National Center for Wood Transportation Structures

About the research

Changes in pavement foundation moisture levels, driven by environmental factors such as heavy rainfall, freeze-thaw cycles, and fluctuations in the groundwater table, can significantly affect the performance of Minnesota’s pavements in both the short and long term. Ground-penetrating radar (GPR) offers a non-invasive, portable, and cost-effective solution for rapidly assessing large road segments and detecting subsurface moisture levels, especially when compared to traditional methods such as in-place sensors or indirect techniques like the falling weight deflectometer (FWD). The advantages of GPR technology are particularly beneficial for local road authorities, who often face financial constraints and limited staff, by enabling prompt assessment of moisture conditions in critical pavement areas. The objective of this study is to enhance the validation and implementation of GPR-based pavement moisture assessments on actual low-volume roads. Specifically, this involves evaluating the ability of GPR to efficiently survey large pavement areas, monitor moisture, and identify sections potentially impacted by drainage issues. These objectives will be accomplished through GPR surveys on test sections of low-volume roads equipped with in-situ moisture sensors. The data collected will be analyzed and compared. An automatic detection algorithm will be developed to evaluate moisture variation in ground material within unbound pavement layers. This algorithm will be validated and implemented as software, featuring modularized, optimized code, a graphical user interface (GUI), and an accompanying user manual. The successful outcomes of this study will provide a set of implementation recommendations aimed at improving decision support tools and technical guidelines for assessing moisture fluctuations in Minnesota’s low-volume roads.