Dissolution and initial hydration behavior of tricalcium aluminate in low activity sulfate solutions
Dissolution and initial hydration behavior of tricalcium aluminate in low activity sulfate solutions
复制标题
DOI：
10.1016/j.cemconres.2020.105989
复制
发表时间：
2020-04-01
影响因子：
11.4
通讯作者：
Bullard, Jeffrey W.
中科院分区：
文献类型：
--
作者：
Brand, Alexander S.;Feldman, Steven B.;Bullard, Jeffrey W.
通过原位溶解速率测量、二次离子质谱非原位近表面成分测量和同步辐射X射线衍射原位监测水化产物的析出，研究了碱金属和碱土金属硫酸盐对立方铝酸三钙（C（3）A）水化的影响。观察到溶解速率和与固体的阳离子特异性相互作用均轻微降低。在一些溶解之后，近表面Ca/Al比率显著降低，并且电解质阳离子以不同的亲和力（Mg 2 + > K+ > Na+）结合在表面内。一个界面溶解再沉淀机制可以解释的意见，以及，或更好地比，一个简单的阳离子交换。溶液中硫酸盐浓度影响C（3）A溶解速率和水化产物沉淀速率。硫酸根离子可能吸附在含水富铝表面层，从而降低铝酸盐的溶解速率并延迟铝酸盐水化产物的沉淀。
Influences of alkali or alkaline earth sulfates on the hydration of cubic tricalcium aluminate (C(3)A) 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 C(3)A 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.