ABSTRACT
Subgrade layer plays an important role to support the overlying pavement structural layers. To resist permanent deformation and failure under traffic loadings, subgrade soils are compacted to a required maximum density level during the field construction. This paper presents a simple exponential model to estimate subgrade soils density using Ground Penetrating Radar (GPR). The model was developed based on electromagnetic mixing theory to backcalculate subgrade soils density using GPR measurements. The developed model determines a soil’s dielectric constant, considering dielectric and volumetric properties of the three major components of soil: air, water, and solid particles. A series of laboratory tests was conducted on six (6) soil samples at various density levels to validate the estimated densities with the measured ones. The soils density estimated by the new exponential model showed approximately 6% error than soils density measured by sand cone method.
