COMPACTED ADOBES FROM GRAVEL AND SAND WASH MUDS OF AN AGGREGATES PLANT AS WASTES VALORIZATION STRATEGY

Abstract

Fine waste management from quarry has been commonly the final disposal in mining tailings and as refilling material for landscape recovery in areas already exploited. However, different uses of these wastes have been studied, highlighting the earth constructions because a new economic benefit is generated and the environmental impact is reduced. Moreover, compared to cement constructions, the earth constructions are environmentally friendly and represent an energy saving, due to their low emission of CO2 by low or no-cement content in their manufacture in contrast to good physical and mechanical properties obtained. So, in this work, the use of wastes muds from an aggregates plant (as result of crushing and washing process) were evaluated as a circular economy strategy. Raw materials were chemical, mineralogical and physically characterized and were employed in the elaboration of cubic specimens of un-calcined material, which they were hydraulically compacted in metal molds at mixtures of wastes muds, commercial gray cement and washed fine sand. The cubic specimen’s performance was evaluated by Simple Compressive Strength (SCS) and water absorption test. In the best of configurations, an increase in SCS of 221.3% (reaching 8 MPa) on samples of 20% cement with respect to samples of only waste was found and, in turn, an increase of 517.3% (reaching 15 MPa) when these were cured in water was also found. Thus, wastes mixed with small amounts of cement are promising in the Manufacture of Compacted Adobes (MCA), particularly as masonry or structural elements made of un-calcined wastes.