DRAINAGE CHARACTERISTICS OF BASE COURSE MATERIALS LABORATORY INVESTIGATION.
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS
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A laboratory investigation of the effects of high degrees of compaction on the drainage characteristics i.e., permeability and effective porosity of coarse-grained base course materials was made to provide data for improving subsurface drainage design criteria. The investigation included the development of constant-head permeability test procedures for determining the coefficient of permeability of coarse-grained materials. In developing the test procedures, the effects of the following factors on permeability test results were investigated compaction method, specimen size, compaction water content, method of saturating specimen, hydraulic gradient, rearrangement of particles, and temperature of the permeating water. Specimens of four gradations of base course materials were tested at densities ranging between 90 and 110 percent of their respective CE-55 maximum dry densities modified AASHO. The results of the investigation indicated that the permeability of the three coarser grained materials varied with density and hydraulic gradient, except at the higher densities. The permeability of the fourth finest material varied with density but not with hydraulic gradient. Results of effective porosity tests indicated that the effective porosity of a material decreases with increase in density and with increase in percentage of fines. The results of the investigation indicated that when the materials containing 5 percent or more of material passing the No. 200 sieve are compacted to high densities, they generally will not meet established drainage criteria. Author
- Soil Mechanics
- Construction Equipment, Materials and Supplies