A review on the impact of water in accelerated carbonation : implications for producing sustainable construction materials

Abstract

The construction industry has been facing significant challenges in reducing CO<inf>2</inf> emissions. As such, accelerated carbonation has attracted explosive attention in view of its ability to bind CO<inf>2</inf> back to construction materials while improving their performance. Water is a decisive factor in carbonation because it bridges the reaction between gaseous CO<inf>2</inf> and solid precursors, and three distinct approaches of carbonation have been developed depending on the amount of water present at carbonation. In this paper, specific roles of water in several parallel mechanisms of carbonation are revealed and then a holistic understanding on the impact of water is established by reviewing and comparing the efficiency, mineralogy and microstructure changes of cementitious materials and calcium-based solid wastes after dry, semi-wet, and wet carbonation. The differences in solid phase dissolution, calcium carbonate precipitation and re-crystallization, aluminosilicate polymerization, microstructure rebuilding, pore structure evolution, specific surface area development, etc. at different water availability are highlighted. Additionally, modified carbonation techniques based on different water content are also summarized and discussed. Overall, awareness of water's impact on carbonation facilitates the efficient and effective production of sustainable construction materials and maximizes the reduction in CO<inf>2</inf> emission.