Análise da viabilidade do uso de resíduos de construção e demolição para a geração de blocos reciclados

Abstract

The Northeast is the third largest region in Brazil in terms of construction and demolition waste generation, according to ABRELPE (2021). With increasing urbanization, there is a growing trend in waste generation, which has led the United Nations to highlight solid waste as one of the main current problems. Therefore, finding an adequate disposal for these wastes strengthens environmental sustainability and the development of sustainable cities. In this context, a sustainable opportunity for disposal of Construction and Demolition Wastes (CDW) arises, such as the production of new construction materials, for example, recycled blocks, since blocks have the potential to reduce construction costs by up to 30%, as per Paes (2010). This research evaluates the technical feasibility of using mixed recycled demolition aggregates in block production, aiming to reintegrate them into the construction chain and generate new sustainable materials. For this purpose, the study was conducted by the research group of the Federal University of Alagoas, using the waste provided by the company Braskem. The recycled aggregates were collected, processed, underwent an impurity removal process and characterization procedures. After these steps, a unifactorial experimental design was adopted, with granulometry as a factor, using the following aggregate combinations: 100% natural, recycled fine and natural coarse and natural fine and recycled coarse, in order to determine the influence of these combinations on the axial compressive strength of the blocks. For the dosage study, the optimum composition was defined, by means of the granular skeleton, in addition to the compressive rheometry technique being performed to determine the optimum moisture content. In the block production stage, a new dosage study was carried out, with the objective of determining the optimum moisture content for the blocks. The results indicated that the blocks produced with recycled sand and natural crushed stone were the only ones that presented characteristic strength for structural blocks. In addition, statistical tests proved, at a significance level of 5%, that blocks with recycled sand and natural crushed stone presented significant differences in their average strength when compared to the other sets of blocks (natural and combination with natural sand and recycled crushed stone). Therefore, it is possible to produce recycled blocks that meet NBR 12118 (2013) for structural purposes.