Study On Compaction Characteristics Of Cement Emulsified Asphalt Mixture

CEAM(Cement Emulsified Asphalt Mixture)is suitable for pavement construction under special climatic conditions in the high and cold regions of central and western China due to its high strength,outstanding water stability and the ability to achieve normal temperature paving compaction.However,the understanding of the compaction characteristics of the material is not deep enough,which has affected its compaction process design and practical application.Therefore,it is urgent to study and obtain the compaction characteristics of the material,so as to propose a compaction method and construction process suitable for it.The main contents of this paper are as follows:(1)Firstly,the CEAM rotary compaction characteristics test was carried out,and the compaction parameters such as ambient temperature,standing time,spinning angle and spinning number were analyzed for compaction indexes such as compaction strength,compactness and compaction index.The results show that the higher ambient temperature and spinning angle are beneficial to improve the compressive strength and compactness of the test piece,while the compaction rate K and the CEI(Construction Energy Index)are both reduced.In addition,through the material forming index such as compressive strength and compactness,the selection range of the material’s standing time at different ambient temperatures was determined.(2)Secondly,using discrete element software PFC(Particle Flow Code),discrete element modeling is carried out from the mesoscopic layer facing CEAM aggregate.The existing random polyhedron virtual aggregate generation method is analyzed and compared,and the random polyhedral filling method is preferred.The shortcomings of the virtual aggregate’s shape characteristics can not be related to the actual aggregate,and the needle,flatness,sphericity,The polyhedral contour parameters such as angularity restrict the screening of the generated polyhedron,making the virtual polyhedral aggregate closer to the actual aggregate.(3)After analyzing the characteristics of CEAM mesoscopic contact,the contact model between the various phase materials in CEAM is determined,and the relationship between the macroscopic test parameters of each contact type in CEAM and the mesoscopic model parameters in the discrete element is established,and the indoor CA is designed.The mortar constant load creep test obtained the mesoscopic connection parameters corresponding to CEAM.Based on the generation of stochastic polyhedron discrete element aggregates satisfying the actual aggregate shape parameters and the contact parameters of each phase of the material,the three-dimensional discrete element dead load creep virtual experiment model of CA mortar and CEAM was established respectively,and passed the indoor test.Comparative analysis verified the rationality of the model.(4)Finally,by establishing the CEAM rotary compaction discrete element model,the shear stress,shear work,compaction work and the porosity of different positions in the CEAM virtual specimen under different spinning angles were studied.The results show that the shear stress shows a three-stage change during the rotary compaction process.That is,as the spin angle increases,the maximum shear stress increases correspondingly,and the constant shear stress decreases.In addition,the spinner output energy is much larger than the vertical compaction energy and increases substantially linearly.The porosity at the center of rotation is the lowest,and the porosity inside the test piece is positively correlated with the distance from the center of rotation.