Fe-rich cementitious phases, such as tetracalcium aluminate (C4AF), are likely the least characterized and understood components of ordinary cements, in terms of their reactivity and early-age reactions. In this study, we provided the first in-situ measurements of C4AF's absolute dissolution rates in water and aqueous sulfate solutions (Na2SO4, MgSO4 and CaSO4) along with its early-age hydration characterization. Upon contact with water, C4AF dissolved at a rate of 1.74 ± 0.23 μmol·m−2·s−1, and sulfates were found to inhibit its reaction. Among the three types of sulfates tested, CaSO4 exhibited the strongest inhibition effect, while Na2SO4 showed the weakest inhibition. Soon after the initial dissolution, the precipitation of hydrates occurred, and the presence of sulfates affected the overall hydration process of C4AF. These results enhance our understanding of C4AF's dissolution and early-age hydration behaviours, thereby advancing our knowledge of its hydration mechanisms.

中文翻译：

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四钙铝铁矿 （C4AF） 在水和硫酸盐水溶液中的溶解和早期水合


富铁胶凝相，如铝酸四钙 （C4AF），就其反应性和早期反应而言，可能是普通水泥中最不具有特征和了解的成分。在这项研究中，我们首次提供了 C4AF 在水和硫酸盐水溶液 （Na2SO4 、 MgSO4 和 CaSO4） 中的绝对溶解速率的原位测量及其早期水合表征。与水接触后，C4AF 以 1.74 ± 0.23 μmol·m-2·s-1 的溶解速率溶解，发现硫酸盐抑制其反应。在供试的 3 种硫酸盐中，CaSO4 表现出最强的抑制作用，而 Na2SO4 表现出最弱的抑制作用。初始溶解后不久，水合物沉淀发生，硫酸盐的存在影响了 C4AF 的整体水合过程。这些结果增强了我们对 C4AF 溶解和早期水合作用行为的理解，从而促进了我们对其水合作用机制的了解。