Standard Test Method for Maximum Media Density for Dead Load Analysis of Vegetative (Green) Roof Systems

Importancia y uso:

5.1 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.

5.2 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.

5.3 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.

5.4 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.

Subcomité:

D08.24

Referida por:

E2398_E2398M-19, E2397_E2397M-19, E2777-20, E2788_E2788M-24

Volúmen:

04.04

Número ICS:

91.060.20 (Roofs)

Palabras clave:

air-filled porosity; green roof; green roof system; maximum density; media; non-capillary porosity; vegetative roofing system; water permeability; water retention;