1 2 3 Internal curing with superabsorbent polymers of different chemical 4 structures 5

15 This study investigates the absorption behavior of superabsorbent polymer (SAP) with different 16 chemical structures and their effect on cement hydration, early-age autogenous shrinkage and 17 mechanical properties of cement paste. SAP with high density of anionic functional groups absorbed the 18 cement pore solution quickly, and then released it because the anionic groups on the network of SAP 19 complexed with multivalent cations in the pore solution (e.g., Ca2+). Much less release was measured 20 for SAP with low density of anionic groups. Furthermore, SAP with either both anionic and cationic 21 groups or with only non-ionic groups did not release the liquid. Despite their different behavior in 22 solutions, all SAP were able to counteract autogenous shrinkage. SAP with either both ionic groups or 23 high density of anionic groups showed excellent internal curing effect. The internal curing had no 24 This document is the accepted manuscript version of the following article: Zhong, P., Wyrzykowski, M., Toropovs, N., Li, L., Liu, J., & Lura, P. (2019). Internal curing with superabsorbent polymers of different chemical structures. Cement and Concrete Research, 123, 105789 (11 pp.). https://doi.org/10.1016/j.cemconres.2019.105789 This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ negative effect on the compressive strength of the paste when the total cement-to-water ratio was 25 considered. 26

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