Eco plaster mortars with addition of waste for high hardness coatings

•It is feasible to incorporate ceramic waste along with XPS waste in a gypsum matrix.•These compounds improve the superficial hardness of the gypsum reference.•The addition of XPS in a gypsum matrix with ceramic waste improves the water absorption and the type of breakage adherence.•Compounds coming closest to the mechanical resistance of the reference sample are those adding 1%XPS. This paper studies the physical and mechanical behavior of a lightened eco-plaster mortar, manufactured with aggregates from ceramic and extruded polystyrene (XPS) wastes. The aim of incorporating these fillers in the gypsum matrix is to reduce the amount of raw material used for its manufacture and improve the characteristics of traditional gypsums – without additions – to be applied in coatings needing higher superficial hardness values and even better water capillarity absorption. To do this, several gypsum samples were prepared using different percentages of waste based on the weight of gypsum (1%, 2% and 3% of XPS and 25% and 50% of ceramic) and also reference samples (with no additions). These samples were tested in the laboratory and the following physical and mechanical characteristics were determined: dry density, flexural strength, compressive strength, water capillarity absorption, bonding strength and superficial hardness. A comparative analysis evidenced that it is viable preparing gypsum plaster mortars with addition of XPS and ceramic waste. These compounds reduce the water absorption by capillarity and increase the superficial hardness compared with reference gypsum.