Chapter 6. Assessing the Environmental Benefits of Using Glass Powder as a Supplementary Cementitious Material in a Context of Open-loop Recycling

Although it is an abundant recyclable resource, mixed colour waste glass does not meet quality standards to be recycled and is often landfilled in Quebec (Canada). Glass powder (GP) has been shown to have pozzolanic properties; it therefore has potential application in the concrete industry as an alternative supplementary cementitious material. The construction of a concrete pedestrian bridge provides an opportunity to compare the potential environmental impacts of three different types of concrete: conventional concrete and two mixtures of ultra-high-performance concrete (UHPC), conventional UHPC (Conv-UHPC) and UHPC incorporating GP as a partial replacement for Portland cement (Glass-UHPC). Such a comparison was conducted using the Life Cycle Assessment methodology. The results highlight the environmental benefits of using UHPCs rather than conventional concrete in every impact category. As an example, building the bridge using Conv-UHPC and Glass-UHPC resulted in a 42% and 53% decrease in greenhouse gas emissions compared with that of conventional concrete, respectively. The same results were also observed when comparing the two UHPCs. Indeed, the incorporation of GP led to a decrease of 3–20% in all environmental categories of the final results, in comparison to those of the Conv-UHPC. However, these conclusions depend on the effective life span of the concrete (120 years for the UHPCs and 50 years for the conventional concrete).