Maximising the benefits of calcium carbonate in sustainable cements: opportunities and challenges associated with alkaline waste carbonation

Abstract

Cement production significantly contributes to global climate change and implementation of carbon capture, utilisation and storage (CCUS) in construction materials is considered a crucial step toward achieving net-zero emissions. Substituting Portland cement (PC) clinker with limestone has been demonstrated to effectively reduce CO2 emissions while enhancing the properties of cement and concrete. Beyond limestone extraction, quarrying, and crushing, various types of alkaline waste materials generated from industrial processes can serve as valuable resources for producing diverse forms of calcium carbonate, simultaneously capturing a substantial amount of CO2. In this context, we contend that due to the distinct characteristics of various calcium carbonate forms, there exists the substantial potential to maximise their technical, economic, and environmental advantages in the production of sustainable cements. We reviewed existing studies of the effects of different calcium carbonate forms on cement properties and underscored the viability of utilising various alkaline wastes to produce different calcium carbonate products. As a promising approach for CO2 reduction, waste management, and resource recovery, we addressed the opportunities and challenges associated with advancing CCUS through the utilisation of carbonated alkaline wastes in sustainable cements. To achieve real-world impacts, we emphasised the necessity for interdisciplinary research collaborations, active involvement from industry stakeholders, regulatory bodies, and governmental support to facilitate the large-scale adoption of these innovative practices.