The nuclear density gauge has been the standard soil compaction acceptance method for the Missouri Department of Transportation (MoDOT) for several decades. However, the cost of licensing, security, transport protocol and training imposed by the federal government have caused MoDot to question whether it remains a cost effective testing technology.. Nuclear density testing's rapidity and accuracy has been crucial in enabling MoDOT inspectors to keep contractor grading processes on schedule. But, in the last two years MoDOT's Quality Management program has shifted the bulk of testing requirements to the contractor, reducing the need for MoDOT inspection on grading projects. As a result, MoDOT is investigating compaction testing alternatives to the nuclear density gauge which can provide the necessary results at a lower life cycle cost. The investigation comprised a comprehensive review of previous research into compaction testing alternative as well as key findings and gaps in research. This led to the purchase of XX pieces of alternative test equipment which were employed simultaneously alongside the nuclear density gauge on four large structural fill projects. The field testing yielded a set of comparable test results taken at the same time, in roughly the same location, and under the same environmental conditions, and arguably making this research the most comprehensive study of compaction testing technology on record.

The dissertation discusses MoDOT's Quality Management program's development and links to its origin in Design-Build project best practices, which provided the motivation to seek alternatives to the nuclear density gauge. Life Cycle Cost Analysis and Cost Index theory was utilized in comparing the compaction testing alternatives and presenting present cost per compaction test for the Department. For MoDOT project sites, linear and multiple regression analyses were developed to determine if correlations existed between soil density and associated modulus or Clegg Impact Values. Lastly, an assessment of the repeatability and reproducibility of the light weight deflectometer and the dynamic cone penetrometer on a project site was completed with three distinct statistical analytical methods. The data presented herein can be integral elements in MoDOT's decision to eliminate or keep the nuclear density gauge.