Research On Asphalt Pavement Structure Design Of Wu Shen Expressway In Guang Dong Province

Combining the A1 section design project of Wu Shen expressway from Renhua to Xinfeng( following as “design project”), the author carried on the research analysis for the design parameters of pavement structure. The design parameters of pavement structure consist of structural parameters and performance parameters. Structure parameters contain traffic volume and traffic load, the temperature field parameters of pavement structure, the compressive modulus of resilience and splitting strength of each layer material. Performance parameters cover the raw material performance, the water stability, the anti-rutting performance of high temperature, the anti-crack performance of low temperature, permeability and anti-sliding performance(surface layer),Based on the investigation and analysis of the built expressway in Renhua and surrounding, the exact temperature field of pavement structure was obtained. Based on analyzing vehicle transportation, it was determined that the traffic volume level and traffic load of the design project and the traffic classification.Through field investigation,the raw material quality and the supply of materials were acquired..At the same time,through the experimental study on the technical parameters of raw materials, it found that the adoption of the SBS modified asphalt viscosity was in log-log trend of decline with the temperature increasing.In order to fit the characteristics of the region, that high temperature, rainy and the heavy traffic, the asphalt mixture must meet the requirements, like, even and dense water,anti-rutting, anti-crack and skid resistance. At first, the SAC gradation and modified grading GAC gradation were chosen.And then, the kinds of experiment were carried on that the high temperature stability, water damage resistance, low temperature crack resistance, anti-sliding performance( surface layer) and water penetration. It was found that the asphalt mixture with GAC gradation was better at water damage resistance,economic and widely used in Guang dong province. So the asphalt mixture with GAC gradation was selected for the next study.First of all, the rutting test of asphalt mixture GAC-20 C was carried out respectively with the domestic wheel grinding test and APA asphalt pavement analyzer. When using the dynamic stability as evaluation of anti-rutting standard, we found that the two kinds of experimental methods had a good correlation. And with the increase of temperature,load increasing and asphalt dynamic viscosity decreasing, the dynamic stability decreased in the present nonlinear.According to the domestic situation of high temperature stability of asphalt mixture,tit was determined that the standard of the asphalt mixture dynamic stability with high degree is 2800 times/mm.at the temperature 65℃. According to the test, it was selected that the dynamic stability residual rate of the immersion rutting test and the conventional rutting test of APA as the anti-water damage standard. Also considering other road performance factors, the residual dynamic stability index is chosen as 85%. Summarizing domestic structure depth level and realization level of the project material, the author determined the design index of asphalt mixture structure depth as 0.7mm.According to the experimental result of the he asphalt pavement structural design parameters, structure layer function and needs of the project, we determined the structure layer composition and thickness of structure layer.