Lightweight alkali activated composites by direct foaming based on ceramic tile waste and fly ash

This study aims at investigating for the first time if ceramic waste coming from the rectifying process of porcelain stoneware tiles are suitable to prepare alkali activated lightweight composites. After successfully designing alkali activated materials based on ceramic waste, different foaming agents were added alone or in combination with sodium dodecyl sulfate acting as pore stabilizing agent. Addition of expanded perlite as lightweight constituent was also tested. Different properties, such as geometric density, water absorption, porosity and pore size distribution by mercury intrusion porosimetry and SEM observations, and thermal conductivity, were measured in view of their potential future applications. The results highlight that combining ceramic tile waste as raw materials, hydrogen peroxide as foaming agent, sodium dodecyl sulfate as pore stabilizing agent and expanded perlite allow the preparation of optimized lightweight composites with a density of 0.75 g/cm3, a water absorption greater than 70 % and a thermal conductivity of 0.26 W/mK.