| At present,a lot of work has been done on the properties of mineral powder in asphalt mixture,but there is little research on the influence of mineral powder properties on the long-term road performance of asphalt mixture.Therefore,according to the climatic conditions in Heilongjiang Province,this paper will study the influence of the physical and chemical properties of mineral powder on the freeze-thaw resistance of asphalt mixture.Based on the above reasons,this paper will first analyze the influence of mineral powder properties on the performance change of asphalt mortar under freeze-thaw cycle,then use molecular dynamics method to study the adsorption performance between mineral composition in mineral powder and asphalt under different control conditions,and finally use random forest method to study the influence of mineral powder properties on the performance decay law of asphalt mixture after freeze-thaw cycle,so as to guide the selection and application of mineral powder.Firstly,the chemical composition and character of surface of different asphalt mortar after freeze-thaw cycles were studied by Fourier transform infrared spectroscopy and atomic force microscope,and the changing rule of rheological properties of asphalt mortar was obtained,which effectively combined the macro-rheological properties and micro-state of asphalt mortar.Using the random forest method in data mining,the importance degree of the influence of different properties of mineral powder on the performance change of asphalt mortar is obtained.Secondly,based on the molecular dynamics method,the interface contact model between asphalt and main minerals in mineral powder is established.According to the two-phase contact model after dynamic simulation,the difference between the whole potential energy and the sum of potential energy of each part,i.e.interface energy,is used to measure the adhesion between minerals and asphalt.The interface energy of the mixed mineral and asphalt contact interface is calculated,and the influence of different impurities on the adhesion between asphalt and mineral powder is obtained.At the same time,the change of interface energy between asphalt and minerals in the presence of water molecules is simulated,and the interface energy of different mixed minerals is obtained.Finally,the performance change of asphalt mixture under freeze-thaw cycle is studied.Taking void ratio as volume index and Marshall stability as mechanical index,the performance damage law of the mixture formed by different mineral powders under freeze-thaw cycle was obtained.Using logistic model,the damage law of asphalt concrete is predicted.Freeze-thaw cycles when Marshall stability damage degree and the void ratio damage degree reaches 25% are used as the durability evaluation indexes of asphalt mixture,the influence degree of different properties of mineral powder on freeze-thaw resistance of asphalt mixture is obtained by random forest method,and the technical index requirements of mineral powder are improved according to the importance degree. |
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