Title: Chloride Adsorption of Cement Hydrates Combined with Chemical Evolution of Pore Solution

Author(s): In-Seok Yoon and Tatsuhiko Saeki

Publication: Materials Journal

Volume:

Issue:

Appears on pages(s):

Keywords: chloride adsorption, AFm phase, Friedel’s salt, C-S-H phase, Ca/Si ratio

DOI: 10.14359/51742037

Date: 7/10/2024

Abstract:
In this study, a chloride adsorption test was performed to depict the chemical evolution of pore solution for cement hydration. It was found that the amount of chloride adsorbed by the AFm phase and the C-S-H phase decreased with the increasing pH of the pore solution. The stability of Friedel's salt tended to decrease with the increasing pH of the pore solution. Notably, in the C-S-H phase, the decrease in the amount of chloride adsorption resulting from an increase in the pH level was larger when the Ca/Si ratio was higher. Based on these works, multiple regression analysis was performed to examine the correlation between the chloride adsorption density of cement hydrates and the experimental variables involved, including the pH of the pore solution and the amount of chloride ion penetration. The pH of the pore solution was predicted based on cement hydration and pore chemistry theories, and these results were combined with the experimental results, considering the changing chemical characteristics of the pore solution during each temporal stage of cement hydration. The amount of chloride ion adsorption in FA and GBFS was larger than in OPC due to the decreased pH of the pore solution, resulting from the consumption of calcium hydroxide.