添加PVA纤维的水泥稳定碎石混合料抗裂与耐久性能研究

Study on Crack Resistance and Durability of Cement Stabilized Macadam Mixture with PVA Fiber

基于7 d无侧限抗压强度、劈裂强度、弯拉强度研究了聚乙烯醇(PVA)纤维掺量及长度对水泥稳定碎石力学性能的影响,优化出适宜的纤维掺量和长度;进而通过干缩试验、温缩试验、疲劳试验、冻融循环试验,研究了PVA纤维水泥稳定级配碎石混合料的变形特性和疲劳性能,基于SEM试验揭示了PVA纤维的增强机理。结果表明,掺加PVA纤维显著改善了水泥稳定碎石混合料的抗压强度和弯拉强度,PVA纤维提高了水泥稳定级配碎石的抗疲劳耐久性和抗冻融性能,并能减少干缩变形和温缩变形。在PVA纤维掺量1.1 kg/m 3、纤维长度20 mm时,水泥稳定级配碎石的各项力学性能、变形特性和疲劳性能达到峰值。锚固在水泥稳定级配碎石中的PVA纤维具有协同受力、传递荷载、协调变形的作用,从而有效延缓了破坏裂纹的产生和发展。实体工程跟踪检测结果表明,掺加PVA纤维可以提高水泥稳定碎石基层的抗压强度,阻止半刚性基层产生反射裂缝,并延缓半刚性基层产生疲劳开裂,PVA纤维水泥稳定碎石基层具有推广应用价值。

Based on the 7 d unconfined compressive strength,splitting strength and bending strength,the effects of the blending amount and length of polyvinyl alcohol(PVA)fiber on the mechanical properties of cement stabilized macadam were studied,and the suitable fiber content and length were optimized.the deformation characteristics and fatigue properties of PVA fiber cement stabilized graded macadam mixture were studied by dry shrinkage test,temperature shrinkage test,fatigue test and freeze-thaw cycle test.The strengthening mechanism of PVA fiber was revealed based on SEM test.The results show that the addition of PVA fiber significantly improves the compressive strength and bending strength of cement stabilized macadam mixture.PVA fiber improves the fatigue durability and freeze-thaw resistance of cement stabilized graded macadam,and can reduce dryness.Shrinkage deformation and temperature deformation.When the PVA fiber content is 1.1 kg/m 3 and the fiber length is 20 mm,the mechanical properties,deformation characteristics and fatigue properties of the cement stabilized graded macadam peak.The PVA fiber anchored in the cement stabilized graded gravel has the functions of synergistic force,transmission load and coordinated deformation,thus effectively delaying the generation and development of the fracture.The results of physical engineering tracking test show that the addition of PVA fiber can improve the compressive strength of cement stabilized macadam base layer,prevent the formation of reflective cracks in semi-rigid base layer,and delay the fatigue cracking of semi-rigid base layer.PVA fiber cement stabilized macadam base layer has popularized applicationvalue.