GUAN X M, WANG X Q, ZHI Z Z. column: Effects and mechanisms of polycarboxylate superplasticizer on the hydration and hardening behavior of construction-grade desulfurized  gypsum[J].Journal of Henan Polytechnic University(Natural Science) ,2025,44(5):187-192.

DOI:10.16186/j.cnki.1673-9787.2023120038

Received:2023/12/13

Revised:2024/02/22

Published:2025/07/23

Effects and mechanisms of polycarboxylate superplasticizer on the hydration and hardening behavior of construction-grade desulfurized  gypsum

Guan Xuemao1, Wang Xueqing1, Zhi Zhenzhen2

1.School of Materials Science and Technology， Henan Polytechnic University， Jiaozuo  454000， Henan， China；2.School of Materials Science and Technology ， Luoyang Institute of Science and Technology， Luoyang  471023， Henan， China

Abstract: Objectives To improve the performance of hardened desulfurized gypsum and promote the resource utilization of by-product gypsum from flue gas desulfurization in coal-fired power plants， a polycarboxylate superplasticizer （PCE） was synthesized， and its effects on the hydration and hardening behavior of β-hemihydrate desulfurized gypsum （β-HDG） were investigated. Methods The influence of varying PCE dosages on the fluidity， adsorption behavior， and zeta potential of β-HDG slurry， as well as the compressive and flexural strengths of hardened specimens， was studied. X-ray diffraction （XRD） and scanning electron microscopy （SEM） were employed to analyze the crystal phase composition and microstructure of the hardened gypsum. Results As the PCE dosage increased， both slurry fluidity and water-reducing efficiency first increased and then stabilized. At a dosage of 0.4%， the slurry exhibited a maximum fluidity of 248 mm and a 26% water-reduction rate， with standard consistency water demand reduced to 37%. The adsorption capacity of PCE on gypsum surfaces also increased and then stabilized with prolonged adsorption time， reaching a saturation value of 3.6 mg/g at 0.4% dosage. The zeta potential of the slurry decreased with increasing PCE content. The compressive and flexural strengths of the hardened gypsum peaked at 24.7 MPa and 5.81 MPa， respectively， representing increases of 32.6% and 21.5% over the blank sample. Conclusions The addition of PCE improves slurry workability and reduces water demand for standard consistency， thereby enhancing the mechanical strength of hardened desulfurized gypsum. While the crystal phase composition remains unchanged， the denser networked crystal structure and lower porosity contribute significantly to the improved macro-strength of the hardened product.

Key words:-Hemihydrate desulfurized gypsum;polycarboxylate superplasticizer;hardening;flexural strength;compressive strength