Caracterização tecnológica de resíduos de construção e demolição reciclados para aplicação em estruturas de contenção utilizando gabiões

Abstract

The civil construction sector has national economic importance, but its main environmental liability is the generation of Construction and Demolition Waste (CDW), which can correspond to about 50 to 70% of the total volume of urban solid waste in Brazil. In this context, there is a global movement that aims to reduce the generation of CDW, minimize the waste of construction materials, as well as find new applications. Considering that the inert fraction of CDW (RCC Class A according to CONAMA Resolution 307/2002) is the one that constitutes the largest mass in the generated waste and is close to the characteristics of natural aggregates, there is a great potential for its use in total or partial replacement of natural aggregates for various purposes. In this way, this work aims to evaluate the physical and mechanical characteristics of the inert fraction of CDW, aiming to analyze its performance as a filling material in containment structures using gabions. Gray fraction (cement materials and ornamental rocks), red fraction (ceramic materials) and mixed fraction of recycled aggregates from the SLU-PBH CDW recycling plant (ERE BR-040) were studied, more specifically the fraction called “rachão” (characteristic dimensions between 5 and 20 cm). The experimental program involved carrying out characterization tests (gravimetric composition, moisture content, unit mass, shape index and water absorption) and mechanical performance tests (Los Angeles abrasion and point compressive strength). The gravimetric composition indicated a predominance of gray fraction, with 77%, followed by 13.2% of mixed aggregates and 8.5% of red fraction. The unit mass obtained varied between 1213 and 1097 kg/m and the Los Angeles Abrasion, between 57 and 62%, for the gray and composite samples (50% gray - 50% red). The water absorption results ranged from 8.8 to 18% for the gray and red fractions, respectively. The point compressive strength index ranged from 10.11 to 0.012 MPa, corresponding to rocky and ceramic materials. As for durability, a test that simulates weathering, the red fraction obtained wear of 95.0%, the gray fraction of 95.5% and the mixed fraction of 96.3%, considering two cycles. The gray fraction obtained the best unconfined compression result with an average stress of 38.0 kPa, while the red fraction obtained 25.4 kPa. The results suggest that the gray fraction of recycled CDW has greater potential for its intended use.