Evaluation of three nondestructive testing techniques for quality assessment of asphalt pavements

This study evaluates three nondestructive testing (NDT) techniques for quality assessment of asphalt pavements. The three NDT techniques examined include an electromagnetic density gauge, a dynamic stiffness gauge, and geophysical surface wave tests for measuring modulus. In-situ NDT tests were carried out for four representative paving projects covering a range of asphalt mixes and traffic loads, and cores were extracted at the centre of each NDT testing location for laboratory measurement of density and modulus. A comprehensive correlation analysis was carried out to examine the performance of each NDT method for quantifying the quality of the asphalt pavements. The in-situ density had a low correlation with the laboratory density and was not sensitive to variations in temperature and asphalt mix type. The in-situ stiffness measured on the asphalt mixtures several hours after paving had a high correlation with the in-situ dynamic modulus and laboratory density, and is therefore recommended as a quantitative property for quality control. Among the three NDT measurements, the in-situ modulus was most sensitive to variations in temperature and asphalt mix type. After correction for temperature effects, the corrected modulus is recommended as a quantitative property for quality assurance.