Effect of Calcium Silicate Sources on Geopolymerisation
Effect of Calcium Silicate Sources on Geopolymerisation
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DOI：
10.1016/j.cemconres.2007.11.001
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发表时间：
2008-04
影响因子：
11.4
通讯作者：
Christina K. Yip;G. C. Lukey;J. Provis;J. Deventer
中科院分区：
文献类型：
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作者：
Christina K. Yip;G. C. Lukey;J. Provis;J. Deventer
七种不同的硅酸钙材料被用来研究钙在地质聚合中的作用。在低碱度下，主要用无定形硅酸钙（高炉矿渣）制备或含有专门为反应性制造的结晶相（水泥）的基质的抗压强度比钙作为结晶硅酸盐矿物供应时高得多。含有天然（结晶）硅酸钙的基质的抗压强度随着碱度的增加而提高，然而在用加工的硅酸钙源合成的基质中观察到相反的趋势。在高碱度下，使用不同硅酸钙源合成的基质之间的抗压强度差异显著减小。在相对低的碱度下，不足量的钙从结晶硅酸钙中溶解，从而能够形成与铝硅酸盐地质聚合物凝胶共存的硅酸钙水合物，这导致这种基质的机械性能差。在高碱度下，钙在影响最终粘合剂的性质方面起的作用较小，因为它形成沉淀物而不是水合凝胶。因此，不同的硅酸钙源不会对这些基质的机械性能产生重大影响。因此，不同的硅酸钙对地质聚合的影响最显著地取决于两个因素：硅酸钙源的结晶度和所用活化溶液的碱度。
Seven different calcium silicate materials were used to investigate the role of calcium in geopolymerisation. At low alkalinity, the compressive strength of matrices prepared with predominantly amorphous calcium silicates (blast furnace slag) or containing crystalline phases specifically manufactured for reactivity (cement) is much higher than when the calcium is supplied as crystalline silicate minerals. The compressive strength of matrices containing natural (crystalline) calcium silicates improves with increasing alkalinity, however the opposite trend is observed in matrices synthesised with processed calcium silicate sources. The difference in compressive strength between matrices synthesised using different calcium silicate sources is significantly reduced at high alkalinity. An insufficient amount of calcium is dissolved from crystalline calcium silicates at relatively low alkalinity to enable formation of calcium silicate hydrate in coexistence with the aluminosilicate geopolymeric gel, and this leads to the poor mechanical properties of such matrices. At high alkalinity, calcium plays a lesser role in affecting the nature of the final binder, as it forms precipitates rather than hydrated gels. Thus, the different calcium silicate sources will not have a major impact on the mechanical properties of these matrices. The effects of different calcium silicates on geopolymerisation are therefore seen to depend most significantly on two factors: the crystallinity of the calcium silicate source, and the alkalinity of the activating solution used.