Fibrillar calcium silicate hydrate seeds from hydrated tricalcium silicate lower cement demand
Fibrillar calcium silicate hydrate seeds from hydrated tricalcium silicate lower cement demand
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DOI：
10.1016/j.cemconres.2020.106195
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发表时间：
2020-11-01
影响因子：
11.4
通讯作者：
Monteiro, Paulo J. M.
中科院分区：
文献类型：
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作者：
Li, Jiaqi;Zhang, Wenxin;Monteiro, Paulo J. M.
关于 C-S-H 籽糊的影响因素和长期性能仍存在争议。在本研究中，通过稀释的 Ca3SiO5 水合制备相纯种子。使用基于同步加速器的 X 射线衍射、X 射线吸收光谱和透射电子显微镜测定种子结构。不同Ca/Si的种子中存在纳米箔和类似的Ca和O环境；纳米纤维仅存在于高钙种子中，其表现出较低的硅酸盐聚合。热量测定和凝结结果显示，高钙种子的水合作用加速更快；种子形状主导了加速度。 0.5 wt% 高钙种子使 1 天和 28 天的糊体强度分别增加 300% 和 20%。生命周期评估显示种子对糊生产的能源需求和二氧化碳排放的影响可以忽略不计（< 1%）。 28 天时，按种子糊强度标准化的 CO2 强度下降了约 25%。这项研究揭示了利用废弃混凝土和洗涤水中的 C-S-H 晶种作为降低水泥需求的一种手段。
Debates remain on the influencing factor and long-term performance of C-S-H-seeded paste. In this study, phase-pure seeds were prepared from diluted Ca3SiO5 hydration. The seed structures were determined using synchrotron-based X-ray diffraction, X-ray absorption spectroscopy, and transmission electron microscopy. Nanofoils and similar Ca and O environments were present in seeds of different Ca/Si; nanofibers were present in high-Ca seeds only which showed lower silicate polymerization. Calorimetry and setting results showed a greater hydration acceleration with high-Ca seeds; seed shape dominated the acceleration. 0.5 wt% high-Ca seeds increased 1- and 28-days paste strength by 300% and 20%, respectively. Life-cycle assessment showed negligible (< 1%) influence of seeds on energy demand and CO2 emissions of the paste production. The CO2-intensity normalized by strength of seeded pastes decreases by similar to 25% at 28 days. This study sheds light on the use of C-S-H seeds from waste concrete and wash water, as a means of lowering cement demand.