Test Research On Fatigue Property Of Double-layer Polyester Fiber Asphalt Concrete Structure

Asphalt pavement has made great development in Chinese road construction due to its comfortable drivability, easy maintenance with the rapid development of China’s national economy. Polyester fiber, as a reinforcing material, can improve the road performance of asphalt pavement and extend its life.The temperature is the main factor of the asphalt pavement’s fatigue performance in the reason of South-North climate differences, and also the replacement of the seasons. It is very significant to study the influence of temperature and polyester fiber content to the fatigue performance of asphalt mixture, in the reason that fatigue cracking are the major structural failure modes in the asphalt pavement.This paper argues the specific crack prevention measures after the analysis of the theory of fatigue cracking of asphalt pavement. Do research on double-layer of asphalt concrete pavement structure and set three temperatures of-5℃,10℃,25℃, three polyester fiber contents of0.1%,0.2%,0.3%, and three stress ratio of0.6,0.7,0.8according to test requirements. In order to study the influence between asphalt-aggregate ratio and Polyester fiber, three kinds of asphalt-aggregate ratio of4.4%,4.8%,5.2%are selected.Polyester fiber is used in the below layer of the structure because fatigue damage is below the layer of asphalt pavement. There are96samples divided in8groups are produced.30samples are used for ultrasonic testing and flexural strength test, and66samples are used for indoor trabecular bending fatigue test. Firstly, double-layer asphalt concrete structures are used for ultrasonic testing and flexural strength test, and then the indoor trabecular bending fatigue test is made on the base of ultrasonic testing and flexural strength test.The study founds that there is a good correlation between flexural strength and velocity. So, the ultrasonic wave velocity can be used for the strength prediction of fatigue sample, the regression equation for the velocity and intensity is: f=0.0009xe0.0022v R2=0.9186(-5℃),f=0.0006xe0.0023v R2=0.9276C10℃),f=0.0034xe00015v R2=0.9083(25℃),f=0.0651xe0.0008v R2=0.9027(0.1%),f=0.1643xe0.0006v R2=0.9090(0.2%),f=0.1127xe0.0007u R2=0.9167(0.3%); Ultrasonic velocity, flexural strength and fatigue life of the asphalt mixture are affected by temperature and the polyester fiber content, which increase with decreasing temperature, increase at beginning and then decrease with polyester fiber content increasing. The performance of double-layer asphalt concrete pavement structure is the best when the polyester fiber content is0.2%and asphalt-aggregate ratio is4.8%. Stress ratio also affects the fatigue life of the asphalt mixture, and the smaller stress ratio the greater fatigue life.The paper shows that there are good social and economic benefits for the polyester fiber asphalt pavement applied to the below layer of the structure, which can delay fatigue cracking of the asphalt pavement. It is great instructed meaning for asphalt pavement design and on-site guidance in the different regions under different temperature conditions, and the base is laid for its promotion of wide range of applications.