ASTM E2788/E2788M-24

Standard Specification for Use of Expanded Shale, Clay, and Slate (ESCS) as a Mineral Component in the Growing Media and the Drainage Layer for Vegetative (Green) Roof Systems

ABSTRACT
This specification covers the quality and grading of expanded shale, clay and slate (ESCS) for use as a mineral component of growing media and drainage layer for extensive and intensive vegetative (green) roof systems. ESCS is a lightweight, highly porous and low-density ceramic material produced by expanding and vitrifying select shale, clay or slate in a rotary kiln. The requirements are intended to cover only materials having normal or average gradation characteristics. This specification also describes the materials and manufacture, as well as physical and chemical properties.
SCOPE
1.1 This specification covers the quality and grading of the following materials for use as a mineral component of growing media and drainage layer for extensive and intensive vegetative (green) roof systems. The requirements are intended to cover only materials having normal or average gradation characteristics. Procedures covered in this specification are not intended for evaluating the performance nutrients associated with vegetative (green) roof growing media. Where other materials are to be used, appropriate limits suitable to their use must be specified.  
1.2 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 nonconformance with the standard.  
1.3 This standard offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process.  
1.4 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 determine the applicability of regulatory limitations prior to use.  
1.5 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.

General Information

• Status: Published
• Publication Date: 31-Dec-2023
• ICS: 65.020.20 - Plant growing
• ICS: 91.060.20 - Roofs
• Technical Committee: D08 - Roofing and Waterproofing
• Drafting Committee: D08.24 - Sustainability

Relations

• Replaces: ASTM E2788/E2788M-18 - Standard Specification for Use of Expanded Shale, Clay and Slate (ESCS) as a Mineral Component in the Growing Media and the Drainage Layer for Vegetative (Green) Roof Systems
• Effective Date: 01-Jan-2024
• Refers: ASTM C88/C88M-24 - Standard Test Method for Soundness of Aggregates by Use of Sodium Sulfate or Magnesium Sulfate
• Effective Date: 01-Jan-2024
• Refers: ASTM C88/C88M-18 - Standard Test Method for Soundness of Aggregates by Use of Sodium Sulfate or Magnesium Sulfate
• Effective Date: 01-Aug-2018
• Referred By: ASTM E2777-20 - Standard Guide for Vegetative (Green) Roof Systems
• Effective Date: 01-Jan-2024
• Referred By: ASTM E2400/E2400M-19 - Standard Guide for Selection, Installation, and Maintenance of Plants for Vegetative (Green) Roof Systems
• Effective Date: 01-Jan-2024

Overview

ASTM E2788/E2788M-24 is the internationally recognized standard specification for the quality and grading of expanded shale, clay, and slate (ESCS) when used as a mineral component in the growing media and the drainage layer for vegetative (green) roof systems. Issued by ASTM International, this standard defines the physical and chemical requirements, testing methods, and terminology relevant to ESCS in both intensive and extensive green roof applications. The specification ensures suitable material characteristics to support plant growth, manage water, and provide effective drainage-crucial for sustainable green roof performance.

Expanding urban interest in vegetative roofs has amplified the demand for defined materials like ESCS, known for being lightweight, highly porous, and providing robust drainage and aeration. ASTM E2788/E2788M-24 guides material selection for architects, engineers, contractors, and construction product manufacturers focused on green infrastructure and sustainability.

Key Topics

• Material Scope and Definition
  ESCS is a lightweight, ceramic aggregate made by expanding and vitrifying select shale, clay, or slate in a rotary kiln. The standard applies to ESCS used both as a drainage layer and as a mineral amendment in green roof growing media.

• Gradation and Quality Requirements
  The standard specifies strict gradation limits to ensure adequate porosity, water retention, and load-bearing capacity-vital properties for green roof systems.

• Physical Properties
  Key parameters covered include:

  • Bulk density
  • Air-filled porosity
  • Water holding capacity
  • Permeability
  • Frost and abrasion resistance

• Chemical Properties
  Limits for pH and salt content are outlined to ensure plant health and compatibility with associated materials.

• Differentiation of Applications
  Requirements are tailored for both intensive (deeper media, wider plant selection) and extensive (shallow, low-maintenance plantings) green roof systems.

• Referenced Test Methods
  The document refers to established ASTM test methods and guides for determining physical and chemical properties and for sampling and analysis, ensuring consistency and reliability.

• Terminology for Clarity
  Consistent definitions are provided for key terms such as extensive/intensive green roof systems, growing media, and ESCS aggregate.

Applications

ASTM E2788/E2788M-24 is specifically designed for use in:

• Green Roof Installations

  • Selection and grading of ESCS for extensive and intensive vegetative (green) roofs.
  • Ensuring materials meet structural and horticultural performance criteria.

• Landscape Architecture and Urban Design

  • Specification of lightweight aggregates for projects where weight, drainage, and sustainability are priorities.

• Construction and Engineering

  • Contractors and product manufacturers use this standard to source ESCS that complies with best practices for water management, plant health, and structural integration.

• Sustainable Infrastructure

  • Supports green building certification and urban sustainability initiatives through the use of environmentally responsible material solutions.

Related Standards

Several referenced and related ASTM standards support testing, use, and terminology for ESCS and vegetative roof systems:

• ASTM C29/C29M - Test Method for Bulk Density and Voids in Aggregate
• ASTM C88/C88M - Test Method for Soundness of Aggregates by Use of Sodium or Magnesium Sulfate
• ASTM C136/C136M - Test Method for Sieve Analysis of Aggregates
• ASTM E2777 - Guide for Vegetative (Green) Roof Systems
• ASTM E2399/E2399M - Test Method for Maximum Media Density for Dead Load Analysis of Green Roofs
• ASTM E2400/E2400M - Guide for the Selection, Installation, and Maintenance of Plants on Green Roofs

Conclusion

Adhering to ASTM E2788/E2788M-24 enables the consistent specification and use of ESCS as a high-performance aggregate for green roof systems, supporting plant establishment, stormwater management, and roofing longevity. Its implementation helps stakeholders achieve reliable outcomes in sustainable building and landscape projects, aligning with international best practices for quality and environmental stewardship.

Standards Content (Sample)

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.
Designation: E2788/E2788M − 24
Standard Specification for
Use of Expanded Shale, Clay, and Slate (ESCS) as a Mineral
Component in the Growing Media and the Drainage Layer
for Vegetative (Green) Roof Systems
This standard is issued under the fixed designation E2788/E2788M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 This specification covers the quality and grading of the
ization established in the Decision on Principles for the
following materials for use as a mineral component of growing
Development of International Standards, Guides and Recom-
media and drainage layer for extensive and intensive vegetative
mendations issued by the World Trade Organization Technical
(green) roof systems. The requirements are intended to cover
Barriers to Trade (TBT) Committee.
only materials having normal or average gradation character-
istics. Procedures covered in this specification are not intended
2. Referenced Documents
for evaluating the performance nutrients associated with veg-
2.1 ASTM Standards:
etative (green) roof growing media. Where other materials are
C29/C29M Test Method for Bulk Density (“Unit Weight”)
to be used, appropriate limits suitable to their use must be
and Voids in Aggregate
specified.
C88/C88M Test Method for Soundness of Aggregates by
1.2 The values stated in either SI units or inch-pound units
Use of Sodium Sulfate or Magnesium Sulfate
are to be regarded separately as standard. The values stated in
C127 Test Method for Relative Density (Specific Gravity)
each system may not be exact equivalents; therefore, each 3
and Absorption of Coarse Aggregate (Withdrawn 2024)
system shall be used independently of the other. Combining
C136/C136M Test Method for Sieve Analysis of Fine and
values from the two systems may result in nonconformance
Coarse Aggregates
with the standard.
C330/C330M Specification for Lightweight Aggregates for
1.3 This standard offers an organized collection of informa-
Structural Concrete
tion or a series of options and does not recommend a specific
C331/C331M Specification for Lightweight Aggregates for
course of action. This document cannot replace education or
Concrete Masonry Units
experience and should be used in conjunction with professional
D75/D75M Practice for Sampling Aggregates
judgment. Not all aspects of this guide may be applicable in all
D3080/D3080M Test Method for Direct Shear Test of Soils
circumstances. This ASTM standard is not intended to repre-
Under Consolidated Drained Conditions
sent or replace the standard of care by which the adequacy of D5883 Guide for Use of Rotary Kiln Produced Expanded
a given professional service must be judged, nor should this
Shale, Clay or Slate (ESCS) as a Mineral Amendment in
document be applied without consideration of a project’s many Topsoil Used for Landscaping and Related Purposes
unique aspects. The word “Standard” in the title of this
E2114 Terminology for Sustainability
document means only that the document has been approved E2397/E2397M Practice for Determination of Dead Loads
through the ASTM consensus process.
and Live Loads Associated with Vegetative (Green) Roof
Systems
1.4 This standard does not purport to address all of the
E2399/E2399M Test Method for Maximum Media Density
safety concerns, if any, associated with its use. It is the
for Dead Load Analysis of Vegetative (Green) Roof
responsibility of the user of this standard to establish appro-
Systems
priate safety, health, and environmental practices and deter-
E2777 Guide for Vegetative (Green) Roof Systems
mine the applicability of regulatory limitations prior to use.
1 2
This specification is under the jurisdiction of ASTM Committee D08 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Roofing and Waterproofing and is the direct responsibility of Subcommittee D08.24 contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
on Sustainability. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Jan. 1, 2024. Published January 2024. Originally the ASTM website.
approved in 2011. Last previous edition approved in 2018 as E2788/E2788M – 18. The last approved version of this historical standard is referenced on
DOI: 10.1520/E2788_E2788M-24. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2788/E2788M − 24
G51 Test Method for Measuring pH of Soil for Use in kiln. It is a highly porous and low-density material. The raw
Corrosion Evaluations shale, clay, or slate used to produce ESCS is fired in the kiln at
temperatures exceeding 1000 °C. As it exits the kiln, the
3. Terminology
material is sterile, inert, and ceramic. Some crushing may be
3.1 Definitions:
performed to facilitate final screening in a screening system.
3.1.1 For terms related to expanded shale, clay, and slate
ESCS is generally neutral in pH, although the pH can vary
(ESCS), refer to Guide D5883.
somewhat depending on the raw material and the fuel used for
3.1.2 For terms related to sustainability relative to the
processing. Test Method C29/C29M determines density (loose
performance of buildings, refer to Terminology E2114.
unit weight). Test Method C127 is used to determine the
3.2 Definitions of Terms Specific to This Standard:
absorption after soaking the material. The particle distribution
3.2.1 expanded shale, clay, and slate (ESCS), n—a
is determined with the appropriate sieves as stated in Test
lightweight, ceramic material produced by expanding and
Method C136/C136M. The ESCS is to be sampled in accor-
vitrifying select shale, clay, or slate in a rotary kiln.
dance with Practice D75/D75M.
3.2.2 extensive vegetative (green) roof system, n—a vegeta-
tive (green) roof system that utilizes a narrow range of species 5. Requirements
limited to herbs, grasses, mosses, and drought-tolerant succu-
5.1 The aggregates shall conform to the gradation require-
lents such as Sedum. These types of plants can potentially be
ments specified in Tables 1 and 2. For the drainage layer, no
sustained in a shallow growing media layer, usually six inches
more than 2 % by volume of aggregate particles shall have a
and under, with generally less maintenance than intensive
diameter of <0.075 mm (No. 200 screen). As a component in
vegetative (green) roof systems.
the total growing media, the aggregate shall not contribute to
3.2.3 vegetative (green) r
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E2788/E2788M − 18 E2788/E2788M − 24
Standard Specification for
Use of Expanded Shale, Clay, and Slate (ESCS) as a Mineral
Component in the Growing Media and the Drainage Layer
for Vegetative (Green) Roof Systems
This standard is issued under the fixed designation E2788/E2788M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This specification covers the quality and grading of the following materials for use as a mineral component of growing media
and drainage layer for extensive and intensive vegetative (green) roof systems. The requirements are intended to cover only
materials having normal or average gradation characteristics. Procedures covered in this specification are not intended for
evaluating the performance nutrients associated with vegetative (green) roof growing media. Where other materials are to be used,
appropriate limits suitable to their use must be specified.
1.2 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-conformancenonconformance with the standard.
1.3 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 determine the applicability of
regulatory limitations prior to use.
1.3 This standard offers an organized collection of information or a series of options and does not recommend a specific course
of action. This document cannot replace education or experience and should be used in conjunction with professional judgment.
Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace
the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied
without consideration of a project’s many unique aspects. The word "Standard"“Standard” in the title of this document means only
that the document has been approved through the ASTM consensus process.
1.4 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 determine the applicability of
regulatory limitations prior to use.
1.5 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.
This specification is under the jurisdiction of ASTM Committee D08 on Roofing and Waterproofing and is the direct responsibility of Subcommittee D08.24 on
Sustainability.
Current edition approved March 1, 2018Jan. 1, 2024. Published March 2018January 2024. Originally approved in 2011. Last previous edition approved in 20112018 as
E2788 – 11.E2788/E2788M – 18. DOI: 10.1520/E2788_E2788M-18.10.1520/E2788_E2788M-24.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2788/E2788M − 24
2. Referenced Documents
2.1 ASTM Standards:
C29/C29M Test Method for Bulk Density (“Unit Weight”) and Voids in Aggregate
C88C88/C88M Test Method for Soundness of Aggregates by Use of Sodium Sulfate or Magnesium Sulfate
C127 Test Method for Relative Density (Specific Gravity) and Absorption of Coarse Aggregate (Withdrawn 2024)
C136/C136M Test Method for Sieve Analysis of Fine and Coarse Aggregates
C330/C330M Specification for Lightweight Aggregates for Structural Concrete
C331/C331M Specification for Lightweight Aggregates for Concrete Masonry Units
D75/D75M Practice for Sampling Aggregates
D3080D3080/D3080M Test Method for Direct Shear Test of Soils Under Consolidated Drained Conditions
D5883 Guide for Use of Rotary Kiln Produced Expanded Shale, Clay or Slate (ESCS) as a Mineral Amendment in Topsoil Used
for Landscaping and Related Purposes
E2114 Terminology for Sustainability
E2396/E2396ME2397/E2397M Test Method for Saturated Water Permeability of Granular Drainage Media [Falling-Head
Method] for Practice for Determination of Dead Loads and Live Loads Associated with Vegetative (Green) Roof Systems
E2399/E2399M Test Method for Maximum Media Density for Dead Load Analysis of Vegetative (Green) Roof Systems
E2400/E2400M Guide for Selection, Installation, and Maintenance of Plants for Vegetative (Green) Roof Systems
E2777 Guide for Vegetative (Green) Roof Systems
G51 Test Method for Measuring pH of Soil for Use in Corrosion Evaluations
3. Terminology
3.1 Definitions:
3.1.1 For terms related to Expanded Shale, Clay and Slateexpanded shale, clay, and slate (ESCS), refer to TerminologyGuide
D5883.
3.1.2 For terms related to sustainability relative to the performance of buildings, refer to Terminology E2114.
3.2 Definitions of Terms Specific to This Standard:
3.2 Definitions of Terms Specific to This Standard:
3.2.1 expanded shale, clay, and slate (ESCS), n—a lightweight, ceramic material produced by expanding and vitrifying select
shale, clay, or slate in a rotary kiln.
3.2.2 extensive vegetative (green) roof system, n—a vegetative (green) roof system that utilizes a narrow range of species limited
to herbs, grasses, mosses, and drought-tolerant succulents such as Sedum. These types of plants can potentially be sustained in a
shallow growing media layer, usually six inches and under, with generally less maintenance than intensive vegetative (green) roof
systems.
3.2.3 vegetative (green) roof system, n—assembly designed to support vegetation growth above a waterproofed membrane.
3.2.4 growing media (media), n—the substrate in which plants take hold and develop.
3.2.5 intensive vegetative (green) roof system, n—a vegetative (green) roof system that utilizes a wide variety of plant species that
require a growing media greater than six inches that may include lawns, trees, and shrubs.
3.2.6 Sedums, n—a succulent plant known for its tolerance for extreme conditions.
3.3 expanded shale, clay, and slate (ESCS), n—a lightweight, ceramic material produced by expanding and vitrifying select shale,
clay, or slate in a rotary kiln.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
E2788/E2788M − 24
3.4 extensive vegetative (green) roof system, n—a vegetative (green) roof system that utilizes a narrow range of species limited
to herbs, grasses, mosses, and drought tolerant succulents such as Sedum. These types of plants can potentially be sustained in a
shallow growing media layer usually six inches and under with generally less maintenance than intensive vegetative (green) roof
systems.
3.5 vegetative (green) roof system, n—assembly designed to support vegetation growth above a waterproofed membrane.
3.6 growing media (media), n—the substrate in which plants take hold and develop.
3.7 intensive vegetative (green) roof system, n—a vegetative (green) roof system that utilizes a wide variety of plant species that
require a growing media greater than six inches that may include lawns, trees, and shrubs.
3.8 Sedums, n—a succulent plant known for its tolerance for extreme conditions.
4. Materials and Manufacture
4.1 ESCS is a lightweight, ceramic material produced by expanding and vitrifying select shale, clay, or slate in a rotary kiln. It
is a highly porous and low-density material. The raw shale, clay, or slate used to produce ESCS is fired in the kiln at temperatures
exceeding 1000°C.1000 °C. As it exits the kiln, the material is sterile, inert, and ceramic. Some crushing may be performed to
facilitate final screening in a screening system. ESCS is generally neutral in pH, although the pH can vary somewhat depending
on the raw material and the fuel used for processing. Test Method C29/C29M determines density (loose unit weight). Test Method
C127 is used to determine the absorption after soaking the material. The particle distribution is determined with the appropriate
sieves as stated in Test Method C136/C136M. The ESCS is to be sampled in accordance with Practice D75/D75M.
5. Requirements
5.1 The aggregates shall conform to the gradation
...