Does synthesized C-S-H seed promote nucleation in alkali activated fly ash-slag geopolymer binder?
Does synthesized C-S-H seed promote nucleation in alkali activated fly ash-slag geopolymer binder?
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DOI：
10.1617/s11527-019-1368-3
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发表时间：
2019-08-01
影响因子：
3.8
通讯作者：
Mondal, Paramita
中科院分区：
文献类型：
--
作者：
Puligilla, Sravanthi;Chen, Xu;Mondal, Paramita
了解成核晶种对碱活化粘结剂（AAB）反应动力学和微观结构的影响非常重要，因为这将有助于我们控制早期和长期性能。例如，在含钙AAB中，其他人已经提出水合硅酸钙/水合铝硅酸钙（C-S-H/C-A-S-H）晶种充当成核位点以促进地质聚合物凝胶的形成。在这项研究中，我们研究了通过将合成的C-S-H和C-A-S-H种子添加到由氢氧化钾和硅酸钾溶液活化的F类飞灰-矿渣混合物中的成核效应。从量热法和超声波反射测试，我们发现接种，以加速反应的氢氧化物活化的粘合剂，但减速的硅酸盐活化的粘合剂。基于进一步的化学处理和傅里叶变换红外光谱表征，我们发现氢氧化物粘合剂中的加速是由于C-S-H/C-A-S-H的形成增强，而硅酸盐粘合剂中的减速是由于K-A-S-H凝胶的形成减少，尽管C-S-H/C-A-S-H的形成增强。此外，在这两种类型的粘合剂，我们发现粉煤灰前体的溶解增强。本研究中的证据表明，C-S-H晶种作为进一步沉淀C-S-H/C-A-S-H的成核位点，但不用于形成地质聚合物凝胶。
Understanding the effects of nucleation seeds on reaction kinetics and microstructures of alkali activated binders (AABs) is important since it will help us control both early-age and long-term properties. For example, in the calcium-containing AABs, calcium silicate hydrate/calcium aluminosilicate hydrate (C-S-H/C-A-S-H) seeds have been proposed by others to act as nucleation sites to promote formation of geopolymer gel. In this study, we examined the nucleation effects by adding synthesized C-S-H and C-A-S-H seeds into class F fly ash-slag mixes activated both by potassium hydroxide and by potassium silicate solutions. From both calorimetry and ultrasonic wave reflection tests, we found seeding to accelerate reaction of the hydroxide activated binder but decelerate that of the silicate activated binder. Based on further chemical treatments and Fourier-transform infrared spectroscopic characterization, we found the acceleration in the hydroxide binder was due to enhanced formation of C-S-H/C-A-S-H, while the deceleration in the silicate binder was due to decreased formation of K-A-S-H gel despite the enhanced formation of C-S-H/C-A-S-H. Additionally, in both types of binders, we found dissolution of fly ash precursor was enhanced. Evidence in this study suggests that C-S-H seeds act as nucleation sites for further precipitation of C-S-H/C-A-S-H but not for formation of geopolymer gel.