Preliminary study of the setting of cement paste by impedance measurements
Xinying Lu1*, Chul-Woo Chung2, Leslie J. Struble2
1Graduate School at Shenzhen, Tsinghua University, The University Town, Xili, Shenzhen 518055, P.R. China
2Dept. of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 N. Mathews, Urbana IL 61801-2352
The setting time of cement paste is monitored by impedance measurements using an LCR meter at about 1 kHz. It is found that the capacitance data is more sensitive than resistance or inductance to the gradual changes at the early stages of cement hydration. The turning points are analyzed through experiments using aqueous and non-aqueous cement slurries as well as some other powder materials and through comparison with penetration resistance and ultrasonic wave reflection. The current proposed mechanism for cement paste is that the setting process of cement involves combined physical and chemical processes, that sedimentation and hydration of cement particles are going on simultaneously and continuously in the very early stages of cement hydration, and that there is no obvious manifestation of a dormant period .
Keywords: cement hydration, setting, impedance, sedimentation
* Corresponding author. E-mail: luxy@tsinghua.edu.cn