粗骨料粒径和硅灰对混凝土断裂性能影响的试验研究

Experimental study on the effects of aggregate size and silica fume on the fracture property of concrete

应用双参数模型确定混凝土在不同粗骨料粒径和不同硅灰掺量时的临界应力强度因子(K_(1c)^(?))和临界裂缝尖端张开位移(CTOD_c),同时利用特征长度l^(ch)研究粗骨料粒径和硅灰掺量对混凝土脆性的影响。文章也给出了相应的弹性模量、抗压强度以及抗拉强度。试验龄期为28天。试验结果表明,对于高强混凝土最大粗骨料粒径增大,弹性模量和抗压强度减小,而抗拉强度和临界应力强度因子以及材料的脆性增大;对于中等强度混凝土(MSC),硅灰掺量为10％(硅灰/[硅灰+水泥])的混凝土(MSC-SF)的弹性模量、抗压强度、抗拉强度、临界应力强度因子和脆性都大于不掺硅灰的MSC。

Two-parameter model was applied to determine the critical stress intensity factor K_(Ic)~s and critical crack tip opening displacement CTOD_c of concrete with different coarse aggregate sizes and silica fume dosages. The characteristic length l_(ch) was used to evaluate the effects of coarse aggregate size and silica fume dosage on the brittleness of concrete. All specimens were tested at 28 days. The test results show that, for high strength concrete, the compressive strength and elastic modulus increase with decreased maximum coarse aggregate size, but the splitting tensile strength, critical stress intensity factor and brittleness varied in the opposite sense. The compressive strength, splitting tensile strength, elastic modulus and critical stress intensity factor of MSC2(containing 10% silica fume)is higher than MSC1(without silica fume), but MSC2 is more brittle than MSC1.