Nanosilica in-situ produced with sodium silicate as a performance enhancing additive for concretes
Nanosilica in-situ produced with sodium silicate as a performance enhancing additive for concretes
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DOI：
10.1016/j.cemconcomp.2023.105198
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发表时间：
2023-09
影响因子：
10.5
通讯作者：
Xin Qian;H. Yang;Jialai Wang;Yi Fang;Liang Wang;Peiyuan Chen;Hongduo Zhao
中科院分区：
文献类型：
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作者：
Xin Qian;H. Yang;Jialai Wang;Yi Fang;Liang Wang;Peiyuan Chen;Hongduo Zhao
本研究建议使用原位生产的纳米二氧化硅来提高水泥砂浆的性能。为此，开发了两步混合方法。在步骤I中，将低成本的硅酸钠和单宁酸（TA）溶液与混合水混合，其中TA可以引发硅酸钠的缩合以产生多孔二氧化硅纳米粒子并将产生的纳米粒子分散在混合水中。然后将所得混合水与纳米二氧化硅直接用于混合水泥砂浆。实验结果表明，采用该方法生产的水泥砂浆28d抗压强度比现有方法生产的水泥砂浆提高了35%。这种强度的提高远远超过了非原位添加纳米二氧化硅所能达到的效果，这可以归因于原位产生的纳米二氧化硅可以显着降低水泥浆体的孔隙率，正如压汞孔隙率测试所揭示的那样。出于同样的原因，所生产的水泥砂浆的抗硫酸盐侵蚀能力也通过所提出的方法得到增强。该方法克服了纳米颗粒在混凝土中应用所面临的所有挑战，例如成本高、分散困难等，适合在混凝土中大规模现场应用。
This study proposes to use an in-situ produced nanosilica to enhance the performance of cement mortar. To this end, a two-step mixing method is developed. In Step I, low-cost sodium silicate and tannic acid (TA) solutions are mixed with the mixing water, in which TA can trigger the condensation of sodium silicate to produce porous silica nanoparticles and disperse the produced nanoparticles in the mixing water. The resulting mixing water with nanosilica is then directly used to mix cement mortar. Experimental results show that the compressive strength at 28d of the cement mortar produced by the proposed method is 35% higher than the one produced using the existing method. This strength improvement far exceeds what can be achieved by the ex-situ addition of nanosilica, which can be attributed to the fact that the in-situ produced nanosilica can significantly reduce the porosity of the cement paste, as revealed by the mercury intrusion porosimetry test. For the same reason, the produced cement mortar's resistance to sulfate attack is also enhanced by the proposed method. The proposed method is ready for large-scale field application in concrete since it overcomes all challenges facing the utilization of nanoparticles in concretes, such as high cost and difficult dispersion.