Evaluation of Granular Density and Moisture Testing

SD2014-12 Compaction Testing of Granular Material was a research project to review current South Dakota Department of Transportation (SDDOT) compaction control methods and determine whether more appropriate methods were available. Two possible improvements were recommended as a result of this research. The first recommendation was to adopt moisture density curves made specifically for the materials SDDOT uses. A family of moisture/density curves was developed from historical SDDOT compaction tests of base and subbase materials to replace the currently used Ohio Curves, which do not apply to granular material and are being phased out by many state transportation agencies. Another recommendation was to change the testing method from relative compaction to a strength-based procedure using the Dynamic Cone Penetrometer (DCP). The DCP testing was based on specifications from Minnesota Department of Transportation (MnDOT). Finally, SD2014-12 recommended full-scale side-by-side tests on pilot projects prior to adopting either of these techniques. The study’s technical panel thought it advisable to verify the applicability of the South Dakota moisture-density curves over a full range of materials and geographical areas. The panel also recommended parallel testing of the DCP to: verify correlation of strength with density; evaluate the speed, convenience, and safety of the test procedure; identify operational limits on its use; and determine whether adjustments to MnDOT specifications are needed in South Dakota. The purpose of this research will be to design and execute an effective evaluation plan for the South Dakota moisture/density curves and the DCP and to recommend how they can be best used in South Dakota. The research objectives are to: (1) Design a field test program that will provide side-by-side comparison of the SDDOT moisture/density curves and the DCP test to current compaction testing methods during the 2020 construction season. (2) Based on results of the side-by-side comparison, evaluate the suitability of the SDDOT moisture/density curves and the DCP test as replacements for current granular material compaction acceptance. (3) Recommend specifications for using the SDDOT moisture/density curves and the DCP test in construction involving granular material compaction.