested. The results indicate that the creep of AAS concrete has a convergent nonlinear stage and a non-convergent stage but not an obvious linear stage. The AAS concrete basically has a consistent creep coefficient and diverse specific creep under a stress−strength ratio of 0.15−0.6. The elasticity modulus of AAS is much smaller than that of ordinary Portland cement (OPC) concrete, which is the reason for the greater creep compared to that in OPC concrete, and the inaccuracy of the model prediction. By applying the actual elastic modulus, the models can predict the specific creep and stress-dependent strain of AAS concrete with a 0.3 stress−strength ratio, except for the B3 model. The secant modulus of AAS concrete decreases linearly with an increase in the stress−strength ratio. Finally, we propose an improved creep model for AAS concrete with a wide stress−strength ratio based on the GL2000 model.