硅灰对超高性能混凝土性能提升机理试验研究

Experimental Study on Performance Improvement Mechanism of Silica Fume on Ultra-high Performance Concrete(UHPC)

研究了不同硅灰掺量对超高性能混凝土(UHPC)拌合物性能、力学性能的影响,并通过水化程度、孔结构、界面黏结强度等测试方法探讨了硅灰对UHPC性能的提升机理。结果表明,掺入硅灰可从微观和细观层面促进水泥水化、优化孔结构、提升钢纤维与基体的黏结性能,从而提升UHPC的力学性能。当硅灰掺量在20%范围内时,提升效果随着硅灰掺量的增加而增大;当硅灰掺量超过20%时,硅灰的高需水量特性开始显现,使得UHPC拌合物的黏度大幅增加,不利于浇筑成型和气泡排出,使UHPC内部缺陷增多导致其抗压强度下降;硅灰在UHPC中的推荐掺量为10%~20%。

The effects of different silica fume content on the mixture properties and mechanical properties of ultra-high performance concrete(UHPC)were studied,and the improvement mechanism of silica fume on the properties of UHPC was analyzed by testing methods such as hydration degree,pore structure and interfacial bond strength.The results show that the addition of silica fume can promote the hydration of cement in UHPC,optimize the pore structure,and improve the bonding performance between steel fiber and matrix,so as to improve the mechanical properties of UHPC.The improvement effect increases with the increase of silica fume content in the range of 20%.When the silica fume content is over 20%,the characteristics of high water demand of silica fume begins to appear.The viscosity of UHPC mixture increases greatly,which is not conducive to pouring molding and pore discharge.The increase of internal defects leads to the decrease of compressive strength.The recommended content of silica fume in UHPC is 10%~20%.