Espumas de vidro a partir de resíduos vítreos: uma proposta de agregados graúdos para concreto leve

Abstract

Facing the challenges of the possible depletion of natural resources, this work proposes the use of waste glass to obtain foamed glass materials as a lightweight substitute for coarse aggregate in concrete in the construction industry. In this sense, powdered waste glass was mixed with polyvinyl butyral (PVB) as a plasticizing agent and industrial-grade manganese dioxide (MnO2) as the foaming agent, the mixture formed was heated for 30 minutes and then cooled until it reached ambient temperature. The synthesis process of glass-based foams was evaluated by a 23 full factorial design, considering the foaming agent amount (4.0 wt.% or 7.0 wt.%), heating rate (10 ℃/min or 15 ℃/min) and burning temperature (820 ℃ or 860 ℃). The chemical composition of the waste glass was accessed by X-ray fluorescence (XRF), while the particle size distribution was determined by static laser scattering (SLS). The characteristic temperatures of the foaming agent and powdered glass were determined by differential thermal analysis (DTA). Lightweight concrete of mix design 1:1.53:2.12:0.48 was characterized for bulk density, compressive strength and modulus of elasticity. The powder X-ray diffraction (PXRD) of the foamed glass materials showed a vitroceramic characteristic, indicating, to some extent, the presence of crystalline phases from manganese compounds, silicon oxide polymorphs, and an amorphous halo. The process for obtaining glass-based foams allowed lower apparent densities with the increase of heat exposure time. The compressive strength of the concretes produced reached 29.15 MPa after 28 days for the foam glass obtained with 7.0 wt.% of foaming agent and heating rate of 15 ℃/min up to 820 ℃. The modulus of elasticity of the concrete behaved analogously to the compressive strength, where the increase of foaming agent and temperature rate generate positive results. The use of glass-based foams as a coarse aggregate in concrete production promotes a sustainable and updated alternative for construction.