不同因素对UHPC-普通混凝土黏结强度影响的试验研究

Experimental Study on Effects of Different Factors on Bonding Strength Between UHPC and Ordinary Concrete

通过斜剪切与劈裂抗拉试验方法研究了超高性能混凝土(UHPC)与普通混凝土(NC)的黏结性能,分析了UHPC关键组分、不同界面处理方法、普通混凝土强度等级及不同种类界面剂等因素对UHPC-NC黏结强度的影响。研究结果表明,相较于未处理表面,钢丝刷毛、表面切槽和表面凿毛三种界面处理方法分别对C30(C50)基体混凝土与UHPC间的剪切黏结强度提升了32.9%(42.3%)、45.4%(6.5%)、12.8%(15.3%);使用净浆、膨胀剂净浆涂刷黏结界面相较于未处理表面分别对C30 (C50)基体混凝土间的剪切黏结强度提高了10.8%(32.3%)和6.8%(14%),抗拉黏结强度提升规律基本一致,而使用环氧树脂和丁苯净浆作为界面剂会降低UHPC-NC的黏结性能;相比较素UHPC,掺入钢纤维和膨胀剂分别对C30(C50)基体与UHPC间的剪切黏结强度提升了16.4%(32%)和6.8%(11.1%),而掺入PVA纤维几乎无影响。

The bonding properties of ultra-high performance concrete(UHPC) and ordinary concrete(NC) were studied by oblique shearing and splitting tensile test. The effects of UHPC key components, different interface treatment methods, ordinary concrete strength grades and different kinds of interface agents on the bond strength of UHPC-NC were studied. The results show that the shear bond strength of C30(C50) base concrete and UHPC after wire brushing, surface grooving and surface chiseling is increased by 32.9%(42.3%), 45.4%(6.5%), 12.8%(15.3%) respectively, compared with the untreated surface;the shear bond strength of C30(C50) base concrete and UHPC using cement paste, cement paste with expanding agent is increased by 10.8%(32.3), 6.8%(14%), respectively, compared with the untreated surface, as for split tensile strength, the results are similar. While using cement paste with SBR or epoxy will reduce the bonding strength. Compared with the plain UHPC, the shear bond strength of the C30(C50) substrates is increased by 16.4%(32%) and 6.8%(11.1%), respectively, and the incorporation of PVA fibers has almost no effect.