AbstractAsphalt pavement contains dynamically changing moisture, and the movement of this moisture will change the relative humidity of the pavement, thereby affecting the dielectric properties of the asphalt mixture. To improve the detection accuracy of nondestructive testing equipment and quantify the influence of relative humidity and frequency on the dielectric properties of asphalt mixtures, a dielectric composite model of asphalt mixtures based on relative humidity and frequency was established through theoretical deduction. The relative dielectric constant and dielectric loss of two asphalt mixtures were evaluated under different relative humidity and frequency conditions to verify the accuracy and reliability of the proposed model. The obtained goodness-of-fit verified wide applicability of the model. To realize the unification of the detection data under different relative humidity and frequency conditions, the relative humidity–frequency equivalence principle was established, and feasibility was verified in experiments that displayed strong applicability within a certain relative humidity and frequency range, thus providing a basis for realizing the conversion of the test results of different nondestructive testing equipment.