Performance Evaluation And Improvement Measurements Of Iron Tailings Asphalt Mixture

The low utilization rate of iron tailings has become a difficult industrial problem.If it is applied to the construction of pavement engineering,it can not only reduce the development of natural rock,but also solve the environmental problems caused by a large number of iron tailings.It has important economic,social and environmental benefits.By analyzing the basic properties of the iron tailings and comparing the difference between the iron ore tailings and the conventional aggregates,iron tailings have the conditions for replacing road aggregates,and the performance evaluation of the iron tailings asphalt mixture is evaluated.The improvement measures are put forward according to the performance shortage of the iron tailings asphalt mixture,and the iron ore tailings asphalt mixture with good road performance is obtained.Iron tailings,as road aggregate,are the basic and precondition of road performance of asphalt mixture.In physical properties,the density and water absorption,particle size composition,pin content,mud content,pore volume and pore size distribution,surface morphology and the density,gradation composition of iron tailings sand.In chemical properties,X ray fluorescence analysis(XRF)and X ray diffraction analysis(XRD)were used to determine the element,chemical composition and phase composition of the iron ore tailings,.The mechanical properties of the iron ore tailings were evaluated by the crushing value and the Losangeles wear value.The weatherability of the iron ore tailings were evaluated by the sturdiness index,the high temperature stability and low temperature stability.The research shows that iron ore tailings have physical and chemical foundation instead of road aggregate.The difference between iron tailings and conventional aggregate determines that there is a certain deficiency in the road performance of iron tailings asphalt mixture.According to the characteristics of iron tailings,the high temperature stability,water stability and low temperature cracking resistance of iron tailings asphalt mixture are mainly studied.Taking AC-20 as an example,the composition design of iron tailings asphalt mixture is carried out by using the Marshall volume design method.The basic road performance of the iron tailings bitumen mixture under the optimum asphalt content is evaluated.It is considered that the iron tailings sand should not be used as a fine aggregate into the asphalt mixture,The performance of the iron ore tailings A asphalt mixture is not as good as that of the iron ore tailings B,then the application of iron ore tailings B is further studied.According to the problems existing in the iron ore tailings B asphalt mixture,the method of replacing the fine aggregate and asphalt is adopted to improve the performance of the asphalt mixture,but the road performance of the iron ore tailings B asphalt mixture has a gap with the basalt asphalt mixture.According to the road performance gap between the iron ore tailings B asphalt mixture and the basalt asphalt mixture,the way of adding the hydrated lime and silane coupling agent to improve the road performance of the iron ore tailings B asphalt mixture is further improved.According to the effect of the lime on the pavement performance of iron ore tailings B asphalt mixture and the influence of silane coupling agent on the properties of rubber /SBS composite modified asphalt,the optimum amount of them was determined and the improvement mechanism was analyzed.The improvement effect of two improvement methods was compared,the two improvement measures have positive effects on the high temperature stability,water stability and low temperature cracking resistance of asphalt mixture.Relatively,the high temperature stability of the iron ore tailings B asphalt mixture is improved obviously with the addition of slaked lime,the iron ore tailings B asphalt mixture added with silane coupling agent has better crack resistance at low temperature.