The effect of carbonation accelerator on enhancing the carbonation process and mechanical strength of air-hardening lime mortars

• Published in: Construction & building materials 2024-04, Vol.425, p.136067, Article 136067
• Main Authors: Jia, Mengjun, Zhao, Yifan, Wu, Xuan, Ma, Xiao
• Format: Article
• Language: English
• Subjects: Air-hardening; Carbonation accelerator; Carbonation process; Lime mortars; Mechanical strength
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2024.136067

Ammonium carbonate was used as the carbonation accelerator for air-hardening lime mortars in this study. Various analytical methods, including XRD, IR, TGA-DSC and SEM were employed to access the phase transformation, degree of carbonation and microstructural features of the lime-based mortars. The paper explores the correlation between the mechanical strength, microstructure of cured lime mortars and the composition/carbonation degree with the crystallization behaviors in Ca(OH)2/CaCO3 binders. The results indicate that ammonium carbonate significantly accelerates the carbonation reaction and increases the early mechanical strength of air-hardening lime mortars. The mechanical strength of these modified lime mortars can be comparable to that of natural hydraulic lime (NHL). The aggregation behaviors of nano-CaCO3 under kinetic control, are believed to contribute much to the compact pore-structures and robust mechanical strength of lime mortars. This viable accelerating carbonation method holds promise for enhancing the properties of various lime-containing building materials in conservation and modern buildings. •Ammonium carbonate is effective in accelerating the carbonation of aerial lime.•Lime mortars modified by ammonium carbonate rival natural hydraulic lime (NHL).•The mechanical strength is highly related to carbonation degree and pore structure.•Nano-CaCO3 play pivotal role in compacting the pore structure of lime mortar.