Soil compaction specification procedure for desired field strength response

A glacial silty clay was compacted in a field test pad to determine what variables control density and strength and their variabilities. Correlation was attempted to provide a prediction process for the field result. A procedure was identified by which quality assurance and design engineers can interpret and write compaction specifications that insure a desired field strength. Strength is controlled by water content, density, and incompactive effort. Dry density is controlled by water content, compactive effort, and the interaction between them. The quantitative influence of each constituent variable varied with type of equipment. Variabilities of both density and strength are significant. A procedure is presented for this soil which develops a computer tabulation of the variables to allow an estimate of field compacted strength knowing inspection test results. A procedure to allow the design engineer to directly determine his compaction specification to insure a desired strength and its variability is developed.