Dam concrete suffers from serious abrasion damages in southwestern China, the abrasion resistance of concrete is therefore one of the most important factors determining the reliability even the safety of the dams. In the present work, the effects of fly and/or silica fume on the mechanical properties, drying shrinkage, as well the cracking and abrasion resistance of concrete were investigated, then the pore structures of concrete added with fly ash and silica fume and the pore surface fractal dimensions (Ds) were determined by the mercury intrusion porosimetry (MIP) method and a fractal model, respectively. Finally, the relationships between the abrasion resistance of concrete and the porosity as well as the Ds were revealed and discussed. The results indicate that silica fume significantly increases the drying shrinkage especially at early age, while the incorporation of fly ash and silica fume together can decrease the early plastic shrinkage-induced cracking risk and the final shrinkage to some degrees. Besides, the utilization of 5wt.% silica fume and 20wt.% fly ash together increases the abrasion resistance and mechanical property by about 4–9% at various ages. In addition, the compressive strength and the abrasion resistance of concrete are linearly correlated with the concrete porosity and the Ds. Both the fly ash and silica fume could decrease the porosity of concrete and increase the Ds, therefore the concrete containing fly ash and silica fume have desired mechanical property and abrasion resistance. Moreover, Ds has a more profound effect on the abrasion resistance of concrete than the concrete porosity. The addition of 5wt.% silica fume and 20wt.% fly ash together is suitable for the concretes used for wearing surfaces in terms of mechanical property, cracking and abrasion resistance.

中文翻译：

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粉煤灰和硅灰对混凝土力学性能和耐磨性影响的孔隙结构和分形分析

我国西南地区大坝混凝土磨损严重，因此混凝土的耐磨性是决定大坝可靠性乃至安全性的最重要因素之一。在目前的工作中，研究了飞灰和/或硅灰对混凝土的力学性能、干缩以及抗裂和耐磨性的影响，然后研究了添加粉煤灰和硅灰的混凝土的孔隙结构和孔隙表面分形维数 (Ds) 分别通过压汞法 (MIP) 和分形模型确定。最后，混凝土的耐磨性与孔隙率之间的关系以及Ds被揭露和讨论。结果表明，硅灰显着增加了干燥收缩率，特别是在早期，而粉煤灰和硅灰的混合可以在一定程度上降低早期塑性收缩引起的开裂风险和最终收缩率。此外，利用 5wt.% 硅灰和 20wt.% 的粉煤灰在不同年龄下共同增加了约 4-9% 的耐磨性和机械性能。此外，混凝土的抗压强度和耐磨性与混凝土的孔隙率和耐磨性呈线性相关。Ds. 粉煤灰和硅灰都能降低混凝土的孔隙率，增加混凝土的孔隙率。Ds，因此含有粉煤灰和硅灰的混凝土具有所需的力学性能和耐磨性。而且，Ds比混凝土孔隙率对混凝土耐磨性的影响更为深远。增加 5wt.% 硅灰和 20wt.%粉煤灰在力学性能、抗裂性和耐磨性方面适用于耐磨面的混凝土。