Effect of the waste ornamental rocks on the hydration and life cycle of Portland cement composites

Abstract

The production (extraction, cutting and polishing) of ornamental rocks generates a high volume of waste (abrasive slurry) which, when dry, generates a fine powder. The main impacts generated by the inadequate disposal of these residues are the contamination of the soil and the water table, alteration of the biological chain of living beings and siltation of rivers. Few studies analyze the influence of mud heterogeneity on the hydration of cementitious composites. In this context, this work aimed to evaluate the effect of the characteristics (chemical, physical and mineral) of waste from wet processing in ornamental rock plants (marble, granite, slate, among others) of different origins on the hydration process, performance and life cycle of composite with 20% replacement of Portland cement. Heterogeneity was evaluated by chemical composition, mineralogical and physical characteristics of the waste. The reactivity of the residue was determined in the Chapelle Modified test, Thermogravimetric analysis, and expansion test by Le Chatelier needles. The evolution of hydration was studied in pastes by evaluating the setting time and using the differential scanning calorimetry test. The mortars were characterized for consistency, porosity, and compressive strength. The results indicated that the residues show considerable heterogeneity. However, this does not influence the analyzed properties of the cementitious compounds. The high reduction in axial compressive strength indicates the use of these residues in lower contents or indication of this cement with this residue for non-structural purposes. It was concluded that the filer feat accelerated the hydration reactions in a similar way to the cement removed from the mixture.