Environmental solutions in concrete: Evaluating class C fly ash and crushed glass as sustainable replacements

Abstract

This study investigates the environmental impact of concrete, which is the second most consumed material after water. While concrete is vital for the construction industry, its production contributes significantly to carbon emissions, raising concerns about its sustainability. This research proposes the use of fly ash and crushed glass as partial substitutes for cement and fine aggregate, respectively, to mitigate these environmental effects. Unlike most prior research that utilizes class F fly ash, this investigation focuses on class C fly ash, sourced locally in New Zealand, thereby enhancing its relevance to regional practices. To evaluate the effects of these alternative materials on concrete properties, a series of experiments were conducted, including slump tests and compressive strength tests. A concrete mix design of 1:1:2 was employed, incorporating various levels of fly ash substitution 10%, 18%, 26%, and 34% for cement, alongside crushed glass substitutions ranging from 10% to 34% in sand, with increments of 8% per set. The results demonstrated that the incorporation of fly ash and crushed glass not only contributes to a reduction in carbon emissions associated with concrete production but also enhances the compressive strength of the concrete when compared to the control mixture. This study highlights the potential for using these alternative materials to promote more sustainable concrete practices while improving material performance.