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Dissolution and initial hydration behavior of tricalcium aluminate in low activity sulfate solutions
Cement and Concrete Research ( IF 10.9 ) Pub Date : 2020-04-01 , DOI: 10.1016/j.cemconres.2020.105989
Alexander S. Brand , Steven B. Feldman , Paul E. Stutzman , Anton V. Ievlev , Matthias Lorenz , Darren C. Pagan , Sriramya Nair , Justin M. Gorham , Jeffrey W. Bullard

Abstract Influences of alkali or alkaline earth sulfates on the hydration of cubic tricalcium aluminate (C3A) were evaluated by in situ dissolution rate measurements, by ex situ near-surface composition measurements with secondary ion mass spectrometry, and by in situ synchrotron X-ray diffraction to monitor precipitation of hydration products. Both slight reductions in dissolution rate and cation-specific interactions with the solid were observed. The near-surface Ca/Al ratio is significantly lower after some dissolution and the electrolyte cations are incorporated within the surface with different affinities (Mg2+ > K+ > Na+). An interfacial dissolution-reprecipitation mechanism may explain the observations as well as, or better than, a simple cation exchange. The sulfate concentration in solution affects the rates of both C3A dissolution and precipitation of hydration products. Sulfate ions likely adsorb at the hydrous Al-rich surface layer, thereby reducing the dissolution rate of aluminates and delaying the precipitation of aluminate hydration products.

中文翻译:

铝酸三钙在低活性硫酸盐溶液中的溶解和初始水化行为

摘要 碱金属或碱土金属硫酸盐对立方铝酸三钙 (C3A) 水合的影响通过原位溶解速率测量、二次离子质谱的非原位近地表成分测量和原位同步加速器 X 射线衍射进行评估。监测水合产物的沉淀。观察到溶解速率和与固体的特定阳离子相互作用的轻微降低。一些溶解后近表面的 Ca/Al 比显着降低,并且电解质阳离子以不同的亲和力结合在表面内(Mg2+ > K+ > Na+)。界面溶解-再沉淀机制可以解释这些观察结果,甚至比简单的阳离子交换更好。溶液中的硫酸盐浓度影响 C3A 溶解和水合产物沉淀的速率。硫酸根离子可能吸附在含水的富铝表面层,从而降低铝酸盐的溶解速率并延迟铝酸盐水合产物的沉淀。
更新日期:2020-04-01
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