Measurement Accuracy Comparison of InSitu Asphalt Pavement Strain Sensors Based on Digital Image Correlation Technique

Abstract:

A method to measure strain distribution on the asphalt mixture surface was developed based upon DIC (digital image correlation) in order to compare the measurement accuracy of insitu asphalt pavement strain sensors. First, the displacement was distinguished at subpixel level using the DIC technique. Then an algorithm to calculate average tensile strain was proposed to eliminate the adverse effect caused by asphalt mixture inhomogeneous deformation in strain measurement. After testing the reliability of the algorithm, the measurement accuracy of two common insitu asphalt pavement strain sensors were calibrated. It was found that the error of the DIC method was less than 12×10-6 at the 90% confidence level, which met the requirement of accuracy comparison. Besides, it was proved that the measurement accuracy could be reflected by the error between the measurement result of the sensors and the method developed in this paper. It was also proved that load type had an influence upon sensor’s accuracy. Utilization of calibration function or eliminatation of the cumulative plastic strain all contributed to the improvement of accuracy.

Key words:pavement engineering; measurement method; accuracy comparison; insitu asphalt pavement strain sensors; digital image correlation