Senior engineerMember of ASTM, Law Engineering Testing Co., Miami, Fla.
Chief soils engineer, Bechtel, Inc., San Francisco, Calif.
During the course of a large earthwork project in Georgia, six test fills were constructed to study placement and compaction procedures. Several density testing techniques used in the quality control testing program were compared. A laboratory compaction test was performed at each field density test location to eliminate the need to select the appropriate compaction curve from a family of curves. More than 180 nuclear density, sand cone, and laboratory compaction tests were compared. Two soil types, both sands, were involved in the test program. The effects of gradation, compaction, mold size, depth of density test, and type of nuclear device were investigated. Variables in construction procedures included type of equipment, number of passes, lift thickness, and soil type. Following a statistical evaluation it was concluded that (1) oven moisture contents were consistently lower than nuclear moistures, (2) nuclear wet densities were always less than sand cone densities, and (3) the sand cone density test method yielded a 5% higher compaction when compared to the nuclear test method.
Paper ID: GTJ10459J