Uso de agregados leves à base de resíduos de poliéster e laminado de PVC extrusados com poliestireno em matrizes cimentícias

Abstract

The generation of waste from different sectors of the Brazilian economy has generated studies and research related to the consumption and disposal of the most varied products. In this context, the industries of the footwear sector, traditional in the State of Rio Grande do Sul, are inserted, which have the need to seek sustainable actions in the reuse of leftover raw materials from the production of footwear. Therefore, this work aimed to evaluate the use of a lightweight aggregate based on polyester waste and PVC laminate extruded with recycled polystyrene in cementitious matrices. Reference mortars were prepared with a mass ratio of 1:3 (cement: dry sand) and a water/cement ratio (w/c) of 0.48. Another four mortars were prepared with levels of replacement of quartz sand, in volume, by light aggregate, at 25%, 50%, 75% and 100%. The results in the fresh state of the mortar show that the workability reduced with the increase in the percentage of light aggregate in the mortar. In the hardened state, increasing the percentage of lightweight aggregate led to an inverse behavior for compressive strength and specific mass, and a direct behavior for water absorption, porosity and void ratio. With the aid of the scanning electron microscope (SEM) it was observed that the thickness of the microcrack between the quartz sand and the hydrated cement paste was smaller when compared to the thickness of the microcrack between the lightweight aggregate and the cement paste after compressive strength tests , which indicates that the lightweight aggregate makes this region less resistant, which corroborates the 86% drop in compressive strength at 28 days between the reference matrix and the matrix containing 100% lightweight aggregate. By energy dispersive spectroscopy (EDS) the chemical elements present on the surface of the samples were verified. Fourier Transform Infrared Spectroscopy (FTIR) identified the characteristic functional groups of materials and cementitious matrices at 7 and 28 days. With the aid of X-ray diffraction (XRD) it was observed that the intensity of the characteristic peaks of quartz reduced as there was an increase in the replacement of quartz sand by light aggregate in the cementitious matrices.