Optimization Of Corn Straw Fiber Modification Process Parameters And Performance Study Of AC-13 Fiber Asphalt Mixture

With the increase of traffic volume and traffic load,the new corn straw fiber used in asphalt pavement technology has been studied.However,the road corn straw fiber prepared at present has a slightly weaker improvement effect on the pavement performance of asphalt mixture than lignin fiber,and there are few studies on the straw fiber asphalt mixture.Therefore,this paper puts forward the modification process of road corn straw fiber,and optimizes the process parameters by studying the performance of fiber asphalt.Based on this,the road use characteristics and viscoelastic characteristics of AC-13 modified corn straw fiber asphalt mixture are studied,the optimal fiber content is recommended by comprehensive analysis,and the long-term high temperature performance of its pavement is verified.Firstly,the corn straw fiber obtained from mechanical crushing was modified by Na OH solution.The microscopic structure of the corn straw fiber obtained under different lye concentration and treatment time was observed and analyzed by scanning electron microscopy.It was found that the modified treatment could change the microscopic morphology of the fiber and increase the surface roughness.If the concentration of lye is too small or the treatment time is too short,the surface morphology of corn straw fiber is not obvious.Too much lye concentration or too long treatment time will cause fiber fracture or cavity structure collapse,resulting in damage to the overall structure.When the concentration of lye was 3% and 5%,and the treatment time was 30 min and 40 min,the corn straw fiber showed better roughness and curl.The influence of modification conditions and fiber content on asphalt conventional properties and rheological properties at high and low temperatures was investigated by using cone penetration,softening point,elongation,dynamic shear rheology and bending beam rheology,and the modification process parameters of corn straw fiber were optimized by single factor test.It is concluded that the modified treatment can improve the shear resistance,permanent deformation resistance and stress relaxation ability of fiber asphalt.After comprehensive analysis,the optimum alkaline process parameters of corn straw fiber are 3%alkali concentration and 30min treatment time.Based on the optimum modification technology,AC-13 asphalt mixture mixed with modified corn straw fiber and lignin fiber was designed,and the trend of the optimum oil-stone ratio and stability index with the increase of fiber content was analyzed.The high temperature stability,low temperature cracking resistance,water stability and fatigue properties of the modified maize straw fiber asphalt mixture were studied by rut test,low temperature bending test,immersion Marshall test,freeze-thaw splitting test and fatigue test,and the road performance was analyzed comprehensively.The results show that the asphalt mixture has better road performance when the content of modified corn straw fiber and lignin fiber is 0.2% and 0.3%.The improvement effect of modified corn straw fiber is better than that of lignin fiber under the optimal dosage,and can replace lignin fiber approximately.The viscoelastic parameters were obtained by fitting the fatigue test results with Burgers model,and the dynamic load was applied to analyze the creep strain response to explore the influence of modified corn stalk fiber on the viscoelastic characteristics and creep behavior of AC-13.It is concluded that the instantaneous elastic deformation of asphalt mixture is weakened,the permanent deformation of pure viscosity is reduced,and the accumulation of unrecoverable deformation is reduced.When the content of modified corn straw fiber and lignin fiber is 0.2% and 0.3%,the elastic deformation resistance of asphalt mixture is the weakest,the permanent deformation resistance is the best,and the deformation recovery is the largest.Under dynamic loading,the creep strain of asphalt mixture is minimum when the content of modified corn straw fiber and lignin fiber is 0.2% and 0.3%.The creep strain of modified maize straw fiber asphalt mixture is less than that of lignin fiber under the optimum dosage.Finally,a small pavement performance intelligent monitoring equipment independently developed by the research group was used to design a test method to verify the long-term high-temperature performance of the modified corn straw fiber asphalt pavement.Rut depth was taken as the evaluation index and the rutting development law of fiber asphalt mixture was explored.It is concluded that the permanent deformation resistance of modified corn straw fiber asphalt pavement under long-term high temperature is about 16.3% higher than that of lignin fiber under optimal dosage.