Fully utilizing carbonated recycled aggregates in concrete: Strength, drying shrinkage and carbon emissions analysis

• Published in: Journal of cleaner production 2022-12, Vol.377, p.134520, Article 134520
• Main Authors: Xiao, Jianzhuang, Zhang, Hanghua, Tang, Yuxiang, Deng, Qi, Wang, Dianchao, Poon, Chi-sun
• Format: Article
• Language: English
• Subjects: Carbon emission analysis; CO2 treatment; Drying shrinkage; Fully recycled aggregate concrete (FRAC); Recycled coarse and fine aggregate
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2022.134520

In this study, natural aggregates, recycled aggregates (RAs), and carbonated RAs were combined to prepare concrete. Strength, drying shrinkage, microstructures, and the carbon emissions of concrete prepared with different aggregate combinations were explored and compared. The results show that the compressive strengths of carbonated fully recycled aggregate concrete (CFRAC) increased by 20.9% and the drying shrinkage at 180 days decreased by 23.3% compared with that of concrete with RAs due to the reduction of water absorption of RAs and the additional water. The pore structure of CFRAC was densified and improved by carbonation treatment on RAs. Furthermore, the carbon emission analysis showed that CFRAC had 7.1%∼13.3% lower carbon emission and 13.4%∼18.4% lower CO2 intensity than natural/recycled aggregate concrete due to the shorter transportation distance and the carbon absorption. Generally, CFRAC had improved properties and environmental benefits, which shows carbonation treatment is a valuable way to promote waste concrete recycling. [Display omitted] •Carbonated recycled aggregates (CRAs) improve concrete strength and reduce variability.•CO2 treatment for recycled fine/coarse aggregates reduces the shrinkage of concrete.•CRA concrete has environmental benefits due to low CO2 emission and high strength.