Experimental Study On Mechanical Response Of Asphalt Pavement Including LSAM Base

A lot of vehicles running on expressway in China are heavy axle-load trucks, most of which are severely over-loaded. Nearly all of the expressways are covered with asphalt pavement including a semi-rigid base for economic reason. Therefore damage of rutting and reflection cracks is usually observed in their early service period. It has been proved by some researches that an asphalt pavement including large-stone asphalt mixes (LSAM) base is expected to overcome the problem. But it has not been accepted widely in practice in China because the research until nowadays is not efficiently. For this reason, the mechanical response of asphalt pavement including LSAM base is studied by field experiment.The experimental LSAM pavement which is 600 m long was constructed in Wuhan-Ezhou Expressway. It includes three sections named respectively as A, B and C. The structure layers of section A is:46 cm cement gravel+10 cm ATB-30+8 cm AC-25+6 cm AC-20+4 cm AC-13. Beside having the same layers of section A, section B has a glass fiber grid at the interface of cement gravel and ATB-30. Section C consists of 44 cm cement gravel+20 cm ATB-30+6 cm AC-20+4 cm AC-13.Pressure cells were placed both at the top of soil subgrade and at the top of the cement gravel. At the bottom of ATB-30 and the bottom of AC-25 (for section A and section B) or AC-20 (for section C) fiber grating based (FBG) sensors were embedded for strain measurement.Static load tests were carried out by loading plate. A series of traffic load tests were demonstrated by moving trucks under different tire loads. During the static and traffic load tests, the internal pressures and strains of the pavement structure were both measured. Based the analysis of the test data, the mechanical properties of asphalt pavement including LSAM base is discussed. A FEM model which gives a result coinciding with the field experiment, is then proposed by ANSYS Program to conduct a detail analysis on the response of this kind of pavement under traffic loading. The experimental and numerical analysis results prove that asphalt pavement including LSAM base has a good performance against rutting and reflection cracking.