Proctor Compaction Testing; Research rept

摘要

The Nebraska Department of Roads specifies the standard Proctor test (ASTM D 698/AASHTO T 99) as the method of estimating maximum dry density and optimum moisture content for subgrades and compacted fill sections. The standard Proctor test approximates maximum soil density capable of being produced by early generations of construction equipment. Laboratory procedures known as the modified Proctor test (ASTM D 1557/AASHTO T 180) have been developed that accurately estimate the greater densities available from the compaction efforts of modern construction equipment. For the same soil, the optimum moisture content (OMC) for a modified Proctor test is usually less than OMC for a standard Proctor test while maximum dry density is higher. This research consisted of performing both standard and modified Proctors tests on representative groups of Nebraska soils and then evaluating and comparing the test results. A table with formula to convert standard Proctor dry densities and moisture contents to modified Proctor specifications and vice versa was produced. Sample calculations estimating the cost savings from compacting to modified versus standard Proctor specifications were included as was a chart showing the compaction standards currently used by state transportation agencies.