Effects of amorphous nano-silica additions on mechanical and durability performance of SCC mixtures
Effects of amorphous nano-silica additions on mechanical and durability performance of SCC mixtures
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发表时间：
2012
影响因子：
11.4
通讯作者：
G. Quercia;P. Spiesz;G. Hüsken;J. Brouwers
中科院分区：
文献类型：
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作者：
G. Quercia;P. Spiesz;G. Hüsken;J. Brouwers
近年来，纳米技术在建筑材料中的应用呈指数级增长。最常提及和使用的纳米材料之一是粒径在纳米范围内的无定形二氧化硅，尽管其在混凝土中的应用和效果尚未完全了解。据报道，纳米二氧化硅 (nS) 的添加可提高抗压强度并降低硬化混凝土的整体渗透性，因为火山灰特性会产生更细的水合相（C-S-H 凝胶）和致密化的微观结构（纳米填料和抗浸出效果）。这些效应增强了海洋环境中桥梁、码头或海上石油设施等混凝土结构的耐用性。在这项研究中，两种不同类型的纳米二氧化硅被应用于自密实混凝土（SCC）中，两者具有相似的粒度分布（PSD），但采用两种不同的工艺生产（成膜粉末二氧化硅和胶体悬浮液中的沉淀二氧化硅）。研究了纳米二氧化硅对混凝土在新鲜状态（和易性）和硬化状态（力学性能和耐久性）下的 SCC 的影响。此外，通过 SEM 和 EDS 分析验证了硬化混凝土微观结构的致密化。所得结果表明，在 SCC 中有效使用纳米二氧化硅可以提高其机械性能和耐久性。考虑到所研究的两种纳米二氧化硅的反应性，胶体类型在早期表现出更多的反应性，这影响了所有最终的 SCC 特性。
In the recent years the application of nanotechnology in building materials has increased exponentially. One of the most referred and used nano-materials is amorphous silica with particles size in the nano-range, even though its application and effect in concrete has not been fully understood yet. It has been reported that nano-silica (nS) addition increases the compressive strength and reduces the overall permeability of hardened concrete due to the pozzolanic properties which are resulting in finer hydrated phases (C-S-H gel) and densified microstructure (nano-filler and anti leaching effects). These effects enhance the durability of concrete structures such as bridges, quays or off-shore oil facilities in marine environments. In this study two different types of nano-silica were applied in self-compacting concrete (SCC), both having similar particle size distributions (PSD) but produced in two different processes (filmed powder silica and precipitated silica in colloidal suspension). The influence of nanosilica on SCC was investigated with respect to the properties of concrete in the fresh state (workability) and hardened state (mechanical properties and durability). Additionally, the densification of microstructure of the hardened concrete was verified by SEM and EDS analyses. The obtained results demonstrate that an efficient use of nano-silica in SCC can improve its mechanical propelties and durability. Considering the reactivity of the two nano-silica studied, colloidal type shown more reactivity at early age, which influenced all the final SCC properties.