School of Ecosystem and Forest Sciences, Faculty of Science, The University of Melbourne, 500, Yarra Boulevard, Richmond, Victoria, 3121, Australia.
School of Ecosystem and Forest Sciences, Faculty of Science, The University of Melbourne, 500, Yarra Boulevard, Richmond, Victoria, 3121, Australia.
J Environ Manage. 2020 May 1;261:110206. doi: 10.1016/j.jenvman.2020.110206. Epub 2020 Feb 1.
Green roofs are expanding internationally due to the well documented benefits they provide for buildings and cities. This requires transferable knowledge of the technological aspects influencing green roof design, particularly substrate properties. However, this is made difficult due to differences in substrate testing methods referred to in green roof guidelines and standards. Therefore, we tested a green roof substrate using laboratory-based methods from European (FLL), North American (ASTM) and Australian (AS) green roof guidelines and standards to determine how these methods vary in characterising substrate physical properties (bulk density, water permeability and water holding capacity at field capacity (WHC)). Further, we compared the results from the laboratory-based methods with measures of bulk density and WHC in green roof platforms to determine whether standard methods accurately represent substrate properties in-situ. Results from the standard test methods varied due to differences in sample compaction. The standard test methods that employ Proctor hammer compaction (FLL and ASTM) had greater bulk density (at field capacity and dry) and lower water permeability than Australian standard methods that employ free-fall compaction. WHC did not differ among the standard methods. The Australian standard method better reflected bulk density at field capacity and WHC of the substrate under in-situ green roof conditions. For mineral based substrates, our results suggest that for the FLL and ASTM testing methods, a single Proctor hammer drop will produce a degree of sample compaction equivalent to the free-fall method (AS) and be more representative of bulk density in-situ. Subtle changes in testing procedures would allow for more direct comparison of substrate properties between standard methods and help enable the international transfer of knowledge for substrate design.
绿色屋顶在国际上的应用日益广泛，这是因为它们为建筑物和城市带来了诸多益处，这些益处已被充分证实。这就需要将影响绿色屋顶设计的技术方面的知识（尤其是基质特性方面的知识）进行转化。然而，由于绿色屋顶指南和标准中提到的基质测试方法存在差异，这一过程变得颇具难度。因此，我们使用来自欧洲（FLL）、北美（ASTM）和澳大利亚（AS）绿色屋顶指南和标准的基于实验室的方法对一种绿色屋顶基质进行了测试，以确定这些方法在描述基质物理特性（体密度、透水性和田间持水量（WHC））方面的差异。此外，我们还将实验室方法的结果与绿色屋顶平台的体密度和 WHC 测量值进行了比较，以确定标准方法是否能准确地反映基质的现场特性。由于样品压实度的差异，标准测试方法的结果也有所不同。采用 Proctor 夯击压实的标准测试方法（FLL 和 ASTM）的体密度（田间持水量和干燥时）较高，透水性较低，而采用自由落体压实的澳大利亚标准方法则相反。标准方法的 WHC 没有差异。澳大利亚标准方法更能反映现场绿色屋顶条件下基质的田间持水量和体密度。对于基于矿物质的基质，我们的研究结果表明，对于 FLL 和 ASTM 测试方法，单次 Proctor 夯击产生的样品压实度相当于自由落体方法（AS），并且更能代表现场的体密度。测试程序的细微变化将允许在标准方法之间更直接地比较基质特性，有助于促进基质设计方面的国际知识转移。
