To investigate the influence of hybrid effect of different sizes of polypropylene fibers (PPFs) on the compressive constitutive mechanical parameters of roller compacted concrete, nine groups of fiber reinforced concrete specimens containing different sizes of PPFs were designed and the uniaxial compressive testing was conducted. Based on the existing compressive constitutive model and the test stress–strain curves, the peak stress, peak strain, elastic modulus, and the post-peak stage parameter with different fiber proportion were analyzed and discussed to find the optimum mixing proportion of different sizes of PPF, the calculation of compressive toughness factor were given. The results showed that the addition of PPF could improve the compressive properties of RCC. The axial compressive strength and compressive strain of RCC increased by 3%~16% and 7%~57%, respectively. Meanwhile, the coarse PPF can significantly enhance the ductility of RCC when subjected to uniaxial compressive loading, and the group of multi-scale PPF hybridization had higher compressive toughness than groups blended with two types of PPF, showing a more obvious positive hybrid effect. Finally, multi-scale fiber hybrid effect function was proposed, the results showed that the function can well reflect the influence of fiber hybrid effect on the compressive properties of RCC and can be used to predict the optimal fiber proportion of fiber reinforced concrete.

中文翻译：

---

多尺度聚丙烯纤维杂化对碾压混凝土抗压本构力学参数的影响

为研究不同尺寸聚丙烯纤维（PPFs）的混合效应对碾压混凝土抗压本构力学参数的影响，设计了9组含有不同尺寸PPFs的纤维增强混凝土试件并进行了单轴抗压试验。基于已有的压缩本构模型和试验应力-应变曲线，对不同纤维配比下的峰值应力、峰值应变、弹性模量和峰后阶段参数进行分析讨论，找出不同尺寸纤维的最佳混合比例。给出了PPF、抗压韧性系数的计算方法。结果表明，PPF的加入可以提高碾压混凝土的抗压性能。碾压混凝土的轴向抗压强度和抗压应变分别提高了3%~16%和7%~57%。同时，粗化PPF可以显着提高RCC在单轴压缩载荷下的延展性，多尺度PPF杂化组的抗压韧性高于两种PPF共混组，表现出更明显的正杂化效果。最后，提出了多尺度纤维混合效应函数，结果表明该函数能很好地反映纤维混合效应对碾压混凝土抗压性能的影响，可用于预测纤维增强混凝土的最佳纤维配比。且多尺度PPF杂化组的抗压韧性高于两种PPF共混组，表现出更明显的正杂化效果。最后，提出了多尺度纤维混合效应函数，结果表明该函数能很好地反映纤维混合效应对碾压混凝土抗压性能的影响，可用于预测纤维增强混凝土的最佳纤维配比。且多尺度PPF杂化组的抗压韧性高于两种PPF共混组，表现出更明显的正杂化效果。最后，提出了多尺度纤维混合效应函数，结果表明该函数能很好地反映纤维混合效应对碾压混凝土抗压性能的影响，可用于预测纤维增强混凝土的最佳纤维配比。