Study On Pore Characteristics Of Cement Stabilized Macadam

Cement stabilized macadam material has always been the main material of high-grade highway pavement base in China due to its strong bearing capacity and convenient materials,but cement stability base is not perfect.Due to the influence of load and service life,the structural function of the water stabilized base will decline,resulting in problems such as pore cracks,which continue to develop and expand to form down-up cracks and reduce road use.Therefore,in order to improve the service performance of cement stabilized macadam materials and strengthen the design concept of long-life pavement,this paper uses uniaxial load to simulate the load,and studies the development mechanism of pore cracks in water stable base.(1)Two groups of N1 and N2 cement stability specimens were designed.After curing,the strength requirements were met.The uniaxial graded loading was set as 0k N,20 k N,40 k N and 60 k N,respectively corresponding to the physical conditions of no load,initial load,middle load and final load.CT technology was used to scan the real damage condition of the cement stability specimens under different load levels,preprocess the CT image of cement stability,and obtain the pore information with the help of image processing technology to carry out the follow-up study on the plane and three-dimensional pore characteristics.(2)The research of plane porosity focuses on three aspects:plane porosity,pore fractal dimension and pore numerical simulation.Plane porosity was an accurate quantitative index of plane pore structure,which had the characteristics of continuity,monotonicity and randomness.Plane porosity reflected the influence of graded load on plane porosity;pore fractal dimension represented the self similarity of pore structure,and fractal dimension was used to describe the self similarity of pore structure.The self similarity of shape dimension described the change of complexity and disorder of pore structure caused by graded load;the numerical simulation of pore was the verification of pore structure performance,and the simulation resulted show that the pore area was the weak point of cement stable material.(3)In the study of three-dimensional pore characteristics,the plane pore was given three-dimensional information,the three-dimensional visualization model of cement stabilized macadam was constructed,the pore visualization model was segmented,the three-dimensional network model of pore was obtained according to the central axis method and the maximum ball method,and the pore characteristic parameters of the three-dimensional model were solved by using the mathematical relationship,and the hierarchical load,pore coordination number and pore volume size were studied.The relationship between coordination number and load represented the connectivity of pore structure,the relationship between pore size and load represented the variation of pore size inside the material,and the relationship between throat and load represents the pore expansion state of the material.This paper describes the development process of pore cracks of cement stabilized macadam materials from the micro and macro point of view,reveals the damage mechanism of water stable materials caused by load,and provides positive guidance for the prevention of road damage.