Developing carbon-neutral construction materials using wastes as carbon sink

Abstract

Developing ecofriendly and low-carbon construction materials is essential to meet the ambitious target of global net zero emission by 2050. The concept of using wastes as carbon sink is taking advantage of alkaline solid wastes, which are rich in calcium or magnesium as a medium for absorbing carbon dioxide (CO2), and allowing manufacturing thermodynamically stable carbonate minerals for construction applications. Today, the major practical and successful applications of CO2 in the construction industry are through accelerated carbonation of granulated aggregates and precast concrete blocks manufactured with different proportions of calcium-rich waste materials. CO2 is also used as an activator in speciality nonhydraulic carbonate-binders or directly injected (in a liquid form) into fresh ready-mix concrete to produce a construction material with higher strength and lower carbon footprint. In addition, accelerated carbonation has become a promising approach to improve the quality of crushed concrete waste, and can be reused in new concrete to attain a sustainable concrete life cycle. In this paper, the progress in academic research of using CO2 in wastes and cement-based products as well as the key advantages and limitations related to the large scale application in the construction industry have been discussed in detail.