| The research in this paper relies on the subject of “mixture ratio Optimization and Construction Control of Asphalt pavement in Ji-cao Expressway” and “Research on pavement performance data Model of Asphalt mixture based on Cloud platform”.The related research was carried out based on Jichao Expressway project.The research is based on the geological environment along the Jichao Expressway.The main research object is basalt,andesite and limestone lithotripsy,which produced along the expressway.The properties of the lithotripsy,surface characteristics,asphalt adhesion and the performance of the asphalt mixture made up of the gravels were studied.The idea is to take materials locally,make the best use of materials,and carry out related research work.1.Research and exploration of geological structural characteristics,geographical location,topography,geomorphology and geological conditions along the project.The macadam has good physical and chemical properties and can be used as aggregate of asphalt mixture.The physical and chemical properties of macadam are closely related to the composition,and the distribution of quarries is regional.The physical and chemical properties of macadam materials are closely related to the composition,and there is a certain regularity in geographical distribution,the geographical distribution of quarries is regional.Based on the physical and chemical properties of aggregates,the applicability of aggregates and grades is studied.Basalt aggregates are suitable for discontinuous grades,and andesite and limestone aggregates are more suitable for continuous grades.2.The surface texture and roughness of aggregate are the key factors that affect the performance of asphalt.Based on the microscopic digital images,the conventional geometrical parameters and fractal dimension of the surface of the gravel are observed.Using the concept of dendritic cells in the field of medical and image analysis,this paper introduces the characteristics of dendritic texture,and analyzes the texture characteristics of gravel from the point of texture continuity and mutation texture.The results show that the number of dendritic textures can be used to evaluate the texture characteristics of gravel surface.The number of basalt dendritic veins is significantly lower,only about 40% of the limestone average,and the number of andesite dendritic textures is slightly below that of limestone,averaging 85% of the limestone level.Limestone gravel surface is the most rough,rich texture,the corresponding area,circumference and distribution density is larger.The surface texture characteristics of basalt and the andesite are similar,and the indexes of the andesite are slightly higher than basalt.The textures of basalt,andesite and limestone can be distinguished by three parameters of texture distribution density,counting box dimension and dendritic texture.3.The specific surface area and average pore size of macadam surface were determined by nitrogen desorption experiment,and the surface roughness of macadam was evaluated by mutual confirmation with texture characteristic data.Limestone is a sedimentary rock,the surface is coarser than basalt and the rock,and the texture of the crushed stone in different quarries is very different.The average pore size of basalt is similar to that of the andesite,and the surface texture of gravel produced by different quarries is close.4.Based on gravimetric method,the spalling rate of asphalt and asphalt mortar on macadam surface was determined.The effect of asphalt mortar on the surface of macadam is better than that of pure asphalt,low peeling rate and strong adhesion.From the microscopic image observation of the adhesion of asphalt mortar on aggregate surface,it shows that the surface roughness of crushed stone is improved indirectly by mineral powder particles adhered to the macadam surface,and the adhesion thickness of asphalt on the macadam surface is increased.The adhesion effect of asphalt on macadam surface is improved obviously.Limestone aggregate has good adhesion to asphalt,and the asphalt peeling rate on the surface and the asphalt slurry peeling rate are close to each other.5.Based on the surface energy theory,the paper analyses the spreading of asphalt on the gravel surface.A method of measuring spreading radius is proposed to evaluate the spreading level of asphalt on gravel surface.At 150 ? mixing temperature,the asphalt can spread freely on the gravel surface.After dropping on the surface of the gravel,the asphalt droplets continue to be heated for 3 minutes and spread out to achieve the free energy balance of solid,liquid and gas surfaces.Based on the surface energy theory and energy conservation theory,the spreading radius can be used to evaluate the spreading degree of asphalt on the gravel surface.The more smooth the surface of gravel,the larger the spreading radius,the rougher the surface,the smaller the spreading radius.The surface of limestone is the most rough,the surface pore is the most complex and the spreading radius is the smallest.The surface roughness of basalt macadam is similar to that of the mountain rock.6.Based on the orthogonal experiment method,the coarse aggregate,gradation scheme and oil stone were compared to three control factors,and three types of gravel from 9 quarries were designed to design 27 sets of asphalt mixture specimen sample scheme.The physical parameters and road performance parameters of asphalt mixtures are determined.Based on factor analysis method,the performance of asphalt mixture pavement is simplified into three main performance characteristics: adhesion,stability and durability,and the three main performance characteristics were taken as x-axis y-axis and z-axis.Three dimensional coordinate space is established.The scatter distribution of 27 sets of asphalt mixtures in the three-dimensional coordinate space is plotted by using the road performance factor score of 27 groups as coordinates.27 scattered points show obvious regional distribution characteristics in three-dimensional space.The scattered distribution area of SMA and ATB asphalt mixture is relatively concentrated and the road performance is stable.7.Using green spline interpolation and curved surface fitting to fit the distribution area of performance factor of asphalt mixture.SMA,AC and ATB scatter-fitting surfaces are independent to each other.The relationship between the performance of asphalt mixture and the physical and chemical indexes of aggregates can be established by factor analysis method,and the performance distribution characteristics of asphalt mixtures with different lithology,different gradation types and different oil asphalt are clearly distinguished in the model.It is known from scatter distribution and fitting surface that the adhesion of SMA asphalt mixture is high,the durability performance is different,and the stability level is lower than the other two kinds of asphalt mixtures.The stability and durability of AC asphalt mixture are unstable,at two extremes,but the adhesion is good,it is in the middle level of SMA and ATB.The adhesion level of ATB is low,the stability and durability level are in the middle,the overall performance distribution is more concentrated,and the mixture performance is stable. |
PDF Full Text Request