Characterisation and influence of the content of waste foundry sand on rendering mortars

Abstract Waste foundry sand is a waste product generated by the foundry industry that has potential applications in construction. The aim of this study was to characterise and evaluate the influence of phenolic foundry waste sand content on rendering workable mortars. Mortars were produced (using Portland cement and lime) replacing natural sand at 0%, 10%, 30% and 100% (in volume) with waste foundry sand. Corrosivity tests, reactivity tests, leaching extract assessments and solubilized extraction of solid waste were performed on the waste foundry sand and the waste of the studied mortars. The results demonstrated that the waste foundry sand had an influence on the properties of the mortars in fresh state (mainly for the mortar with 100% waste foundry sand, which required the use of a larger amount of water to obtain the same consistence) and in the hardened state (decrease in strength, mass density and modulus of elasticity). We observed that, comparing with the waste foundry sand itself, the mortar with the waste foundry sand had lower concentrations of iron, fluoride and sodium when, but higher concentrations of aluminium, chromium and total phenolics. The waste studied was classified as non-dangerous - Class II A - non-inert according to NBR 10004 (ABNT, 2004).