GPR experimental evaluation of subgrade soil characteristics for rehabilitation of roads

Abstract

One of the most crucial problem in roads rehabilitation regards the pavement damage. Usually it is easy to localize the damage, but it is always difficult to identify the causes. The rehabilitation can be compromised, if the cause is not removed. The GPR technique is used by many Agencies involved in roads management. It is nondestructive and it is promising for soil characteristics interpretation, such as moisture or density. A classification of pavement damage, based on GPR analysis, is already performed and experimentally validated. The causes of damage are often referable to water intrusion in subgrade or clay intrusion in sandy subgrade. This is why we principally investigate how the moisture and the soil density influence the dielectric constant. The outcomes of a laboratory experimental survey are here discussed. Different soils have been considered. The GPR responses of each soil have been investigated, considering different moistures. The dielectric properties are highly correlated with the water content and the water status in soil. A significant correlation between dielectric properties and soil density is shown; this correlation is not so relevant as the previous. Any generalization is not reliable, but the study proves that the GPR evaluation of subgrade characteristics is possible.