Effect of carbonation curing regime on strength and microstructure of Portland cement paste

•Optimal pre-curing duration decreases as the prolongation of carbonation duration.•Carbonation could retard hydration reaction of cement paste.•Proper pre-curing reduce differential of porosity and pore size among depth.•Excessive carbonation can lead to decalcification of C-S-H and decrease of str...

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Bibliographic Details
Published inJournal of CO2 utilization Vol. 34; pp. 74 - 86
Main Authors Chen, Tiefeng, Gao, Xiaojian
Format Journal Article
LanguageEnglish
Published Elsevier Ltd 01.12.2019
Subjects
Carbonation curing
Carbonation duration
Compressive strength
Microstructure
Pre-curing
Carbonation duration
Carbonation curing
Compressive strength
Microstructure
Pre-curing
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Summary:•Optimal pre-curing duration decreases as the prolongation of carbonation duration.•Carbonation could retard hydration reaction of cement paste.•Proper pre-curing reduce differential of porosity and pore size among depth.•Excessive carbonation can lead to decalcification of C-S-H and decrease of strength. This study aims to investigate the effects of pre-curing and carbonation duration on compressive strength and microstructure characteristics of Portland cement paste. Experimental results showed that 30–40% water loss of cement paste is ideal for CO2 uptake. The combination of appropriate pre-curing and carbonation duration could increase compressive strength of cement mortar effectively, especially at early age. The optimal pre-curing duration decreases as the carbonation duration increases. Thermogravimetric analysis indicated that carbonation could retard hydration of cement paste and higher concentration of CO2 increases crystallinity of carbonate. According to MIP results, the influence of hydration and carbonation on pore structure of cement paste is different. Carbonation could decrease large capillary porosity obviously while hydration fills small capillary first. In addition, it is observed from EDS point analysis that excessive carbonation lead to decalcification of C-S-H. Therefore, suitable pre-curing and carbonation duration is of significance to improve the strength and microstructure of cement pastes.
ISSN:2212-9820
2212-9839
DOI:10.1016/j.jcou.2019.05.034