Influence of water removal techniques on the composition and microstructure of hardened calcium sulfoaluminate cement pa
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ORIGINAL ARTICLE
Influence of water removal techniques on the composition and microstructure of hardened calcium sulfoaluminate cement pastes Min Liu . Shuqiong Luo . Lei Yang . Jun Ren
Received: 16 January 2020 / Accepted: 3 July 2020 Ó RILEM 2020
Abstract Influence of different drying techniques, namely, vacuum drying, oven drying (40 °C) and D-drying on the composition and microstructure of the calcium sulfoaluminate (CSA) cement was investigated in this study. The vacuum drying and oven drying were performed after the samples were immersed in acetone or ethanol. The results show that D-drying decomposes ettringite (AFt) greatly. Following solvent replacement, oven drying slightly decomposes AFt when compared with the vacuum dried sample, possibly due to the carbonation of AFt in the oven drying process. The decomposition of AFt
due to D-drying and oven drying affects both the compositional and microstructural analysis of CSA hydrates. In addition, the soaking time of the samples in the solvents has no effect on the thermogravic (TG) analysis of the hydration products of CSA cement, which indicates that the CSA cement hydrates have no interaction with the solvents. Keywords Calcium sulfoaluminate cement Ettringite Drying techniques Composition Microstructure
M. Liu J. Ren Guangdong Key Laboratory of Durability in Coastal Civil Engineering, College of Civil Engineering, Shenzhen University, Shenzhen 518060, People’s Republic of China
1 Introduction
M. Liu College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, People’s Republic of China
A wide variety of techniques have been employed to study the composition and microstructure of cementbased materials. However, most of the techniques are preferred to be performed on the dry samples to avoid the influence of water [1–3]. Those techniques include thermogravimetric (TG) analysis, Fourier Transform Infrared (FTIR) Spectrometer, mercury intrusion porosimetry (MIP) etc. In addition, because of the accessibility of instruments, it is common for the samples to be retained for several hours, even days before they can be analysed. If the hydration of the samples were not arrested before the retaining, the composition and microstructure could be altered.
S. Luo (&) L. Yang Henan Key Laboratory of Materials on Deep-Earth Engineering, School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454003, People’s Republic of China e-mail: [email protected] J. Ren School of Science, Harbin Institute of Technology (Shenzhen), Nanshan, Shenzhen 518055, People’s Republic of China
1.1 Background
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Therefore, it is necessary to develop a drying method to arrest the hydration for future analysis. Typically, there are three types of water in the cement hydrates, which are capillary water, gel water and combined water [4]. Capillary water is the water held in the pores in the cement hydrates, and the water can react with the cement minerals o
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