Research On Road Performance Of Coal Gangue Powder Modified Rubber Asphalt Mixture

Waste tires and coal gangue are two major wastes produced in China’s economic development.Rubber asphalt can be made by adding rubber powder made of waste tires to matrix asphalt,and the performance of rubber asphalt pavement is better than that of matrix asphalt pavement.However,there are few reports on the application of coal gangue grinding into powder as filler in rubber asphalt mixture.In view of this,the properties of modified asphalt mortar were studied with limestone powder and coal gangue powder as fillers.The modified rubber asphalt mixture was prepared,and the road performance of rubber asphalt mixture was studied.The main contents are as follows:（1）The microscopic technical characteristics of limestone powder and coal gangue powder were tested.The results show that the surface structure of coal gangue powder is complex,while the surface structure of limestone powder is smooth.The particles of coal gangue powder are mainly distributed in the small particle size range.In addition,coal gangue powder contains more Si O₂and Al₂O₃active oxides than limestone powder.（2）Limestone powder modified base asphalt mortar（LPMBAM）,limestone powder modified rubber asphalt mortar（LPMRAM）and coal gangue powder modified rubber asphalt mortar（CGPMRAM）were prepared according to different powder-binder ratios.The softening point test and bending beam rheology（BBR）test of modified asphalt mortar were carried out.The results show that the performance indexes of rubber asphalt mortar are improved compared with matrix asphalt mortar.The high temperature performance and temperature sensitivity of CGPMRAM are improved,while the low temperature performance is slightly decreased.Based on the shear strength and stiffness modulus,the double linear model was used to determine the optimal powder-binder ratio range of LPMRAM from 0.44to 0.46,and the optimal powder-binder ratio range of CGPMRAM from 0.42 to 0.43.The Brookfield rotational viscosity test was carried out on the modified rubber asphalt mortar under the optimum powder-binder ratio.It was found that the viscosity of CGPMRAM was larger and the viscosity-temperature index was lower.（3）The density and pass rate of each aggregate were tested.The gradation design of ARHM-13（W）was carried out with limestone powder and coal gangue powder as fillers respectively,and Marshall specimens with two kinds of fillers with different oil-stone ratios were made.Through the calculation of Marshall test index,the optimum asphalt-aggregate ratio of limestone powder filled rubber asphalt mixture is 4.9%,and the optimum asphalt-aggregate ratio of coal gangue powder filled rubber asphalt mixture is 5.0%.Comparing the Marshall test indexes of the two fillers,the results show that the physical and mechanical properties of the Marshall specimens with coal gangue powder as filler are improved.（4）Limestone powder rubber asphalt mixture（LPFRAM）and coal gangue powder rubber asphalt mixture（CGPFRAM）with the best oil-stone ratio were prepared respectively.Rutting test,trabecular bending test and freeze-thaw splitting test were carried out on the two rubber asphalt mixtures.The results show that the high temperature performance and water loss resistance of CGPFRAM are improved compared with LPFRAM,but the low temperature performance is reduced.（5）According to the field pavement structure and related literature research,ABAQUS is used to establish the pavement structure model.The matrix asphalt pavement and rubber asphalt pavement were selected for comparative analysis.The standard double wheel load is applied according to the specification,and the stress response under different upper layer thickness and load conditions is compared.The results show that under the same conditions,the surface deflection and bottom stress of rubber asphalt pavement are smaller and the shear stress is larger than that of matrix asphalt pavement.With the increase of the thickness of the upper layer,the surface deflection and the bottom stress of the surface layer of the matrix asphalt pavement and the rubber asphalt pavement decrease,and the shear stress increases.With the increase of load,the surface deflection,pavement shear stress and surface layer bottom stress change greatly.