01029828

Component

The soil air voids method represents an alternate approach to the traditional Proctor method of field compaction control. The evaluation procedure is based on the premise that the future performance of a compacted layer of soil can be evaluated by comparing the measured air voids to a predetermined limiting value. In theory, a field inspector can rapidly determine if a soil layer meets the specified compaction criteria without obtaining a soil sample for laboratory Proctor compaction testing. Recently, there has been renewed interest in this approach by state departments of transportation because of its timesaving benefits and relative simplicity. The results of this study indicate the air voids method provides an indirect check on the dry density of the compacted layer; however, the soil water content is not directly assessed during the field evaluation. Using results from laboratory and field tests, examples are provided of problems that could occur with certain soil types if inherent water content limits are relied upon during compaction. Potential problems include excessive shrink or swell, excessive settlement, reduced bearing capacity, and stability problems due to high excess pore water pressures. It was demonstrated in this study that some materials could pass the air voids test, but fail the conventional Proctor criteria (for example, 95% of the Proctor maximum dry density). This condition can be identified in the laboratory, prior to construction, if Proctor compaction and specific gravity tests are conducted and the relationship between air voids and percent relative compaction is carefully established.

01020180

06-0320

English

21p

2006

Transportation Research Board 85th Annual Meeting

CD-ROM

Figures (9) ; References; Tables (1)

Air voids; Compacted soils; Dry density; Moisture content; Pore water pressures; Soil compaction; Soil tests; Soils; Stability (Mechanics)

Proctor compaction test; Soil air voids method

Geotechnology; Highways; I42: Soil Mechanics

Transportation Research Board Annual Meeting 2006 Paper #06-0320

TRIS, TRB

Mar 3 2006 10:19AM