预应力高性能混凝土梁中超细粉煤灰合理掺量研究

对粉煤灰高性能混凝土的早期抗压强度、劈裂抗拉强度、早期弹性模量、钢筋握裹力、抗剪强度和徐变性能,超细粉煤灰的合理掺量和护筋性,高性能混凝土模型梁的疲劳性能等进行试验研究。结果表明:一定掺量的优质粉煤灰可改善混凝土的性能,降低结构的寿命周期成本;铁路预应力梁中超细粉煤灰(UFA)的推荐掺量为25%。6片32mC50超细粉煤灰高性能混凝土试验梁的静载试验结果表明,其各项性能指标满足铁路《桥规》要求。

Study on the Rational Replacement Level of Ultra-fine Fly Ash in Prestressed High Performance Concrete Beam

The influences of ultra-fine fly ash (UFA) on the mechanical properties of high performance concrete (HPC) were studied by experiments, including early compressive strength and splitting tensile strength, early elastic modulus, bond stress of steel, shear strength and creep of HPC containing UFA, the rational content and the protective ability of HPC containing UFA against corrosion of reinforcing steel and fatigue of high performance concrete model girder. Experimental results showed that an appropriate replacement level of UFA could improve concrete properties and lower life-cycle cost of structure. The rational content of UFA in railway prestressed girder, UFA substituting 25 percent of ordinary Portland cement (by mass), is recommended in this paper. The results of the dead-load test of six 32-meter test beams made from C50 HPC containing UFA showed that the beam met the requirements of the Railway Bridge and Culvert Design Code.