Reaproveitamento de polipropileno recuperado mecanicamente para a produção de material compósito de matriz cimentícia

Abstract

The construction industry is an important consumer of raw materials. However, it also has the potential for consuming waste and/or by-products from other industries, including the waste generated by construction. Aggregates are the most consumed materials in the world, second only to water. The use of cementitious matrices containing lightweight fine aggregate based on recycled polypropylene (LA) can contribute to reducing the environmental impact of construction, promoting sustainability and energy efficiency. Based on this context, this study aimed to evaluate the use of lightweight aggregate as a partial replacement for natural quartz sand in cement matrices. Reference mortars (M0) were prepared with a mass ratio of 1:3 (cement:sand) and a water/cement ratio (w/c) of 0.48. Three replacement levels, in volume, of sand by LA were studied: 25% (M25), 50% (M50), 75% (M75). The mortars were prepared keeping the w/c ratio constant at 0.48. Mortar consistency tests were carried out on the flow table test, mechanical tests (compressive strength) at ages of 7, 28 and 63 days, physical tests (water absorption, porosity, specific mass) at ages of 28 days. Complementary analyzes of the cement matrices were carried out using a scanning electron microscope (SEM) and an X-ray diffractometer (XRD) at ages 7 and 28 days. Using analysis of variance (ANOVA), the results of compressive strength were analyzed, which showed significant differences, as there was an increase in the replacement content of sand by light aggregate, there was a drop in axial compression resistance. In the water absorption and porosity tests, values increased according to the increase in sand replacement levels with light aggregate. Consequently, the specific mass values of the cement matrices decreased as the replacement of sand by light aggregate increased. In the analysis of the cement matrices with the Scanning Electron Microscope (SEM), less dense transition zones were identified between the lightweight aggregate and the cement paste, which may have contributed to the drop in compressive strength, as it generates weaker zones susceptible to rupture. In the X-ray diffraction analysis, there was no influence on the crystalline hydration products of Portland cement with the presence of light aggregate.