ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

The formation process of aluminum hydroxide in calcium sulfoaluminate pastes

Fei Song, Yinong Lü, Honggang Qin, Yunfei Liu, Jian Xiao, and Wenjuan Liu

College of Materials Science and Engineering, Hunan Provincial Key Laboratory of Advanced Materials for New Energy Storage and Conversion, Hunan University of Science and Technology, Xiangtan, China

E-mail: songfei@hnust.edu.cn

Received: 9 July 2020  Accepted: 9 September 2020

Abstract:

Aluminum hydroxide phase (AH₃) is one of the hydration products for calcium sulfoaluminate. In this paper, the microstructure and formation process of AH₃ at different temperatures and water/solid ratios were investigated via scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results suggest that not only a high water/solid ratio but also a high temperature promoted the formation of AH₃, and changed the microstructure of AH₃. The AH₃ with various morphologies, formed together with ettringite and monosulfate, were found and confirmed in the pastes. The filamentous and lamellar AH₃ were observed in the early stages. Then, the AH₃ often gathered and grew forming smooth or lamellar spherical AH₃. At last, the spherical AH₃ usually continued to aggregate, forming dense or lamellar agglomerated AH₃ in the later stages.

Keywords: Calcium sulfoaluminate; Hydration; Aluminum hydroxide; Ettringite; Monosulfate

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-020-01351-7

Chemical Papers 75 (3) 909–920 (2021)