Use of NDT systems to investigate pavement reconstruction needs and improve maintenance treatment decision-making

The objective is to improve the accuracy of the test results and establish a maintenance treatment decision-making system using the non-destructive testing (NDT) technology. Firstly, the evaluation unit length was theoretically determined and statistically verified. Secondly, the test frequency of falling weight deflector (FWD) test was statistically analysed and the deflection acceptance criterionwas obtained based on the probability density distribution curve. Meanwhile, the relationship between the FWD deflection and the pavement internal damage obtained by drilling was analysed. Subsequently, the test parameters of the three-dimensional ground-penetrating radar (3D GPR) were optimised by using the non-reference image quality assessing technology. Followed, pavement internal damage index of GPR was proposed for locating the defect structural layer. Lastly, the decision-making systemwas established. Results showed that the suitable evaluation unit length is 20 m, the deflection test frequency is no more than 10 m/point, the deflection accept criterion is 29.5 (0.01 mm) with 95% reliability and the optimal detection parameters of GPR is 1 cm, 10 µs and 25 ns respectively. The established decision-making system fully considering the surface and the interior conditions as well as the functional and structural conditions can effectively guide the maintenance plan formulation for similar reconstruction and expansion projects.