Mechanical Properties And Calculation Methods Of Fiber Reinforced Asphalt Concrete

With the rapid development of the highway transportation, the early damage phenomenon in traditional pavement material and structure is very common such as rutting, pits, loose and so on, so traditional pavement material and structure are very difficult to meet the needs of modern traffic. Fiber reinforced asphalt concrete has got more and more attention because of its excellent road performance. In this paper, the road performance and mechanical properties of fiber reinforced asphalt concrete were researched in-depth through experiment and theoretical analysis; the main contents are as follow:(1) Through the Marshall test of 12 graded series of fiber reinforced asphalt concrete, the effects of fiber type, fiber volume ratio and fiber aspect ratio on the gradation of fiber reinforced asphalt concrete were studied, optimum asphalt content in fiber reinforced asphalt concrete was obtained; Using fiber content characteristic parameter to reflect the comprehensive effect of fiber volume ratio and fiber aspect ratio on optimum asphalt content in asphalt mixture, the calculation method of optimum asphalt content in fiber reinforced asphalt concrete was put forward based on the optimum asphalt content of matrix asphalt concrete. The Marshall test, rutting test and immersion Marshall test of fiber reinforced asphalt concrete were conducted under optimum asphalt content, the relationship between the road performance and composition of fiber reinforced asphalt concrete was analysised.(2) By bending test of 240 fiber reinforced asphalt concrete beam specimens, the influences of temperature, fiber type, fiber volume ratio and fiber aspect ratio on the fiexural performance of fiber reinforced asphalt concrete were studied, the calculation models were established for the indexes of fiber reinforced asphalt concrete flexural properties considering the effect of fiber content characteristic parameter. The results show that, at-30～15℃, the flexural tensile strength of fiber reinforced asphalt concrete increased first and then decreased with increasing temperature, maximum value appears at 0℃, at this time the fiber reinforced asphalt concrete shows obvious stress softening characteristics; Within suitable fiber volume ratio and fiber aspect ratio, fiber can improve asphalt concrete’s low temperature crack resistance and high temperature deformation resistance.(3) Through the bending creep test of 24 polyester fiber reinforced asphalt concrete beam specimins at 15℃, the effects of fiber volume ratio and fiber aspect ratio on the creep test parameters were studied. Based on Burgers model and modified Burgers model, the viscoelastic mechanicaknodel and constitutive equation of fiber reinforced asphalt concrete were established considering the comprehensive influence of fiber volume ratio and fiber aspect ratio, and the viscoelastic performance was analyzed. The results show that, when the fiber volume ratio is 0.35%, the fiber aspect ratio is 324 and the fiber content characteristic parameter is 1.13, the polyester fiber reinforced asphalt concrete has better resistance to elastic deformation, viscous flow deformation, rutting deformation and the viscoelastic deformation self-healing ability after unloading; Based on analysing the creep deformation characteristics of fiber reinforced asphalt concrete, the new model of Five Unit Eight Parameter for fiber reinforced asphalt concrete was proposed to characterize ifs viscoelastic properties, the viscoelastic performance of fiber reinforced asphalt concrete was analized using this model. The results show that, the new model can reflect the rheological time feature and better characterize the creep deformation property of fiber reinforced asphalt concrete.(4) Based on the splitting test of 240 fiber reinforced asphalt concrete specimens, the effects of fiber type, fiber volume ratio, fiber aspect ratio and temperature on the splitting performance of asphalt concrete were studied, the relationship between temperature and splitting test parameters of polyester fiber and basalt fiber reinforced asphalt concrete and splitting test parameters calculation model of polyester fiber reinforced asphalt concrete were established considering the influence of the fiber content characteristic parameter.(5) Through splitting fatigue test of 128 polyester fiber reinforced asphalt concrete specimens, the influences of the fatigue loading stress level, fiber volume ratio and fiber aspect ratio on the splitting fatigue performance of asphalt concrete were researched. Combining the theory of damage mechanics, the fiber reinforced asphalt concrete’s fatigue failure criterion was established unified phenomenological method and damage mechanics method; the fatigue life calculation models were established considering the effect of loading frequency and comprehensive effect of fiber volume ratio and fiber aspect ratio.(6) Through the thermal stress restrained specimen test of 24 polyester fiber reinforced asphalt concrete specimens, the influences of the fiber volume ratio and fiber aspect ratio on the low temperature anti cracking performance of asphalt concrete were studied, TSRST test parameters calculation models and the fiber reinforced asphalt concrete pavement temperature stress calculation model were established considering the comprehensive effect of fiber volume ratio and fiber aspect ratio.The research of fiber reinforced asphalt concrete’s road performance and mechanical properties in this paper show that, when the polyester fiber volume ratio is 0.35%, the fiber aspect ratio is 324, polyester fiber reinforced asphalt concrete has better road performance, bending performance, splitting performance, fatigue durability performance and low temperature crack resistance performance; When the basalt mineral fiber volume ratio is 0.52%, basalt mineral fiber reinforced asphalt concrete has similar performance.