Role of Anionic Group of Methylallyl Ether-Based PCEs on Behavior of Cementitious Systems with Various C₃A Contents

In this study, the performances of methylallyl ether (HPEG) type polycarboxylate ether-based water reducing admixtures (PCE) partially substituted with phosphate and sulfonate anionic groups were investigated. The effects of synthesized PCE's on the fresh, rheological, and some hardened properties of mixtures prepared with cements having different C(3)A contents were examined. Increasing the phosphate and sulfonate substitution ratio of PCE up to a certain value improved the rheological properties of the mixtures. Best flow retention and rheological properties were obtained with 9% phosphate (P9) and 7% sulfonate (S7) PCEs. Due to the high PCE dosage used in the Marsh-funnel and mini slump experiments, the nonadsorbed PCE in the pore solution blocked the adsorbed polymers on the cement particles. Also, the hydrodynamic radius of the polymer had a significant effect on the adsorption and dispersion performance of PCE. Morover, with the increase of cement C(3)A content, the fresh properties of the mixtures were adversely affected. However, the increase in C(3)A content up to a certain value improved the hardened properties of the cementitious system. (c) 2024 American Society of Civil Engineers.