Fire-resistant panels composed only of combustion by-products

The reuse of two wastes from coal combustion in the manufacture of panels to be used as building materials or in the protection of metal structures against fire was analysed in this study. The panels were composed of 100% coal combustion by-products. The wastes used were fly ashes and flue gas desulfurisation gypsum from the combustion of coal in a Spanish power plant. The gypsum was previously calcined for 6 h at 150°C. Different mixtures of gypsum and fly ash were tested. The mixtures were kneaded with water until a homogeneous paste was achieved, with which moulds were filled. After 28 d at ambient temperature, the panels were subjected to different physical (density, pH and humidity), mechanical (compressive strength and surface hardness) and fire-resistance tests. Moreover, leaching tests were applied to the fly ash and gypsum. The results obtained were evaluated with the requirements established in some European standards for commercial gypsum products. The fire resistance of the panels under study was found to be higher than that of commercial gypsum and they also showed good mechanical properties.