聚丙烯纤维水泥稳定碎石的断裂能试验研究

Experimental Investigation into Fracture Energy of Cement-Stabilized Macadam Reinforced with Polypropylene Fibers

为了研究聚丙烯纤维对水泥稳定碎石断裂韧性的影响，通过聚丙烯纤维水泥稳定碎石和普通水泥稳定碎石的三点弯曲试件断裂试验，测得了试件的断裂能、裂缝嘴张开位移和裂缝尖端张开位移，给出了聚丙烯纤维体积掺量的合理范围——0．6‰～0．8‰。试验结果表明：聚丙烯纤维可以明显提高水泥稳定碎石的断裂能、极限裂缝嘴张开位移和极限裂缝尖端张开位移；随着试验龄期的增长，无论聚丙烯纤维掺入与否，水泥稳定碎石的断裂能均呈增大趋势；随着纤维体积掺量的增加，水泥稳定碎石的断裂能、极限裂缝嘴张开位移和极限裂缝尖端张开位移逐渐增大；随水泥掺量的增加，聚丙烯纤维水泥稳定碎石试件的极限荷载逐渐增加，但断裂能却逐渐减小．

In order to reveal the effect of polypropylene fibers on the fracture toughness of cement-stabilized macadam, the three-point bending experiments of polypropylene fiber-reinforced cement-stabilized macadam and common cement-stabilized macadam were carried out. The fracture energy, the crack mouth opening displacement and the crack tip opening displacement of the specimens were also measured. Moreover, an appropriate volume fraction of polypropylene fibers was suggested, namely, 0.6‰ to 0.‰. Test results indicate that （ 1 ） the fracture energy, the ultimate crack mouth opening displacement and the ultimate crack tip opening displacement of cement-stabilized macadam obviously increase when the macadam is reinforced with polypropylene fibers, and gradually increase with the volume fraction of the fibers ; （2） with the prolonging of curing period, the fracture energy gradually increases with the curing period no matter whether polypropylene fibers are added in the macadam or not; and （3） with the increase of cement content, the ultimate load gradually increases while the fracture energy gradually decreases.