Title: Effect of Hydroxycarboxylate on the Hydration and Properties of High-Belite Calcium Sulphoaluminate Cement

Author(s): Ruifeng Tang, Ziming Wang, Mingzhang Lan

Publication: Symposium Paper

Volume: 354

Issue:

Appears on pages(s): 287-296

Keywords: hydroxycarboxylate, calcium sulfoaluminate cement, ettringite, retardation, high belite

DOI: 10.14359/51736082

Date: 7/1/2022

Abstract:
The cement industry is one of the major contributors to the world’s CO₂ emissions; the theoretical carbon emissions from Portland cement (PC) and calcium sulphoaluminate (CSA) cement are 535kg per ton and 305kg per ton, respectively, amounting to at least 5% of global anthropogenic emissions. More recently, a high-belite calcium sulphoaluminate (HB-CSA) cement has been developed, and the CO₂ emissions are lower than PC and CSA cement. Beyond that, this kind of cement shows excellent mechanical properties, volume stability, and good resistance to chemical attacks. But the rapid hydration and early setting times severely hinder the application of this green low-carbon cement in concrete. Therefore, this study investigated the use of citric acid (CA) and sodium gluconate (SG) with HB-CSA cement, tracking the effects of dosage on hydration, setting, fluidity, and strengths. Results showed CA effectively inhibited early hydration of the HB-CSA cement and successfully retarded the setting time while the retardation effect of SG was limited. Increasing CA and SG dosage altered hardened binder microstructure, reducing early-age compressive strengths and hydration heat rate, improving late-age compressive strengths. The difference in adsorption rate between CA and SG may be an important factor affecting their retardation effect of hydration.