ASTM D6539-13
采用流动空气测量未饱和多孔材料渗透性的标准试验方法

Standard Test Method for Measurement of the Permeability of Unsaturated Porous Materials by Flowing Air

标准号

ASTM D6539-13

发布

2013年

发布单位

美国材料与试验协会

当前最新

ASTM D6539-13

 

 

引用标准

ASTM D1557 ASTM D2216 ASTM D3550 ASTM D3740 ASTM D4220 ASTM D4525 ASTM D4564 ASTM D4753 ASTM D4767 ASTM D5084 ASTM D5856 ASTM D6026 ASTM D653 ASTM D698 ASTM E1 ASTM E145 ASTM E2251

适用范围

4.1 This test method applies to the one-dimensional laminar (viscous) flow of air in porous materials such as soil.

Note 1—This test method deals with porous materials with both gaseous (air) and liquid (pore water) mobile fluids: The liquid phase is much less compressible, has a higher viscosity, and is much more tightly bound to the solid phase by chemical forces. The assumption of single-phase flow may still be presumed to be valid since the test gradient ensuring the conditions of laminar flow may be low enough that flow of the liquid phase is negligible.

4.2 The degree of saturation of the specimen shall be less than that which would produce significant internal transport of pore water or alter the continuity of air voids under the applied gradients. The maximum permissible degree of saturation must be evaluated by an experienced analyst. In no instance shall the specimen be so saturated that pore water appears at the exit of the permeameter cell during the test.

4.3 This test method is based on the assumption that the rate of mass flow through the specimen is constant with time.

Note 2—When a specimen contains volatile materials this assumption is violated. The mass of gas flowing out will be greater than that flowing in, the gradient cannot be determined and the test may become meaningless. Such specimens pose special problems and must be decontaminated before analysis in order to minimize health and safety concerns and to prevent contamination of the test apparatus.

4.4 The permeability of porous materials may be strongly dependent on a variety of physical properties including the void ratio, the degree of saturation, and percent and direction of compaction. It is beyond the scope of this test method to elaborate upon these dependencies. Rather, this test method is intended to be a measurement technique for determining the permeability under a certain set of laboratory conditions. It is the responsibility of the test requestor to specify which soil parameters must be controlled to ensure a valid extension of the test results to field conditions.

4.5 Calculation of the permeability using Darcy’s law requires laminar flow conditions through the soil specimen. The conditions for laminar flow shall be evaluated by plotting the volumetric flow rate of air through the specimen against the pressure drop across the specimen. If the individual test points lie within 25 % of a straight line passing through the origin, then laminar flow conditions are present and Darcy's law may be used to calculate the permeability.

Note 3—The permeability calculated using this standard is valid only when the degree of saturation does not change over time. Long measurement times associated with the use of bubble meters and manometers may indirectly lead to variability when measuring flow versus pressure drop (see 8.2) due to evaporation. The recommended use of digital electronic flow and pressure sensors leads to considerably reduced measurement times because the user can quickly determine by inspection when a steady state......

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