Research On Key Technology Of Large-sized Cement Stabilized Crushed Stone Mixing Device

Double-layer cement stabilized macadam base with double-layer asphalt pavement layer is a commonly used structural form of highways in China.Although it has the advantages of good overall performance and low cost,the problem of road life decline caused by semi-rigid reflective cracks has not been properly solved.As a new pavement base structure,the water-stable filling large-diameter crushed stone base layer overcomes the shortcomings of the short life of traditional pavement bases,greatly increases the service life of highways,and is gradually widely used.During the construction of the base course,the mixing quality of the large-diameter crushed stone and the cement stabilized crushed stone will seriously affect the strength of the base course,so it is the key to improve the strength of the base course and the life of the highway when ensuring the mixing quality of the material during the construction process.This article takes the Large particle size cement stabilized crushed stone mixing device as the research object,and studies the key technologies involved in the construction process,mainly including the design of mixing cutter and determining the optimal speed of the rotor during mixing,so as to improve the mixing quality of materials.Firstly,through the analysis of the working conditions of the mixing device,the overall plan of the tool design was determined,and the structure,material and heat treatment method of the tool were designed based on the plan.Secondly,the force of the cutter during operation was calculated,and the finite element analysis software Ansys Workbench was used to perform a static analysis for the designed cutter to ensure its strength and stiffness.In order to determine the optimal speed of the rotor,this article uses EDEM simulation software to simulate the mixing process of material,which mainly includes: selecting a suitable particle model through analysis,selecting a hard ball model as a simple model of particles,and selecting a Hertz-Mindlin with JKR model as the contact type of particles.The method of simulation and experiment is used.The combination of simulation and experiment was used to determine the dynamic and static friction coefficient and surface energy of wet particles of cement stabilized crushed stone using the angle of repose as theevaluation index calibration of contact parameters;The grading and mass ratio of large-diameter crushed stone and cement stabilized crushed stone were determined,EDEM software was used to simulate the mixing process of the particles when the rotor speeds is65r/min,90r/min,120r/min,and 150r/min.The distribution of different quality particles,their trajectories and speeds are proposed.The discrete coefficient is used as an evaluation index to analyze the uniformity of the mixture at various speeds.The dispersion coefficient of different size particles in the mixture is calculated.The mixing material has the smallest dispersion coefficient and the best uniformity when rotor speeds is 120r/min;The simulation results were verified by field tests.It was found that the uniformity of the mixture after mixing the materials at a rotation speed of 120r/min was good and met the construction requirements.Finally,120r/min was selected as the optimal mixing speed.