The role of aluminium in C-A-S-H during sulfate attack on concrete
The role of aluminium in C-A-S-H during sulfate attack on concrete
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DOI：
10.1016/j.cemconres.2018.11.012
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发表时间：
2019-02-01
影响因子：
11.4
通讯作者：
Heinz, D.
中科院分区：
文献类型：
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作者：
Irbe, L.;Beddoe, R. E.;Heinz, D.
通过C-A-S-H相在Na2SO4溶液(3和30g/L SO4)中的存放试验，研究了混凝土在硫酸盐侵蚀过程中C-A-S-H纳米结构的变化。特别注意了铝在C-A-S-H中形成钙矾石的有效性。钙矾石仅形成于饱和pH以上的孔雀石。C-A-S-H中铝的脱除降低了C-A-S-H相的Al/Si比和平均链长。在低于孔雀石饱和pH的溶液中没有钙矾石生成。在这里，C-A-S-H相的脱钙导致MCL的增加。在Na_2SO_4溶液中，C-A-S-H中铝形成钙矾石的过程受钙的有效性控制。钠被吸附在C-A-S-H的去质子化硅醇基团上。在3g/L SO4时，SO42-与钙吸附在去质子化的硅醇基团上，而在30g/L SO4时，它们还与C-A-S-H中的其他中心成键。
Storage tests with C-A-S-H phases in Na2SO4 solutions (3 and 30 g/L SO4) were carried out to study changes in the C-A-S-H nanostructure during sulfate attack on concrete. Particular attention was paid to the availability of aluminium in C-A-S-H for ettringite formation. Ettringite only formed above the saturation pH of portlandite. The removal of aluminium from C-A-S-H decreased the Al/Si ratio and mean chain length (MCL) of the C-A-S-H phases. No ettringite formed in solutions below the saturation pH of portlandite. Here, decalcification of the C-A-S-H phases resulted in an increase in MCL. The formation of ettringite from aluminium in C-A-S-H exposed to Na2SO4 solutions is controlled by the availability of calcium. Sodium is adsorbed on deprotonated silanol groups in C-A-S-H. At 3 g/L SO4, the SO42- ions are adsorbed with calcium on deprotonated silanol groups, but at 30 g/L SO4, they are also bonded to other sites in C-A-S-H.