Incorporação de PET triturado em substituição parcial ao agregado miúdo para utilização em argamassas.

Abstract

Polyethylene terephthalate (PET), due to its versatility and low production cost, has become one of the most widely used plastic materials worldwide. However, it is an environmental problem, due to the prolonged stay in the environment and inadequate disposal, which contributes to the accumulation of large volumes in nature and in landfills. In response to this issue, the civil construction industry has great potential for incorporating waste from other production systems. Thus, this work aims to evaluate the physical, chemical, mineralogical and mechanical properties, and the durability of laying and coating mortars, produced with partial replacement of fine aggregate by crushed PET. For this purpose, two mixes were formulated with different proportions of binders and fine aggregate, in which Portland cement CP ll Z-32, lime, sand and crushed PET were used, in partial replacement of 5%, 10%, 15%, 20% and 25%. The physical characterization was carried out through tests to determine the specific and unitary mass and the sieving and leisure granulometry of the constituent elements. For the chemical characterization, the techniques of X-ray fluorescence spectrometry, thermogravimetric analysis (TGA), differential thermal (DTA) and X-ray diffraction (XRD) were used. The physical and mechanical properties were determined from the mass density and incorporated air content, in the fresh state. In the hardened state, density, simple compressive strength (SCS), flexural tensile strength, capillary water absorption and tensile bond strength (TBS) were measured. In the durability study, the resistance to attack by sulfates was used. The increase in PET content in partial replacement of fine aggregate reduced the water/binder ratio by up to 15%. As a result, there are gains in the workability of mortars as a result of the greater availability of free water. It was found that the increase in PET content reduced the water/binder ratio by up to 15%. There were gains in the workability of the mortars, given the greater availability of free water. In the fresh state, the mass density decreases linearly as the percentage of PET increases, with differences of up to 11.48%. The content of incorporated air increases, however, it tends to decrease when the percentage of partial replacement exceeds 15%. In the hardened state, there is also a decrease in density due to the increase in the PET content, reaching 15.81%. As for the SCS and the flexural tensile strength, for the 1:2:9 mix, there was an increase both with the incorporation of PET and with the curing age, for the mortars with contents of 10%, 15%, 20% and 25% PET, after 14 days. For the 1:1:6 mix, after 28 days of cure, it is noticed that the mortar without the addition of PET showed better performance for these mechanical parameters. However, at 56 days of cure, all mortars with PET additive showed greater strength. The insertion of PET reduced capillary water absorption, however, there was a reduction in the TBS. Regarding the attack by sulfates, they are considered reactive, as they undergo dimensional expansion when immersed in sodium sulfate solution.