Carbonation potential of recycled aggregates from construction and demolition waste

Abstract

One of the biggest challenges currently faced by Society is climate change, leading to the need of mitigation of carbon dioxide (CO2) emissions, among other consequences. The construction sector is responsible for a large part of these emissions. In addition, this sector is also responsible for a significant part of all waste globally produced, about one third in the European Union. The use of construction and demolition wastes (CDW) as aggregates in mortars and concrete has been the objective of several studies. This incorporation reduces the volume of natural aggregates used in these construction products, decreasing the depletion of natural resources, while increasing the life cycle of the incorporated by-products. It thus contributes to the reduction of the environmental impacts of the construction sector. Nevertheless, recycled aggregates are not often incorporated in mortars and concrete due to their higher porosity and lower strength compared to natural aggregates. Jointly with the Portuguese cement industry, this research intends to produce more sustainable mortars and concrete by using CDW aggregates as a carbon capture and storage source. This not only reduces the global greenhouse emissions of concrete but also potentially improves the CDW aggregates’ properties. To this extent, different types of CDW aggregates will be subjected to forced and accelerated sequestration of CO2, contributing to the capture of part of the CO2 emissions of the Portuguese cement industry, providing it with more sustainable processes. As a result, this study intends to contribute to the reduction of non-renewable natural resources, in the form of natural aggregates, while reusing CDW and capturing part of the CO2 released by the production of cement. This article presents the characterization of three CDW from different origin and treatments, regarding the analysis of their carbonation potential.