Traces of CH in a C4A3$-C2S hydration system. (10th February 2019)

• Record Type: Journal Article
• Authors: Chang, Jun; Li, Jiye; Han, Junnan; Zhang, Tingting
• Is Part Of: Construction & building materials. Volume 197(2019)
• Page Start: 641
• Page End: 651
• Publication Date: 2019-02-10
• Subjects: Traces of CH -- C4A3$-C2S hydration system -- RQPA -- Hydration products -- Hydration process; Shorthand cement oxide notation utilized: C = CaO, A = Al2O3, S = SiO2, $ = SO3, and H = H2O; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2018.11.226
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Traces of CH in the C4 A3 $-C2 S system were characterized using XRD, TG, FTIR, and pH. The RQPA method was used to determine the compositions of the C4 A3 $-C2 S hydration. The hydration process and evolution of the C4 A3 $-C2 S system were investigated. Abstract: A C4 A3 $-C2 S (ye'elimite-belite) clinker system with different C2 S and C4 A3 $ contents is synthesized from analytical reagents and a C4 A3 $-C2 S hydration system is established with a water-cement ratio of 0.4. The traces of calcium hydroxide or portlandite (CH) in the C4 A3 $-C2 S hydration system were characterized using X-ray diffraction (XRD), thermo-gravimetric (TG) analysis, Fourier transform infrared (FTIR) spectroscopy and pH tests. The Rietveld quantitative phase analysis (RQPA) method was used to determine the compositions of the C4 A3 $-C2 S hydration products. The hydration process and microstructure evolution of the system were also investigated. The hydration of the C4 A3 $-C2 S involves two key process: one the consumption of AH3 phase and another the generation and stabilization of CH phase. The occurrence of the CH traces in C4 A3 $-C2 S hydration system can be described in terms of the changes in the C2 S content and the curing age. When the C2 S content is less than 55 wt%, the newly generated AH3 preferentially reacts with the C2 S to generate C2 ASH8 . When the content of C2 S is between 55 wt% and 85 wt%, the C2 S begins direct hydration but the generated CH is immediately consumed by the C2 ASH8 . When the C2 S content is higher than 85 wt%, the CH generated by the hydration of C2 S becomes stable in the C4 A3 $-C2 S hydration system.