Espumas produzidas com vidro reciclado e cinza de casca de arroz: avaliação para potenciais aplicações como isolante térmico em forros

Abstract

Nowadays, climate change intensified by anthropogenic actions has increased thermal discomfort inside buildings, driving the increase of energy consumption and worsening environmental impacts. This study investigated the production of sustainable glass foams from recycled glass, rice husk ash (RHA) and calcium carbonate (CaCO3) as a foaming agent for thermal insulation purposes. In addition, the foam identified as the most efficient in the study was applied as a gypsum ceiling coating in a prototype built with ceramic brick masonry to simulate a real-world application scenario. Glass foams with different contents (95%, 97.7%, 98% and 100%) of recycled glass and RHA in proportions of 80% and 20% respectively and varying concentrations of CaCO3 (5%, 2.5%, 2% and 0%) were produced at different sintering temperatures (950 °C, 1000 °C and 1030 °C). Analyses of the properties of the produced foams showed that the composition containing 98% of the mixture (80% glass + 20% RHA) and 2% CaCO3 sintered at 1000 °C proved to be the most efficient for thermal insulation applications. The described foam exhibited an apparent density of 0.29 ± 0.05 g/cm3, thermal conductivity ranging from 0.1195 ± 0.0069 W/(m•K) to 0.1270 ± 0.0101 W/(m•K), average pore diameter of 1.827 ± 0.749 mm, porosity of 88.1% and axial compressive strength of 0.81 ± 0.14 MPa. A panel of this foam with an average thickness of 20 mm and dimensions of 1.32 m x 1.32 m was produced and applied as a gypsum ceiling coating in a masonry prototype. A second prototype with equivalent characteristics was used as a reference. Temperature and humidity data were collected for 48 hours. It was found that the incorporation of glass foam as a coating delayed heat transfer between the ceiling surfaces, which demonstrates the material effectiveness for thermal insulation when applied under the described conditions. In this regard, the results obtained showed that the glass foams produced in this study, in addition to being effective in promoting thermal insulation, they represent an environmentally responsible alternative which contributes to waste reduction and weaken the demand for energy and raw materials of natural origin. Keywords: Glass foams. RHA. Sustainability. Thermal insulation.