Ground-Penetrating Radar for Cold In-Place Recycled Road Systems

Grain transportation rationalization, economic diversification, and value-added initiatives within the Saskatchewan economy has increased, and will continue to increase, commercial truck traffic on many Saskatchewan roads. As a result, the Saskatchewan Department of Highways and Transportation is investigating cold in-place recycling as a rehabilitation alternative for strengthening thin-paved roads. However, different construction practices and years of maintenance and rehabilitation have led to many of these thin-paved roads having a variable structural composition. The effect of in situ variability on cold in-place recycle designs is further exacerbated by the inherent sensitivity of stabilizers such as asphalt emulsion, foamed asphalt, cementitious blends, and/or concentrated chemicals when integrated into different road materials. As a result, the materials and structural design of cold in-place recycled thin-paved road systems can be highly uncertain. Ground-penetrating radar has been identified as an engineering diagnostic tool that can accurately quantify in situ structural composition and help reduce the uncertainty associated with the material and structural design of cold in-place recycled road systems. This paper summarizes the principles of ground-penetrating radar, discusses the use of ground-penetrating radar as an engineering diagnostic tool for cold in-place recycling of thin-paved roads, and presents two pilot case studies undertaken by the Saskatchewan Department of Highways and Transportation that demonstrate the capability of ground-penetrating radar to mitigate the uncertainty associated with cold in-place recycled road systems.