Preparation And Microstructure And Properties Of Polyester Fibers Reinforced Pavement Asphalts

In order to meet the requirement of ever increasing traffic and over loading vehicles , asphalt pavement technologies must be updated accordingly. Pavement asphalts reinforced with polyester fibers have shown well-known good performance and cost effectiveness,and will be widely applied in China's construction of highway and expressway.In this thesis, polyester fibers reinforced pavement asphalt was prepared with roller plasticator. The microstructure and properties, especially for interfacial adhesion, thermal stability and tensile fatigue resistance of the resultant fibers reinforced asphalt mixtures were investigated in detail. The pavement performance of fibers reinforced asphalt concrete was studied as well. The main important findings are as follows:(1) The softening point temperature of polyester fibers reinforced asphalt binders increased while penetration and elongation decreased with the increase of polyester fibers. A stable three-dimensional network in the reinforced asphalt is established when fiber content arrives at 3%. This implied that the modified asphalt experienced the transition from the sol-gel state into the gel state. The primary properties of polyester fibers modified asphalt binders are the following: softening point 135~150oC, penetration (at 25oC) 28~29 and elongation (at 25oC) 14~16 cm.(2) The changes of the softening point and the penetration of polyester fibers reinforced asphalt binders were insignificant in comparison with those of pure asphalt after the samples were subjected to RTFOT experiment. Thus, thermo-oxidative stability of asphalt was improved with polyester fibers. Pure asphalt showed no fatigue resistance since its rupture work approximated zero, whereas the rupture work and fatigue resistance of the polyester fibers reinforced asphalt binder increased rapidly with the increasing fibers. The rupture work and fatigue resistance of the modified asphalt tended to constant after the fibers content exceeded 4%. Fiber C showed the comprehensive and superior improvement to the other three. Consequently the intrinsic viscosity and diameter of fibers dominated the amelioration efficiency.(3) Fiber pull-out experimental results indicated that the interfacial shear strength increased by 10% after the fiber surfaces were pretreated with sizing agent made in our lab.(4) With the fiber dosage 0.25wt%, the dynamic stability (DS) of the polyester fibers modified asphalt concrete increased by 34%, while the residual stability increased from 86.3% for the virgin asphalt to 94.8% for the modified asphalt.The innovation points of this study are two:1. In order to imitate the stress state of asphalt pavement during service, the oscillation experiment was designed and used to evaluate the fatigue resistance of polyester fibers reinforced asphalt.2. The polyester fibers were successfully and uniformly dispersed into asphalt matrix with roller plasticator.