Recycling of concrete construction and demolition waste in alternative binders: Part 2 - Environmental footprint

The concrete demolition and construction waste (CDW) is usually recycled as aggregate. The fine fraction (crushed sand and powder) obtained from the recycling process remains less recovered - for downcycling purposes such as backfilling, if recovered at all. The feasibility study on the recycling of concrete waste as a component of a blended binder is presented in Part 1 of the study. Part 2 is dedicated to a preliminary assessment of the environmental impacts of the partial replacement of Portland cement binder by a waste concrete powder (WCP). The assessment is focused on the binder production stage as per BDS EN 15804 and does not consider any further scenarios. The environmental impacts of alternative binders with a different amount of WCP is compared to the impacts of conventional cement types CEM I, CEM II/A and CEM II/B. The results confirm that there is a significant reduction of the environmental impacts when WCP is used for cement replacement, because of the more efficient use of material resources and energy. The effect is more pronounced with the higher replacement rate. Therefore, the use of WCP in cements leads to more eco-friendly binders and can contribute to closing the concrete loop.