The effect of treated flue gas desulfurization (FGD) sludge addition on the properties of non-stoichiometric cordierite

This study examines the incorporation of treated Flue Gas Desulphurization (FGD) by-products from the glass industry in Malaysia into non-stoichiometric cordierite compositions, focusing on its effects on the physical, mechanical, and microstructural properties. New ceramic samples were developed using a blend of kaolin, silica, talc, and treated FGD sludge. The results indicate that increasing the amount of treated FGD sludge leads to desirable properties such as a low thermal coefficient of expansion (2.62 – 3.64 x 10-6/ ℃), reduced density, and decreased average flexural strength (34.43 – 54.69 MPa), along with an increase in average porosity (17.04 - 31.90 %). Notably, ceramics that were treated with 3 wt% FGD sludge crystallized α-cordierite at a lower sintering temperature (1250 ℃), whereas traditional solid-state reaction methods need higher temperatures (>1350 ℃) to make α-cordierite. Overall, replacing feldspar with treated FGD sludge in non-stoichiometric cordierite formulations presents a sustainable strategy for recycling industrial waste and reducing the need for natural resources. The resulting materials exhibit characteristics suitable for lightweight construction applications, such as commercial bricks, due to their light weight, adequate flexural strength, and appropriate porosity.