Effect of nano-silica on the hydration and microstructure development of Ultra-High Performance Concrete (UHPC) with a low binder amount
Effect of nano-silica on the hydration and microstructure development of Ultra-High Performance Concrete (UHPC) with a low binder amount
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DOI：
10.1016/j.conbuildmat.2014.04.063
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发表时间：
2014-08-29
影响因子：
7.4
通讯作者：
Brouwers, H. J. H.
中科院分区：
文献类型：
--
作者：
Yu, R.;Spiesz, P.;Brouwers, H. J. H.
研究了纳米SiO2对低胶凝材料超高性能混凝土水化及微观结构的影响。UHPC的设计是基于修改后的Andreasen和Andersen颗粒堆积模型。结果表明，利用该堆积模型，可以在较低的胶凝材料用量（约440 kg/m3）下获得致密均匀的UHPC骨架。此外，由于在本研究中用于生产UHPC的高效减水剂的量高，水泥水化的休眠期延长。然而，由于纳米二氧化硅的成核作用，高效减水剂的延迟效应可以被显著地补偿。此外，随着纳米二氧化硅的加入，UHPC的粘度显著增加，这导致更多的空气被截留在新鲜混合物中，硬化混凝土的孔隙率相应地增加。相反，由于纳米SiO2的成核作用，可以促进水泥的水化，生成更多的C-S-H凝胶。因此，可以得出结论，存在用于生产具有最低孔隙率的UHPC的最佳纳米二氧化硅量，在该最佳纳米二氧化硅量下，可以很好地平衡成核的积极影响和截留空气的负面影响。(C)2014爱思唯尔有限公司版权所有。
This paper presents the effect of nano-silica on the hydration and microstructure development of Ultra-High Performance Concrete (UHPC) with a low binder amount. The design of UHPC is based on the modified Andreasen and Andersen particle packing model. The results reveal that by utilizing this packing model, a dense and homogeneous skeleton of UHPC can be obtained with a relatively low binder amount (about 440 kg/m(3)). Moreover, due to the high amount of superplasticizer utilized to produce UHPC in this study, the dormant period of the cement hydration is extended. However, due to the nucleation effect of nano-silica, the retardation effect from superplasticizer can be significantly compensated. Additionally, with the addition of nano-silica, the viscosity of UHPC significantly increases, which causes that more air is entrapped in the fresh mixtures and the porosity of the hardened concrete correspondingly increases. In contrary, due to the nucleation effect of nano-silica, the hydration of cement can be promoted and more C-S-H gel can be generated. Hence, it can be concluded that there is an optimal nano-silica amount for the production of UHPC with the lowest porosity, at which the positive effect of the nucleation and the negative influence of the entrapped air can be well balanced. (C) 2014 Elsevier Ltd. All rights reserved.