Influence of nano-silica agglomeration on microstructure and properties of the hardened cement-based materials
Influence of nano-silica agglomeration on microstructure and properties of the hardened cement-based materials
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DOI：
10.1016/j.conbuildmat.2012.08.006
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发表时间：
2012-12-01
影响因子：
7.4
通讯作者：
Shah, Surendra P.
中科院分区：
文献类型：
--
作者：
Kong, Deyu;Du, Xiangfei;Shah, Surendra P.
以凝聚体较大的沉淀硅(PS)和凝聚体较小的气相二氧化硅(FS)为纳米级外加剂，研究了纳米二氧化硅团聚对水泥基硬化材料微观结构和性能的影响。结果表明，PS或FS的加入均能细化水泥浆体的孔结构。然而，扫描电子显微镜观察表明，凝聚体中的火山灰C-S-H凝胶不能起到粘结剂的作用。在凝聚体和块体浆体之间甚至存在界面过渡区。纳米压痕试验表明，大颗粒颗粒由于强度和弹性模数较低，有可能成为弱区。认为微观结构的改善与播种效应无关，而是吸水、充填和火山灰效应的结果。通过PS的掺入，提高了砂浆的抗压强度，提高了砂浆的抗钙、抗氯离子渗透性能。然而，这些改善幅度较小。比添加FS的显著。这是因为掺加FS的砂浆比掺PS的砂浆提供的填料要多得多，而引入的薄弱带却少得多。(C)2012爱思唯尔有限公司。保留所有权利。
Influence of nano-silica agglomeration on microstructure and properties of the hardened cement-based materials was investigated by using precipitated silica (PS) with very large agglomerates and fumed silica (FS) with much smaller ones as nanoscale additives. The results showed that the addition of either PS or FS refines pore structure of the hardened cement paste. However, the SEM observation revealed that the pozzolanic C-S-H gels from the agglomerates cannot function as binder. There even exists interfacial transition zone between the agglomerates and the bulk paste. The nano-indentation test indicated that the large agglomerates may become weak zones due to their low strength and elastic modulus. It is proposed that the microstructure improvement have nothing to do with the seeding effect, but result from the water-absorbing, filling, and pozzolanic effects. Through PS addition, compressive strength of the mortars and their resistance to calcium leaching and chloride penetration were enhanced. However, these improvements were less. significant than those with FS addition. The reason is that much more fillers are provided whereas much fewer weak zones are introduced in the mortar with FS addition than that with PS. (C) 2012 Elsevier Ltd. All rights reserved.