Durability Assessment of Self-Compacting Sand Concrete Incorporating Windshield Glass Aggregate Under Extreme Environmental Conditions: High Temperature and Freeze–Thaw Cycling

This study evaluates the durability of Self-Compacting Sand Concrete (SCSC) incorporating Windshield Glass Aggregate (WGA) as a sustainable replacement for natural sand, utilizing Blast Furnace Slag (BFS) as a constant filler component. Eleven mixtures were investigated: a control mix and ten variants with WGA substitution levels ranging from 10% to 100% in 10% increments. The specimens were exposed to elevated temperatures of 200–800 °C and to 240 freeze–thaw cycles between −18 °C and +9 °C. Under heating, mass loss increased with temperature, but WGA-rich mixtures generally showed lower mass loss and higher residual mechanical performance than the control. At 400 °C, WGA100 reached about 96 MPa in compressive strength and 15 MPa in flexural strength, corresponding to residual values of approximately 110.34% and 166.7%, respectively. After freeze–thaw cycling, all mixtures showed limited surface deterioration and mass loss below 1%, decreasing from about 0.76% for the control mixture to about 0.05% for WGA100. The improved durability is mainly attributed to the physical effect of WGA replacement and the baseline matrix refinement associated with BFS.