Research On High-Density Paving And Density Perception Technology Of Asphalt Pavement Surface Layer

When the density of the surface layer of asphalt pavement is low,it is easy to cause loosing,cracked,water-damaged and rutting,which directly affect the service life and durability of the pavement.The construction of asphalt pavement mainly relies on the rolling process to improve the pavement density.Due to the thin surface layer,the temperature is dissipated quickly during the rolling process and over-rolling is not recommended,making it difficult to compact the pavement.During the paving construction,perceiving the density of the surface layer during paving and adjusting the paving parameters in a timely manner to achieve a high-density state of the surface material can effectively improve the construction quality of the asphalt pavement surface layer and reduce the difficulty of the rolling process.However,the current paving technology mainly focuses on the pavement flatness.To improve the density of the pavement,the vibratory tamping impact force is mainly used to achieve a high-density effect of the base material.Effective methods and techniques to improve the density of the surface layer material are still lacking.This dissertation aims to solve the problem of low-density of the surface layer of asphalt pavement and carries out research on high-density paving and density perception technology adopting the method of combining dynamic model establishment,simulation analysis,laboratory and field test.The main work completed is as follows:(1)The compaction characteristics of surface layer asphalt mixture are studied.A nonlinear fractional derivative Burgers viscoelastic constitutive model is established which is suitable for describing the mechanical properties of asphalt mixture under high-density paving.The variation of compaction characteristics of asphalt mixtures under the influence of temperature,gradation and other factors are studied.The temperature and material gradation suitable for high-density paving of surface layer are obtained,which provides a theoretical basis for the compaction test research of high-density paving.(2)The construction parameters matching for high-density paving of surface layer is studied.The optimum matching method of construction parameters for surface layer paving is obtained through the orthogonal test.The sufficient and necessary conditions for high-density paving of surface layer asphalt mixture are analyzed.Base on the working principle of paver and the viscoelastic constitutive relation of asphalt mixture,the paving compaction process model is constructed.The variation law of pavement density during the screed moving is studied.The matching principle of the screed vibration frequency and the paving speed during the paving construction is proposed,which provides a theoretical basis for the selection of construction parameter in high-density paving technology.(3)The vibration characteristics of screed during high-density paving of surface layer are studied.By considering material characteristics and energy absorption efficiency during paving compaction,a multi-degree of freedom nonlinear system of the screed-asphalt mixture interaction is established.The influence of the nonlinear dynamic characteristics of the interaction between the asphalt mixture and the screed on the pavement density are studied.The model is verified through field tests and the optimal parameter range of the high-density paving compaction is obtained.(4)The high-density perception technology of surface layer based on the paving compaction characteristics is studied.The raw signal of the screed dynamic response at the paving site is analyzed and processed using empirical mode decomposition.The effective spectral components reflecting the vibration state of the screed are obtained.According to the frequency spectrum characteristics of the response signals,a high-density perception index CEV(Compaction Energy Value)based on the vibration compaction energy distribution is proposed.The index value could reflect the on-site paving density,and the technology could realize the evaluation of the paving compaction state of the surface layer.(5)The high-density paving perception system CMS-01 for asphalt pavement surface layer is developed and applied in practice.A high-density paving perception field test is carried out using SUP-13 asphalt pavement surface layer as an engineering example,verifying the effectiveness of the system.