ASTM D6539 Permeability of Unsaturated Porous Materials

Scope:

The one-dimensional laminar (viscous) flow of air in porous materials such as soil is tested using this method. The purpose of this test method is to aid with soil remediation, soil vapor extraction, air sparging, back-filling of soils in utility trenches, and other comparable engineering activities. Under the applied gradients, the degree of saturation of the specimen must be less than that which would cause considerable internal pore water movement or disrupt the continuity of air spaces. The assumption behind ASTM D6539 is that the mass flow rate through the specimen remains constant over time. Instead, this test method is meant to be used as a measurement tool for determining permeability under specific laboratory settings.

Read More :- ASTM D 5084-Saturated Porous Materials

Procedure:

The following test methods are described in ASTM D6539:

Specimen size

A right circular cylinder with a recommended diameter of at least 51 mm is required as the test specimen. The length of the ASTM D6539 test specimen should be greater than 1.3 times its diameter.

Data

QAV = Q × PS ÷ (PI + PB – ∆P/2) × T ÷TS

Where: 

QAV is the average volumetric flow rate of air at the average pressure and temperature of the laboratory during testing, m³/s, 

Q is the flow of air into the specimen at STP, m³/s, 

PB is the barometric pressure at the time of testing, Pa, 

PI is the specimen inlet gauge pressure, Pa, 

PS is the reference pressure at STP, Pa, 

∆P is the pressure drop across the specimen, Pa, 

TS is the reference temperature at STP, Kelvin, and 

T is the test temperature, Kelvin.

Conclusion:

The permeability coefficient for air passage through unsaturated porous materials is determined using the test method ASTM D6539.