Ground recycled glass powder as a sustainable alternative to fly ash in low-carbon concrete

Abstract

The increasing limitation in the availability of traditional supplementary cementitious materials (SCM), particularly coal fly ash (FA), has intensified the need for alternative solutions capable of ensuring both technical performance and environmental sustainability in cement-based materials. In this context, waste glass derived from soda–lime glass emerges as a promising option, contributing to circular economy principles and to the reduction of CO₂ emissions associated with clinker production. The study, developed within the framework of the GlassCON_4low project, aims to evaluate the feasibility of using finely ground glass powder (GP) as a SCM, assessing its pozzolanic activity and its influence on the mechanical and durability performance of concrete. The research has two main phases. First, mortars are produced with cement replacement levels of 15%, 25%, 35% and 50% by volume. Their mechanical behaviour is assessed and complemented by thermogravimetric analyses. Second, based on these results of first, two replacement levels are selected to reproduce in concrete mixtures. The concretes are subsequently characterised in terms of compressive strength at 7, 28 and 90 days, as well as durability indicators, including water absorption by immersion and capillarity, chloride diffusion and resistance to carbonation. The outcomes of this study aim to demonstrate the technical feasibility of using GP as a SCM in concrete, contributing to the development of more sustainable and durable construction solutions aligned with current technical, environmental and resource-efficiency challenges.