Fracture properties of concrete under freeze–thaw cycles and sulfate attack

Abstract

• The fracture properties of concrete exposed to freeze–thaw cycles in different sulfate solutions were investigated. • The visual change, weight loss, relative dynamic elastic modulus, compressive strength and fracture parameters of concrete were studied. • The evolutions of the fracture process zone and damage scale of the specimens were analyzed. The fracture properties of concrete exposed to freeze–thaw (F-T) cycles in different sulfate solutions were investigated using pre-notched three-point bending beams. 5 % Na 2 S0 4 , 5 % MgS0 4 (by mass) and water, i.e. three exposure conditions were considered. The visual change, weight loss, relative dynamic elastic modulus, compressive strength and fracture parameters of concrete were measured at every 25F-T cycles. The evolutions of the fracture process zone (FPZ) and damage scale of the specimens were studied. Results indicate that (1) before 100F-T cycles, the specimens in water suffer severer damage than those in sulfate solutions, and the deterioration degree of the specimens in 5 % Na 2 S0 4 is the greatest after 200F-T cycles. (2) With increasing the F-T cycles, the obtained double- K fracture parameters, microcracking zone length and aggregate occlusion zone decrease linearly. Morever, the maximum FPZ length basically decreases, and a small increase tendency is observed at 125 and 150F-T cycles due to the significant increase in the deformation capacity of the specimens.