Effect of Seawater on Hydration Process and Mechanical Properties of High Belite Calcium Sulphoaluminate Cement

Abstract

Abstract: The compressive strength and flexural strength of high belite calcium sulphoaluminate cement (HB-CSA) and ordinary Portland cement (OPC) mortars with seawater mixing and seawater curing were measured. The hydration processes and hydration products of HB-CSA and OPC were characterized by isothermal calorimetry, X-ray diffraction and thermogravimetric analysis. The effect of seawater on hydration process and mechanical properties of HB-CSA was analyzed. The results show that seawater mixing doesŃt significantly affect the early hydration process of HB-CSA, and seawater mixing and seawater curing doŃt change the types of main hydration products. Seawater mixing significantly accelerates the early hydration of OPC. Chlorine in seawater reacts with OPC hydration products, resulting in the formation of Friedel's salt. Seawater mixing and seawater curing have little effect on the compressive strength of HB-CSA mortar, but reduce the compressive strength of OPC mortar in the later age. Seawater curing significantly improves the flexural strength of HB-CSA and OPC mortars, and the increase of AFt content is the main reason for the increase of flexural strength. Because Ca(OH)₂ and AFm are not found in the hydration products of HB-CSA, the damage of concrete expansion cracking and strength decline caused by generation of excessive CaSO₄·2H₂O and AFt after seawater intrusion are avoided.

Key words: high belite calcium sulphoaluminate cement, seawater, hydration process, hydration product, mechanical property

CLC Number:

TQ172

ZHENG Juan, LI Hui, XU Mingfeng, ZHOU Jian, CHEN Zhifeng, ZHANG Zhenqiu, LIU Chengjian, ZHANG Jianbo. Effect of Seawater on Hydration Process and Mechanical Properties of High Belite Calcium Sulphoaluminate Cement[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2021, 40(9): 2898-2904.

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