塑性混凝土弯拉性能

Flexural tensile properties of plastic concrete

本文基于塑性混凝土弯拉试验,系统研究纤维类型和掺量、硅灰和粉煤灰掺量等对塑性混凝土弯拉强度、峰值挠度和韧性的影响。研究结果表明,掺入塑性混凝土中的纤维、粉煤灰和硅灰起到了增强和增韧作用,使塑性混凝土弯拉强度、峰值挠度和弯拉荷载-挠度曲线的下包面积均有不同程度的增加。随纤维掺量的增加,塑性混凝土弯拉强度、峰值挠度和弯拉荷载-挠度曲线的下包面积均呈现以纤维掺量为0.9 kg/m3时达到最大的先增加后减小的趋势,峰值割线模量有不同程度降低,纤维掺量0.9 kg/m3时峰值割线模量的降幅最大;随粉煤灰掺量在一定范围内的增大,塑性混凝土弯拉强度、峰值挠度和弯拉荷载-挠度曲线的下包面积均有不同程度提高,峰值割线模量有所降低;随硅灰掺量的增加,塑性混凝土弯拉强度显著增大,峰值挠度、弯拉荷载-挠度曲线的下包面积以及峰值割线模量均有不同程度的增加,但荷载-挠度曲线的捏缩现象明显。在此基础上,建立了塑性混凝土弯拉荷载-挠度曲线和韧性的计算公式。

This paper presents a systematic study of flexural tensile tests on flexural tensile strength, mid-span deflection at peak load, and toughness of plastic concrete, influenced by fiber type, fiber content, fly ash content, and silica fume content. The results indicate that flexural tensile strength and deformation properties could be improved to some extent by adding fibers, fly ash or silica fume into the plastic concrete. With fiber content increasing up to 0.9 kg/m3, all the flexural tensile strength, peak load midspan deflection, and area under flexural tensile load-deflection curve were increased, while these three parameters decreased when the content exceeded 0.9 kg/m3. The secant modulus at peak load was reduced to different degrees with different fiber contents, and reached the minimum at the content of 0.9 kg/m3. Adding fly ash within some content increased all the three parameters and reduced the secant modulus at peak load. With an increase in silica fume content, all the three parameters were increased, but a pinch phenomenon became obvious in the load-deflection curve. By analysis on the test results, we formulated a new formula for calculation of toughness and an equation of load-deflection curve.