Matriz cimentícia composta por pó de rocha para tratamento de efluentes

Abstract

The construction sector is one of the largest consumers of natural resources. Cementitious materials, such as mortars and concrete, are widely used in buildings. The production of these materials requires an intensive demand for natural inputs, which, in turn, generates environmental impacts during their extraction. To mitigate these impacts, the use of waste materials has gained prominence due to their properties and their reintegration into the construction cycle. A byproduct of basalt rock mining, known as “rock powder,” is recognized for its physical and chemical properties compatible with cementitious composites. The literature reports its use as an additive in concrete or as a partial replacement for cement or sand. However, a significant but underexplored characteristic of this byproduct is its potential as a photocatalytic semiconductor. Heterogeneous photocatalysis is one of the processes that can be applied to wastewater treatment. The interaction of a semiconductor with light leads to the formation of highly reactive radical species, which degrade pollutant compounds. In this context, this study developed cementitious composites using basalt rock powder as a substitute for natural sand, aiming at wastewater treatment applications. Mortar plates were prepared with partial sand replacement by rock powder at 25%, 50%, 75%, and 100%. The photocatalytic potential of the material was tested using mortar plates immersed in 500 mL of methylene blue dye solution (10 mg/L concentration) under UV radiation for different periods. The mortars with basalt rock powder exhibited up to 48% higher photocatalytic efficiency than the control mortar. Additionally, the rock powder enabled dye degradation of up to 85% under UV light photocatalysis. Therefore, the use of basalt rock powder is a viable alternative for replacing aggregates in cementitious composites, as it not only reduces natural sand extraction but also repurposes mining waste, contributing to the sector's sustainability and enabling cementitious composites with photocatalytic capabilities for wastewater treatment.