A new ASTM International standard will aid in the selection of lightweight aggregate best suited for use in the design and construction of vegetative roof systems. 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, was developed by Subcommittee E60.01 on Buildings and Construction, part of ASTM International Committee E60 on Sustainability.
Specifiers, blenders and users of lightweight growing media for green roof applications will be the primary users of E2788.
According to Chuck Friedrich, an E60.01 member, 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.
“E2788 can be used to select the size and type of lightweight aggregate best suited for a project,” says Friedrich, Carolina Stalite Co. “The selection will be determined by local availability, but the new standard gives a broad scope of the properties will allow most ESCS products in each region to meet the specification.”
According to Friedrich, 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, which has been determined to be the most crucial physical property needed for green roofs.
All interested parties are invited to join the ongoing standards developing activities of E60.01. Chief among its current projects is the development of a proposed new standard, WK25385, Guide for Vegetative (Green) Roof Systems, which will identify terminology, principles and fundamental concepts, including those related to sustainability, technical requirements of construction, and types of vegetated green roof systems or green roofs used on buildings.