DURABILITY PROPERTIES OF RECYCLED CONCRETE WITH LITHIUM SLAG UNDER FREEZE-THAW CYCLES

Abstract

A water freeze-thaw cycle and sulfate freeze-thaw coupling cycle were explored experimentally to evaluate the durability of recycled concrete with lithium slag (LS). The damage-deterioration law was studied from the aspects of mass-change rate, relative dynamic modulus of elasticity, and cube’s compressive strength. Based on the relative dynamic modulus of elasticity, the damage-degree equation of the concrete was fitted, and a mechanical-attenuation model related to this parameter and the cube’s compressive strength was established and verified. The damage mechanism under the action of the sulfate freeze-thaw cycle was revealed through scanning electron microscopy (SEM). The combination of recycled coarse aggregate (RCA) and LS was beneficial to the anti-deterioration ability of the concrete. During the cycle experiments, the mass and relative dynamic modulus of elasticity increased initially and then decreased, while the cube’s compressive strength declined continually. The concrete with a 30 % RCA substitution rate and 20 % LS exhibited the optimal comprehensive durability, and specimens with excessive LS showed more susceptibility to sulfate erosion. The residual compressive strength of concrete structures can be evaluated by measuring the relative dynamic modulus of elasticity as the two parameters are ideally correlated.