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Standard Test Method for Maximum Media Density for Dead Load Analysis of Vegetative (Green) Roof Systems 植物(绿色)屋顶系统的负荷分析最大介质密度的标准测试方法
发布日期: 2019-02-01
1.1 本试验方法涵盖了为估算绿色屋顶组件的最大恒载而确定最大介质密度的程序。该方法还提供了在最大介质密度下测量的含水量、充气孔隙度和透水性。 1.2 此程序适用于包含不超过30的绿色屋顶介质 % 使用试验方法中所述的燃烧损失测量的有机材料 E177 ,试验方法C。试样应为根据试验方法制备的散装烘干样品 E177 ,试验方法A。 1.3 本程序中测量的最大介质密度和相关含水量适用于饱和点附近的排水条件。 1.4 该测试方法旨在模拟屋顶绿化中的垂直渗滤率。 1.5 以国际单位制或英寸-磅单位表示的数值应单独视为标准值。每个系统中规定的值可能不是精确的等效值;因此,每个系统应相互独立使用。将两个系统的值合并可能会导致不符合标准。 1.6 本标准并非旨在解决与其使用相关的所有安全问题(如有)。本标准的用户有责任制定适当的安全、健康和环境实践,并在使用前确定监管限制的适用性。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒(TBT)委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 本试验方法描述了简单的实验室方法,提供了关键介质特性的可重复测量,并允许在不同介质材料之间进行直接比较。 5.2 混合介质材料的密度将根据其压实程度以及允许材料水合和随后排水的时间长度而变化。 大多数屋顶绿化材料具有吸收和保持水分的大容量。此外,水分将在水化循环后逐渐从介质中排出。在此过程中测量的最大介质密度接近理论饱和点的密度。 5.3 测量土壤毛细水分关系的现有方法(试验方法 D2325 )依靠样品制备程序(测试方法 D698 )这与放置绿色屋顶介质材料的相关条件不一致。该程序旨在提供一种可重复的实验室程序,用于在更接近于绿化屋顶现场条件的条件下预测最大介质密度、含水量、充气孔隙度和透水性。 5.4 该测试方法对绿色屋顶设计师的价值在于,它为估计结构荷载提供了最大可能介质密度(在排水条件下)的客观测量。它还提供了一种估算原位介质透水性下限的方法。在考虑屋顶绿化的排水条件时,后一个值很重要。最后,最大介质保水性已被证明是绿色屋顶介质保水性能的有用指标。
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 either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the 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, health, and environmental practices and to determine the applicability of regulatory limitations prior to use. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 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.
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