Enhancing freeze-thaw and sulfate resistance of expanded perlite-based alkali-activated lightweight composites with waste tire aggregates and brick powder
摘要
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 °C and 80 °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 °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 °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 °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 °C, while all suffered ≥ 90% loss at 350 °C. Strong inverse correlations were observed between weight loss and compressive strength across durability tests (R² ≥ 0.90). Thermal conductivity ranged from 0.432 to 0.527 W/m·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.