Test Method Title
Standard Test Methods for Water Permeability of Geotextiles by Permittivity
Reference Number
ASTM D4491
Material
Geotextile
Test Property
Permittivity, Permeability
Description of Test
Permittivity is determined by either a constant or falling head test. Constant Head Test—A head of 50 mm (2 in.) of water is maintained on the specimen throughout the duration of the test. The quantity of flow is measured versus time. The constant head test is used when the flow rate of water through the geotextile is so large that it is difficult to obtain readings of head change versus time in the falling head test. Falling Head Test—A column of water is allowed to flow through the geotextile and readings of head changes versus time are taken. The flow rate of water through the geotextile must be slow enough to obtain accurate readings.
Number of Test Specimens
4
Test Specimen Size
2.2" diameter
Keywords
flow rate, permeability, permittivity