Agate waste valorization in mortars and concretes: life cycle assessment

ABSTRACT The application of residues from agate beneficiation process (agate powder) in mortars and concretes based on Portland cement is technically viable considering materials mechanical properties and durability. However, there is a lack of studies that assess the environmental profile of the produced materials. This paper aims to evaluate the potential environmental impacts associated to the life cycle of mortars and concretes produced with the application of agate powder in substitution of Portland cement and fine aggregate, respectively. To that, experimental designs defined in previous studies were considered, to perform a cradle to gate analysis, where the following impacts were evaluated, according to CML-IA method: climate change, soil and water acidification, eutrophication, ozone layer depletion, and resources depletion (fossil and non-fossil). Results show up to 30% reduction of potential impacts, for the application of the residue in substitution to Portland cement in mortars. Less expressive reductions are observed for the use of the residue in substitution of the fine aggregate; however, gains on mechanical strength justify the application of the residue in specific cases. Since all the assessed impacts are closely related to cement consumption, the application of the residue to replace cement is considered the most environmentally viable alternative, for the evaluated cases. The participation of the transport processes in all impact categories validates the application of materials locally produced/extracted. Finally, future studies shall consider the performance of the produced materials, in comparison to the reference ones.