ABSTRACT
The tensile strain at the bottom of asphalt concrete is well accepted as one of key factors influencing pavement performance, as it is directly related to fatigue cracking. This paper presents a procedure to estimate tensile strain at the bottom of asphalt layers using the measured dynamic tensile strain and the deflection basin response from Falling Weight Deflectometer (FWD) tests. Dynamic tensile strain sensors were installed during the construction and strain measurements were made in conjunction with FWD loadings. The experimental tests were performed in three separate test sections with semi-rigid base asphalt concrete (AC) pavement, inverted asphalt pavement structure, and compound asphalt pavement structure, respectively, in a recent constructed motorway in Sichuan Province, China. Firstly, the influences of the pavement types, temperature conditions, and load levels on the measured dynamic tensile strain at the bottom of asphalt layer were identified. Then, this study analyzed the correlation of the measured dynamic tensile strain and the corresponding deflection basin responses by using the grey relation entropy method. The results suggested a highly significant correlation. Finally, a group of regression models to estimate the dynamic tensile strain for various types of asphalt concrete pavement was proposed by using the measured deflection basin responses from FWD tests.
