Enhancing freeze-thaw and sulfate resistance of expanded perlite-based alkali-activated lightweight composites with waste tire aggregates and brick powder

The utilization of industrial and construction wastes in binder and aggregate systems offers an effective pathway toward sustainable and eco-efficient construction materials. This study examines the mechanical and durability performance of expanded perlite-based alkali-activated lightweight composites (AALCs) incorporating waste tire aggregate (WTA) as a partial or full replacement for expanded perlite (EP) and brick powder (BP) as a supplementary binder with ground granulated blast furnace slag (GBFS). Eight mixtures were prepared with WTA at 0-100% (by volume) and BP at 0-10% (by mass), activated with 12 M NaOH and sodium silicate (SiO2/Na2O = 2.0). Specimens were thermally cured at 40 degrees C and 80 degrees C for 8 h, then tested for compressive and flexural strength, oven-dry density, thermal conductivity, sorptivity, freeze-thaw resistance, high-temperature stability (up to 350 degrees C), and 90-day sulfate resistance in 5% MgSO4. The highest compressive strength (28.82 MPa) was obtained in the GBFS-only mix cured at 80 degrees C. Increasing WTA reduced strength but improved freeze-thaw and thermal performance; full EP replacement (100RB0) yielded the lowest strength (10.15 MPa at 40 degrees C) yet showed excellent freeze-thaw durability with only 3.84% loss. Incorporation of 10% BP enhanced sulfate resistance, with 25RB10 showing 13.63% strength loss versus 29.02% in the unmodified mix. Under thermal exposure, BP mixes retained up to 68% of strength at 250 degrees C, while all suffered >= 90% loss at 350 degrees C. Strong inverse correlations were observed between weight loss and compressive strength across durability tests (R-2 >= 0.90). Thermal conductivity ranged from 0.432 to 0.527 W/m<middle dot>K, decreasing with WTA content. These findings confirm that optimized use of WTA and BP produces lightweight, durable, and eco-efficient AALCs, supporting circular economy goals through waste valorization.