短切柔性纤维对密实型沥青混凝土断裂特性的影响

纤维对沥青混凝土的改性效果已得到道路工程界的广泛认可,为探讨不同纤维对沥青混凝土断裂特征的影响,以玻璃纤维和玄武岩纤维作为研究对象,进行半圆抗拉试验,采用数字图像相关技术对半圆试件的全场位移与应变进行实时测量。通过分析极限抗拉强度、极限破坏应变、模量、裂缝缝嘴张开位移、临界断裂能、断裂韧性等指标,探讨了不同纤维对沥青混凝土抗裂性的增强效果。结果表明,两种纤维均能有效改善沥青混凝土的极限强度与破坏延性,纤维改性沥青混凝土具有更高的峰后持荷能力,在沥青混凝土开裂后仍能保持较高的承载能力。玻璃纤维改性沥青混凝土具有更高的临界断裂能量和断裂韧性,基于所选指标建议在工程应用中短切纤维长度不宜超过12 mm。

Effect of chopped flexible fibers on the fracture characteristics of dense asphalt concrete

The improving effect of fibers on asphalt concrete has been widely recognized in pavement engineering. In order to explore the influence of different fibers on the fracture characteristics of asphalt concrete, glass fiber and basalt fiber were selected in this research. The semi-circular bend test was carried out, digital image correlation (DIC) technique was adopted to measure the full-field displacement and strain in real time. The ultimately flexural strength, strain, modulus, crack mouth opening displacement (CMOD), critical fracture energy and fracture toughness were analyzed. Effect of fibers on crack resistance of asphalt concrete was discussed. Results show that both fibers can effectively improve the ultimate strength and ductility of asphalt concrete. Fiber modified asphalt concrete has higher bearing capacity in the post-peak stage, it means that asphalt concrete can bear higher load after it cracks. Glass fiber modified asphalt concrete has higher critical fracture energy and fracture toughness than the others. Based on the selected properties, it is suggested that the length of chopped fiber should not exceed 12 mm in engineering application.