A study was undertaken to determine the drainability characteristics of several types of unbound granular materials that are used in pavement bases. From the literature, testing concerns were identified and analyzed. Hydraulic conductivity and effective porosity were determined for aggregates from two sources of crushed stone and two sources of gravel. For each material two open gradations were tested in a rigid wall permeameter. One dense gradation of each material, at two levels of compaction, was tested in a flexible wall permeameter as well. Efforts were made to reduce possible flow along the sides of the rigid wall permeameter and to eliminate problems with air bubbles. The average hydraulic conductivities for the open and dense-graded materials were 3.6 \* 10-1 and 3.0 \* 10-4 cm/s (1,021 and 0.85 ft/d), respectively. The effective porosities for the open and dense-graded materials were 68 and 27% of the nominal porosities, respectively. Four regression equations representing a wide range of hydraulic conductivity were developed to estimate hydraulic conductivity based on the results of this study and others reported in the literature.
- Granular Materials,
- Hydraulic Conductivity,
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