Glass wool residue: a potential supplementary cementitious material

Abstract

Glass wool is employed on several industrial and building applications as insulation, but at the end of its lifecycle, the material loses its properties, becoming glass wool residue. This residue does not have an established recycling method and generally ends up on landfills with high management costs and environmental impacts. However, its chemical composition and amorphous content are consistent with pozzolan-like supplementary cementitious materials with potential use by the construction industry. In this sense, the present work proposes a performance study of glass wool residue in cement-based composites. Experiments were performed on mortars and pastes with 25% portland cement replacement by grinded glass wool residue. Thermal analysis and X-ray diffraction of the pastes confirmed the pozzolanic properties of this by-product. The results showed an increase in the formation of calcium silicate hydrate, followed by a calcium hydroxide consumption of 37% and 44% at 28 and 56 days, respectively. Additionally, the compressive strength tests showed similar performances for residue and reference mortars with a reduction of only 2% of compressive strength. The glass wool mortars reached cement savings of 24% and an improvement of the binder intensity to 15.5 kg·MPa–1·m–3. In conclusion, the use of grinded glass wool residue improved the portland cement efficiency, reducing the consumption of natural resources and CO2 emissions related to the clinker production.