Synthesis and Properties of Water-Reducing and Slump-Protecting Polycarboxylate Superplasticizer

Abstract

Abstract: The water-reducing and slump-protecting polycarboxylate superplasticizer (V-HEA) was prepared by free-radical polymerization with 4-hydroxybutyl vinyl polyoxyethylene ether (VPEG) macromonomer and acrylic acid (AA) as the main raw materials by adding the slump-preserving monomer hydroxyethyl acrylate (HEA), and mercapto-propionic acid (MPA) as chain transferr agent under the H₂O₂/L-vitamin C (V_C) oxidation-reductioninitiator system. The synthesized V-HEA was characterized by infrared spectroscopy, gel chromatography testing, and it was subjected to hydration heat analysis and concrete performance comparison analysis with commercially available slump-preserving polycarboxylate superplasticizer (HPWR-S). The results show that the optimal synthesis process parameters of V-HEA are acid-ether ratio of 4.4, ester-ether ratio of 2.5, and the dosage of initiator, ferrous sulfate and chain transfer agent accounted for 0.76%, 0.10% and 0.74% of the mass of the macromonomer, respectively. The incorporation of ferrous sulfate could improve the conversion rate of monomers, and the number average molecular weight of V-HEA is 17 650, the weight average molecular weight is 42 713, and the conversion rate of monomers is as high as 95.03%. The peak temperature of hydration reaches by the incorporation of V-HEA is delayed by 4 h 24 min compared with HPWR-S, and the occurrence time of the second hydration rate peak is delayed by about 4 h, which further delays the hydration of cement. In comparison test of concrete performance, the 2 h slump only decreases by 5.8% with the addition of V-HEA, and the strength of concrete is comparable to that of HPWR-S products, so V-HEA has good application prospects.

Key words: polycarboxylate superplasticizer, VPEG macromonomer, radical polymerization, slump-preserving type, molecular structure characterization, hydration heat analysis

CLC Number:

TU528.042.2

DONG Jiantong, LIU Zhiyong, HU Zhongshuai, ZHU Dandan, DING Yi, ZHANG Weiqiang, LAI Fukun. Synthesis and Properties of Water-Reducing and Slump-Protecting Polycarboxylate Superplasticizer[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2024, 43(1): 52-60.

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