Análise da viabilidade de utilização de brita leve (EVA) em concretos de cimento Portland

Abstract

The use of solid waste in cementitious matrix composites has shown promising results in the last decades, especially for providing a final destination to non-biodegradable materials and for reducing natural aggregates extraction. This paper aims to analyze the feasibility and the influence of poly (ethylene co-vinyl acetate) - EVA - wastes additions on the Portland cement concrete mechanical strength. The EVA wastes were not processed at any time. The EVA waste characterization was carried out using X-Ray Fluorescence (XRF) spectroscopy and Termogravimetric Analysis (TGA) techniques. The EVA waste, that had similar granulometric compositions, was used as part substitutes of fine gravel and two mixtures were made (50% and 100% substitution, in volume). From each mixture, eight cylindrical shaped specimens, according to the NBR 5738 Brazilian Standard, and two rectangular floor plates were prepared. Eight cylindrical specimens were also made with no aggregate substitution in order to be the reference material. Axial compression tests were carried out according to the Brazilian Standard NBR 5739 and tensile strength through diametral compression test according to the NBR 7222, by the age of 28 days for both tests. EVA waste has shown significant amounts of calcium carbonate, a compound that can lead to corrosion of steel reinforcement in concrete. In addition, it could be verified an average vinyl acetate proportion of 28% and thermal stability until 300ºC. Lightweight concrete was produced due to the substitution of fine gravel in both mixtures with specified EVA volumes. For both mixtures it was also noticeable the compression and tensile strength reduction with the EVA volume substitution increase. The highest axial compression strength was observed at the reference material (23,10 MPa), and the lowest strength was observed at the mixture of 100% aggregate substitution (0,98 MPa). The concrete produced from EVA waste substitution is a lightweight concrete with non-structural application. The floor plate shown to be feasible for the dimensions produced.