Phase evolution and mechanical-hydroscopic properties of alkali-silica reaction gels modified by magnesium nitrate
Phase evolution and mechanical-hydroscopic properties of alkali-silica reaction gels modified by magnesium nitrate
复制标题
DOI：
10.1016/j.cemconcomp.2023.105283
复制
发表时间：
2023-11
影响因子：
10.5
通讯作者：
A. Sinha;Jianqiang Wei
中科院分区：
文献类型：
--
作者：
A. Sinha;Jianqiang Wei
碱-硅反应（ASR）的破坏性取决于ASR产物的组成和性质，而将这些吸湿膨胀的凝胶状产物转化为无害相的方法尚未开发。在这项研究中，硝酸镁的ASR凝胶的相的演变，分子结构，吸湿性和力学性能的变化与不同的Mg/Si比从0.1到1.1的影响进行了研究。结果表明，随着Mg/Si比的增加和pH值的降低，ASR产物的主晶相托贝莫石型水化硅酸钙（C-S-H）和碱金属钾霞石被抑制为水镁石，并最终转化为水化镁硅酸盐（M-S-H），ASR产物Q3位的Si-O-Si桥键和Si-O对称伸缩被抑制。相和结构的改变导致吸湿膨胀降低93.5%，强度降低94.7%，弹性模量降低152.3%，使ASR产品的破坏性降低。
Alkali-silica reaction (ASR)'s destructiveness is governed by the compositions and properties of ASR products, while methods of converting these hygroscopic-expansive gel-like products into innocuous phases remain unexploited. In this study, the influence of magnesium nitrate on the evolutions of phase, molecular structure, hydroscopic and mechanical properties of ASR gels with varying Mg/Si ratios from 0.1 to 1.1 was investigated. The results indicate that the primary phases of ASR products, tobermorite-type calcium silicate hydrate (C–S–H) and alkali kanemites, can be suppressed into brucite and eventually converted into magnesium-silicate-hydrate (M-S-H) in the presence of increasing Mg/Si ratios and the consequent decreasing pH. The Si–O–Si bridging bonds and Si–O symmetric stretching in the Q3sites of ASR products can be suppressed. The phase and structure modifications resulted in a 93.5% reduction in hydroscopic swelling, a 94.7% decrease in strength, and a 152.3% drop in modulus of elasticity rendering the ASR products less destructive.