Significance and Use
This test method describes simple laboratory methods that provide reproducible measurements of critical media properties, and permit direct comparisons to be made between different media materials.
The density of mixed media materials will vary depending on the degree to which they are subjected to compaction and the length of time that the material is allowed to hydrate and subsequently drain. Most green roof media materials have a large capacity to absorb and retain moisture. Furthermore, moisture will drain gradually from the media following a hydration cycle. The maximum media density measured in this procedure approaches the density at the theoretical saturation point.
Existing methods for measuring the capillary-moisture relationship for soils (Test Method D2325) rely on sample preparation procedures (Test Methods D698) that are not consistent with the conditions associated with the placement of green roof media materials. This procedure is intended to provide a reproducible laboratory procedure for predicting the maximum media density, moisture content, air-filled porosity, and water permeability under conditions that more closely replicate field conditions on green roofs.
The value of this test method to the green roof designer is that it provides an objective measure of maximum probable media density (under drained conditions) for estimating structural loads. It also provides a method for estimating the lower limit for the water permeability of the in-place media. This latter value is important when considering drainage conditions in green roofs. Finally, the maximum media water retention has been shown to be a useful indicator of the moisture retention properties of green roof media.
1.1 This test method covers a procedure for determining the maximum media density for purposes of estimating the maximum dead load for green roof assemblies. The method also provides a measure of the moisture content, the air-filled porosity, and the water permeability measured at the maximum media density.
1.2 This procedure is suitable for green roof media that contain no more than 30 % organic material as measured using the loss on ignition, as described in Test Methods E177, Test Method C. The test specimen should be a bulk oven-dried sample prepared according to Test Methods E177, Test Method A.
1.3 The maximum media density and associated moisture content measured in this procedure applies to drained conditions near the saturation point.
1.4 The test method is intended to emulate vertical percolation rates for water in green roofs.
1.5 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
D698 Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12 400 ft-lbf/ft3 (600 kN-m/m3))
D2216 Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
D2325 Test Method for Capillary-Moisture Relationships for Coarse- and Medium-Textured Soils by Porous-Plate Apparatus
D2947 Test Method for Screen Analysis of Asbestos Fibers
E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E631 Terminology of Building Constructions
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E2114 Terminology for Sustainability Relative to the Performance of Buildings
air-filled porosity; green roof; green roof system; maximum density; media; non-capillary porosity; water permeability; water retention; vegetative roofing system: Density; Green roof systems; Media; Sustainability; Water retention; Dead load testing;
ICS Number Code 91.060.20 (Roofs)
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Citing ASTM Standards
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