Carbonation of mortar with supplementary cementitious materials : comparison between water, sealed and calcium hydroxide curing

For the determination of the resistance to carbonation of mortar or concrete, different national and international standards are available prescribing various types of curing and preconditioning. Especially when a carbonation coefficient deduced from accelerated carbonation testing is used for comparing the performance of mixtures or for service life prediction, the applied boundary conditions during curing, preconditioning and carbonation play a crucial role in ranking these mixtures. Moreover, the importance of curing type to simulate natural behaviour through accelerated carbonation tests increases when using latent hydraulic or pozzolanic supplementary cementitious materials. For this reason, mortar specimens made with three different cement types (CEM I, CEM II and CEM III) and cured according to three different methods (water, sealed and Ca(OH)2 curing) were compared by investigating the corresponding carbonation coefficient after approximately 56 days of accelerated carbonation at a carbon dioxide concentration of 1%. The curing duration corresponds to EN 13295 and a preconditioning period of 28 days was applied. The results of two independent laboratories following the same aforementioned procedure were compared to investigate the reproducibility. Conclusions regarding the impact of curing type on the carbonation resistance were further investigated by Thermogravimetric Analysis (TGA). This experimental research supplements the interlaboratory test within the framework of RILEM TC 281-CCC which is currently ongoing