Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange
Abstract
A majority of roads in the state of SD are low volume roads (LVRs). The SDDOT has developed simplified methods for LVR pavement thickness selection. These guides allow users to obtain recommended asphalt surfacing and base course layer thickness based on the subgrade support and the average daily traffic (ADT) of the road. The main objective of this study is to relate the surface condition of LVRs to their ADT, layer thicknesses, foundation material properties, and maintenance. A secondary objective was to evaluate if the Dynamic Cone Penetrometer (DCP) is an acceptable tool in determining the subgrade support by using it to measure the penetration resistances of the foundation layers. A total of 16 different asphalt surfaced LVRs across SD were tested. The construction and maintenance histories of the roads was obtained. The performance of the roads was evaluated based on the surface condition of the pavement. Field tests were performed to obtain the layer thicknesses, DCP Penetration Index, and samples were obtained for laboratory testing. The laboratory testing included moisture content, liquid limit, plastic limit, and gradation tests. The results of the tests were used to compare the layer thicknesses and material properties to both the performance of the roads and the suggested thicknesses and material specifications from the SDDOT guides. Based on the analysis, it was determined that the DCP test did not provide an adequate measure of the subgrade soil support to be used in the SDDOT Rural Road Design Guide. It was also determined that the layer thicknesses, material quality, and maintenance schedule all contribute to the performance of asphalt surfaced LVRs. They have the greatest positive impact on a road’s performance when all three of these components satisfy the guidelines in the SDDOT Rural Road Design Guide
