Different Chlorides Attack on the Hydration of Calcium Aluminate Cement at 5~40°C

Abstract:

Calcium aluminate cement (CAC) has excellent resistance to seawater erosion, but the mechanism remains to be explored. Effects of NaCl and CaCl₂ on the hydration of CAC at 5, 20 and 40°C were investigated in this paper by X-ray diffraction(XRD), thermal analyzer(TG-DSC), scanning electron microscopy(SEM), acoustic and electroacoustic spectrometer. Results show that the varieties of chlorides have great impacts on the chloride binding ability, mechanical properties and microstructure of cement pastes at different temperatures. At 5°C and 20°C, the formation of C₂AH₈ is suppressed by chloride attack. Though the addition of NaCl promotes the formation of CAH₁₀, CaCl₂ leads to a denser microstructure and the improvement in compressive strength. At 40°C, C₂AH₈ disappears by chloride attack, while C₃AH₆ and Friedel’s salt increase. Comparing with the attack of CaCl₂, NaCl contributes to the formation of C₃AH₆. Therefore, it results in a the retraction in compressive strength, ascribing to a coarser structure. In addition, although NaCl is superior in chemical binding ability, CaCl₂ has better physical adsorption ability which dominants the binding process, and thus leading to greater amount of bonded chloride than that with NaCl. This research provides the oretical basis for the application of CAC in marine environment.

• Periodical: Materials Science Forum (Volume 1036)
• Pages: 247-254
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.1036.247
• Online since: June 2021
• Authors: Zhong Ping Wang, Yu Ting Chen, Xiang Peng, Ling Lin Xu*
• Keywords: Calcium Aluminate Cement, Chloride Attack, Chloride Biding, Hydration, Temperature

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