Study On The Abrasion Characteristic Of Surface Texture And Its Effect On Noise For Asphalt Pavements

The pavement surface texture will be abraded due to traffic loads during the service life of asphalt pavements,and this will affect the variation of pavement noise.At present,testing the pavement noise and surface texture on the same road section at certain intervals is commonly used to investigate the variation of the pavement surface texture and noise,as well as their correlation.Whereas,the tests are difficult to conduct and the overall material information of the tested road section is difficult to obtain.In addition,previous accelerated abrasion machines are deficient in the slip rate,abrasion direction and specimen size.It's difficult to acquire pavement surface texture and noise under the same abrasion condition.According to these deficiencies and the research demand of surface texture abrasion characteristics and its impact on asphalt pavement noise,this dissertation attempts to conduct in-depth research in terms of laboratory abrasion machines,characterization of surface texture and abrasion characteristics and their influencing factors,optimization of the laboratory pavement noise test method,and correlation analysis of texture attenuation and pavment noise for asphalt pavements.This will lay the foundation for laboratory research on the variation of asphalt pavement noise.In this research,a more reasonable laboratory abrasion machine was developed.The evaluation index system for deterioration characteristics of pavement surface texture was established,and using thses indexes,the effect of key material parameters on deterioration characteristics of pavement surface texture was analyzed.The Rolling-Tire-down Tester?RTT?,as well as its test method were optimized.On this basis,the effect of surface texture deterioration on noise was revealed,and the pavement noise variation by the RTT method was further analyzed from the perspective of pavement surface texture.Firstly,in this dissertation,characteristics and problems of previous accelerated abrasion machines at home and abroad were summarized,and a new accelerated abrasion machine named Multivariable Accelerated Abrasion Machine?MAAM?was developed.It could achieve one-way abrasion and adjustable slip rates.Its key parameters,such as design parameters of abrasion wheel,travelling speed,tire contact pressure,slip ratio,etc.were determined.The effect of the emery as polishing agents,measuring positions and slip rates on the abrasion effect was analyzed.Based on significance analysis of Mean Profile Depth?MPD?after different passes of abrasion,the number of abrasion passes when the abrasion process was stopped was determined.Through continuous improvement of MAAM and experiment analysis on the rationality of the devices,MAAM standard test conditions were proposed.Travelling speed was 12.5 passes of one-way abrasion per minute;tire contact pressure of the abrasion wheel was 0.7MPa;slip rate was 15%;the abrasion was stopped after 24000 passes of abrasion;the Position 5 in the center abrasion area was recommended as reference position and the emery was spread 100g per 1000 passes of abrasion to accelerate the abrasion process.Secondly,the key test parameters of Laser Texture Scanner?LTS?,pavement profile elevation data acquisition,as well as the processing method of the dropouts,inclination and bias error by MATLAB programming were analyzed and studied.The pavement surface texture evaluation indexes,including macro-texture,micro-texture,positive/negative texture,and texture spectrum,were calculated.According to the evolution rule of pavement surface texture indexes in the abrasion process and contrasts between different texture indexes,MPD,micro-texture level L_TX,0.06?_0.5,characteristic wavelength texture level L_TX,ch and characteristic wavelength W_maxax were selected to study abrasion characteristics of pavement surface texture.Thirdly,taking Asphalt Concrete?AC?and Stone Mastic Asphalt?SMA?pavements as research object,gradation composition,nominal maximum aggregate size?NMAS?,aggregate type and asphalt-aggregate ratio?AAR?were selected as key material parameters of asphalt mixtures.Their influence on pavement initial surface texture was analyzed.On this basis,their influence on surface texture deterioration of asphalt pavements was further analyzed from the perspectives of macro-texture,micro-texture and texture spectrum.Based on gray relational entropy analysis results,Multiple Linear Regressions?MLR?between Texture Deterioration Degree?TDD?and different combinations of key material parameters were conducted.The TDD of MPD was proposed as the evaluation index for abrasion resistance of pavement surface texture and its linear regression model was established with three variables including NMAS,aggregate Los Angeles abrasion?LAA?value and key sieve passing rate.Fourthly,based on the existing RTT and the problems of the test method,the third generations of RTT system and test methods were further studied.When analyzing the influence of interception methods of time-sound pressure data on noise analysis,high-speed camera and gravity sensor were used to accurately identify the interaction between tire and pavement specimen.The key control parameters for the laboratory RTT test method were determind.The interaction time between the tire and the pavement was 28ms;the starting point of the interception was 1ms before the turning point of time-sound pressure data in the whole process;acquisition rate was proposed as 36571Hz;the intercepted data amount was1024;the microphones should be placed on both sides.Comparative analysis of laboratory and on-site noise test results showed that Sound Pressure Level?SPL?tested by the improved RTT method approached that tested by On-Board Sound Intensity?OBSI?at a speed of50km/h,and the 1/3 octave band spectrum was generally located between the OBSI test results at a speed of 40 km/h and 50 km/h.Finally,for typical pavements AC and SMA,the variation of total SPL with MPD,L_TX,0.06?_0.5,g and L_TX,ch was analyzed.It was found that single surface texture index and total SPL couldn't fully reveal the correlation between surface texture and noise.The piecewise thresholds of surface texture and noise spectrum were proposed.On this basis,the variation of piecewise texture spectrum and piecewise noise spectrum,as well as their correlation,were analyzed.Furthermore,the main reason for the pavement noise variation were revealed,namely the decrease of short wavelength texture level L_TX,0.5?₈ led to the significant increase of high frequency noise SPL₁₆₀₀?₅₀₀₀.Accroding to OBSI test results,SPL₁₆₀₀?₅₀₀₀ was the main component for pavement noise increase with increasing test speeds.