铝掺杂水化硅酸钙的分子结构和力学性能

Molecular Structure and Mechanical Properties of Aluminum Substituted C-S-H

摘要:

通过试验结合分子动力学，模拟研究了Al掺杂影响水化硅铝酸钙（C-A-S-H）的机理.结果表明：Al掺杂对于C-A-S-H凝胶中硅铝氧链链长的影响可等效为同摩尔量Si的影响，但会使C-A-S-H凝胶层间距增加的幅度更大；提高养护温度促进了C-A-S-H凝胶中硅氧四面体的聚合，当养护温度达到80 ℃时，C-A-S-H凝胶的层间距减小，相邻主层上硅铝氧链之间形成了交联结构，部分转变为交联C-A-S-H凝胶，其力学性能大幅度增加；Al掺杂桥接了断裂的硅氧链且形成了硅铝氧长链，提升了C-A-S-H凝胶沿y轴方向的力学性能，对其沿x轴和z轴方向力学性能的影响较小.

Abstract:

The influence mechanism of Al substitution on the nanostructure and properties of the calcium aluminosilicate hydrate（C-A-S-H） gel was investigated through the combination of experiment and molecular dynamics simulation. The results show that influence of Al on the molecular chain length of the aluminosilicate chain substitution of C-A-S-H gel structure can be considered to be due to the same molar amount of Si， but Al substitution leads to a larger increase in the basal spacing of C-A-S-H gel. Elevated curing temperature promotes the polymerization of the aluminate/silicate tetrahedra in the C-A-S-H gel， resulting in increasing mean chain length of C-A-S-H gel. When the curing temperature reaches up to 80 ℃， the spacing between the C-A-S-H gel primary layers abruptly reduces. Cross-linked structure are formed between the aluminosilicate chains on the adjacent main layer， which indicates parts of C-A-S-H gel are cross-linked. The mechanical properties of cross-linked C-A-S-H gel induced by the aluminum are greatly increased. Substituted Al bridges the broken silicon-oxygen chain. The formation of the long aluminosilicate chain improves the mechanical properties of C-A-S-H gel along the y-axis， but shows negligible effect on its mechanical properties along the x- and z-directions.