Assessment of K98 subgrade elastic modulus beneath asphalt concrete pavements on expressways using a dynamic loading evice

The elastic modulus at the top of the subgrade is one of the key criteria for acceptance during road construction. It is also an essential parameter to be collected during operation to evaluate the serviceability of the roadway, and to support maintenance planning, upgrading, and expansion of existing roads. However, determining the elastic modulus or other geotechnical parameters of the subgrade is challenging for in-service roads, particularly expressways. To address this issue, non-destructive testing devices have been developed. This paper presents a method for assessing the elastic modulus of the K98 subgrade based on measurement data obtained from a dynamic loading device, and compares the results with laboratory CBR tests to establish a suitable correlation between the elastic modulus and CBR values under specific conditions. The rational combination of these tests not only enhances the reliability of pavement design and performance evaluation but also ensures cost-effectiveness.