Findings: The performance of asphalt concrete (AC) shoulders adjacent to Portland cement concrete (PCC)
pavements has been extremely variable throughout South Dakota, with relatively good performance on some projects and severe shoulder subsidence and shoulder joint seal failure occurring on others. The factors behind poor shoulder performance may be directly related to shoulder design and construction, combined with regional climatic and topographical features.
The research performed in this study sought to better define the causes of shoulder subsidence and joint seal failure, and to develop and implement a field study that tests the effectiveness of various design strategies and construction practices in reducing or minimizing settlement and seal failure. In the study, a total of 29 in-service shoulder structures located in the eastern half of the state were surveyed for condition and tested for load response characteristics using non-destructive deflection testing (NDT) techniques. The observations and resulting data were then used to formulate a set of shoulder design/construction strategies that could be tested as part of an actual paving project.
Subsequently, a total of 11 different shoulder strategies were included in a mainline PCC paving
project located on SD 37, north of Parkston. The construction of the test shoulders in fall 2001 were carefully monitored, and condition surveys and NDT testing of the shoulder sections were conducted at periods of 7 and 12 months following construction. This report discusses the results of the entire research effort and the recommendations made to the South Dakota DOT concerning their AC shoulder design and construction practices.