Development of Lightweight Alkali-Activated Foams from Roof Tile and Marble Wastes: Pore Structure Evolution and Thermal Performance Optimization


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Ekiz Barış K.

Sustainability, cilt.18, sa.14, ss.1-34, 2026 (Hakemli Dergi)

Özet

The growing demand for sustainable construction materials has encouraged the development of waste-based alkali-activated foams (AAFs) with enhanced thermal performance. This study investigates the use of roof tile waste (RTW) and marble waste (MW) for producing lightweight AAFs and evaluates the influence of aluminum (Al) powder on material performance. The novelty of this study lies in combining binder optimization, systematic evaluation of Al-induced pore evolution, and quantitative sustainability assessment within a single experimental framework. RTW was partially replaced with MW to optimize the binder, followed by the incorporation of Al powder (0–0.20 wt%) as a foaming agent. In an alkaline medium, metallic Al released H2 gas, generating the porous structure of the AAFs. Physical, mechanical, thermal, microstructural, and material-based environmental properties were evaluated. In the binder optimization stage, 30% MW increased the compressive strength from 5.57 to 15.50 MPa. During AAF production, increasing Al content reduced dry-state thermal conductivity from 0.99 to 0.09 W/m·K, although excessive Al promoted pore coalescence and strength loss. The optimum 70RTW:30MW:0.15Al mixture exhibited a unit weight of 0.56 g/cm3, a dry-state thermal conductivity of 0.15 W/m·K, a compressive strength of 3.12 MPa, 79.9% waste incorporation, and 65.9% lower material-based embodied carbon than an ordinary Portland cement (OPC)-based reference binder, demonstrating its suitability for lightweight non-loadbearing wall applications.