纳米二氧化硅对硅灰复合硬化水泥浆力学性能的影响

Effect of Nano-silica on Mechanical Properties of Silica Fume Composite Hardened Cement Paste

为了研究纳米二氧化硅(NS)对硅灰(SF)复合硬化水泥浆体力学性能的影响,在10%硅灰质量分数的基础上设计了NS掺量分别为质量分数0.5%、1%、2%的样品,并测试了所有样品的抗压强度。此外,利用纳米压痕技术测试了样品的微观力学性能,并利用统计纳米压痕技术分析了NS对水化相的相对含量的影响。结果表明:在2%NS质量分数范围内,NS能提高硅灰复合水泥浆体的28天抗压强度,质量分数2%的NS与硅灰的协同效果最好;相对较高NS质量分数的硬化水泥浆体具有更多高模量和高硬度的区域;随着NS质量分数增加,硬化水泥浆体中以毛细孔为主的LP C-S-H凝胶的含量明显降低,而低密度C-S-H与高密度C-S-H的含量之和大幅增加。

In order to investigate the effect of nano-silica(NS) and silica fume(SF) on the mechanical properties of silica fume composite hardened cement paste, on the basis of 10% silica fume mass fraction, the samples with NS mass fractions of 0.5%, 1% and 2% were designed, and the compressive strength of all specimens was tested. In addition, the micro-mechanical properties of the specimens were tested by the nanoindentation technique, and the influence of NS on the relative content of the hydrated phase was analyzed by the statistical nanoindentation technique.The results showed that in the range of 2% NS mass, NS improved the 28-day compressive strength of silica fume composite hardened cement paste and the synergistic effect of 2% NS and silica fume was the best. The hardened cement paste with relatively higher NS mass fraction had more areas of high modulus and high hardness;With the increase of NS dosage, the content of LP C-S-H gel dominated by capillary pores decreased significantly, while the content of low-density C-S-H and high-density C-S-H increased evidently.