Evaluating The Impact of Waste Glass Powder Cement Replacement on The Embodied Carbon of Bridges

Construction of bridges is a major source of global carbon emissions, primarily because of the extensive use of concrete which includes the cement which is the most carbon-intensive constituent in concrete. In order to reduce the environmental impact, this study examines the use of waste glass powder (WGP) as a substitute for cement. The objective of this study is to evaluate the potential reduction in embodied carbon in bridge deck construction by substituting WGP for a portion of Ordinary Portland Cement (OPC). The environmental effects of several concrete mix designs have been estimated and compared using a theoretical approach that relied on secondary data from the literature. Literature evidence suggests that WGP (particle size 45-75 µm) enhances compressive strength at 10-15% replacement levels because of pozzolanic reactions, but strength reduces at higher percentages. Carbon saving calculations based on ICE database parameters indicate 4.40-19.10% savings, with better-quality mixes like C35/45 resulting in greater absolute savings and poorer-quality mixes like C16/20 giving maximum relative savings. In a 20-meter bridge deck design case study, a saving of 200 kgCO₂ per metre was achieved through the use of 10% WGP substitution, satisfying BS 5400 performance requirements. Besides lowering the requirement of cement and recycling waste glass, WGP supports circular economy. Even though the energy required to produce WGP and aggregate uncertainty are not taken into consideration in this study, the case study shows that using WGP can lower embodied carbon by about 19.6%, indicating its potential to contribute to environmental sustainability.