by Shane Henson — August 3, 2012—ASTM International, a developer of international standards for materials, products, systems and services used in construction, manufacturing and transportation, recently announced a new standard that it says will aid in the selection of lightweight aggregate best suited for use in the design and construction of vegetative roof systems, or “green roofs.” Green roof technologies can provide significant social, economic and environmental benefits, particularly in cities.
Specifiers, blenders and end users of lightweight growing media for green roof applications will be the primary users of the new ASTM E2788, Specification for Use of Expanded Shale, Clay and Slate (ESCS) as a Mineral Component in the Growing Media and Drainage Layer for Vegetative (Green) Roof Systems, says ASTM. According to Chuck Friedrich, an E60.01 member, ASTM E2788 provides typical gradations, physical and chemical properties of the rotary kiln expanded lightweight aggregates that can be used as a lightweight fill, drainage material or as growing media component for green roofs.
“ASTM E2788 can be used to select the size and type of lightweight aggregate best suited for a project,” says Friedrich. “The selection will be determined by local availability, but the new standard gives a broad scope of the properties that will allow most ESCS products in each region to meet the specification.”
Friedrich notes that ESCS is regularly manufactured for use in the lightweight concrete industry but is also desirable for most green roof media because its availability, consistency and physical properties meet the requirements of most green roof media specifications. ESCS materials also contribute to good drainage, he says, which has been determined to be the most crucial physical property needed for green roofs.
For an explanation of the public, private and design-based benefits of green roofs, visit the Green Roofs for Healthy Cities Green Roof Benefits Web page.
