By Bob Mackey
Geo terminology—The current issue
The ASTM Committee D35 on Geosynthetics was established to develop standards on test methods, guides, practices, and specifications for geosynthetic materials. A component critical to the development of these standards is an agreement within the committee on the geosynthetic terminology used throughout the standards and definitions for each term. As with all things, the committee’s understanding of geosynthetic materials and how to define them is an ongoing process. Because of growth in these materials and their applications, geosynthetic terminology requires diligent and ongoing re-evaluation. This is particularly true when new geosynthetics products enter the marketplace that challenge the committee’s previous understanding of a term for that product. Such is the current situation for the ASTM D35.93 Subcommittee on Terminology, led by that subcommittee’s chairman, Robert Lozano.
There are new geosynthetic products entering the marketplace for which the manufacturers seek to classify their products as geomembranes. These products challenge the current ASTM definition of a geomembrane. ASTM D4439 “Standard Terminology for Geosynthetics” currently defines a geomembrane as “an essentially impermeable geosynthetic composed of one or more synthetic sheets.” For example, D35 committee members must consider if any of the following products are geomembranes:
- laminate or coated geotextile
- polymer infused geotextile
- concrete infused geotextile or concrete sandwiched between two geotextiles
Each of the above may function as a geomembrane, yet fail to meet the current ASTM definition. Revising the current geomembrane definition to include these products would result in ASTM standards that would no longer be applicable for testing a wide range of geomembrane material. Although ASTM D35’s primary responsibility is to develop good applicable standards for geosynthetic materials, the committee is aware that numerous geosynthetic terms and their definitions have significant applications beyond the responsibility of ASTM. A revision of the geomembrane definition to include these products would conflict with the present understanding of a geomembrane product for those within and outside the geosynthetic field. However, the manufacturers of these new products want their product(s) classified as a “geomembrane.” To better understand why they seek this classification, an understanding of geosynthetic history is helpful.
Geo terminology history
Since its inception, the geosynthetic industry has experienced a remarkable growth in the breadth of products and the depth of technical knowledge of manufactured geosynthetic materials.
“Geo terminology” first came into existence when an extremely wise man (aka, Dr. J.P. Giroud) developed the term geomembrane to describe a polymeric sheet used for the bottom liner of a landfill. The importance of the geomembrane’s integration into landfill construction, thereby safeguarding the environment, cannot be understated.
Design engineers, regulators, and landfill operators quickly accepted this new term. Soon after, everyone involved in the “geosynthetic” industry was marketing “geo” this and “geo” that. A textile was no longer just a textile, it was a “geotextile.” These new products included geonets, geogrids, geocells, geofoams, various geocomposites, and geosynthetic clay liners. This author remembers thinking that this “geo” terminology had gone too far when a particular polymer pipe was no longer being marketed as a “pipe,” it was now a “geopipe.” Unlike other geosynthetic terms, the term geopipe did not find wide acceptance within the geosynthetic community.
Manufacturers named their new synthetic products based on their geometry, previous or current functions, compositions, etc. The inclusion of the “geo” within the material’s name assisted the manufacturer’s ability to have its product accepted, and purchased, within the geosynthetic field.
Over the years, the D35 committee has seen numerous occasions where manufacturers have approached the committee for assistance to develop ASTM standards for their products that included the development of new or revised “geo terminology.” Having an ASTM standard provides the manufacturer with a degree of credibility for its geosynthetic product.
Historically, the D35 committee has attempted to follow the geosynthetic terminology concepts first presented in the International Geosynthetic Society document “Recommended Descriptions of Geosynthetic Functions, Geosynthetic Terminology, Mathematical and Graphical Symbols.” The D35 committee needed to change the IGS geosynthetic terminology to meet the ongoing demands to update and revise ASTM standards according to the most current geosynthetic knowledge.
Geo conflicts between marketing and terminology
The ASTM D35 committee recognizes that manufacturers may use the establishment of ASTM standards to build credibility for their products. The problem arises when a manufacturer seeks a particular classification for its product.
For example, a manufacturer may want its product classified as a “geomembrane,” which will allow this product to be considered within a desirable marketplace. The D35 committee must consider only if the product is in accordance with the current definition of a geomembrane, as specified in ASTM 4439. If the product does not meet the definition of a geomembrane, it cannot be classified as a geomembrane within ASTM.
Manufacturers strive to either obtain specific material classifications or seek to revise the current definition to include their products. Other manufacturers of similar products may strive to limit the definition of a term or classification to minimize competition. This conflict is intensified when a geosynthetic term is used within regulations and laws.
This conflict is best reflected in the work performed by the International Standards Organization’s (ISO) Technical Committee 221 on Geosynthetics (TC221). TC221 worked for many years to develop uniform geosynthetic terminology. A conflict arose over the term geomembrane. One or more nations considered the classification of geomembranes to include geosynthetic clay liners (GCLs). By not classifying a GCL as a geomembrane, one nation may not be able to market the product produced by one of its native manufacturers to other nations. However, most of the member nations do not classify a GCL as a geomembrane and would not accept the inclusion of GCL within the definition of a geomembrane. To resolve this classification, terminology, and definition issue, TC221 developed new terminology where all geosynthetic products that function as “barriers” are classified as “geosynthetic barriers.” There are subclassifications to the geosynthetic barrier term, such as:
- polymeric geosynthetic barrier.
- clay geosynthetic barrier.
- bituminous geosynthetic barrier.
Although the above solution helped resolve a classification and terminology issue, acceptance by the international geosynthetic community has been slow. At least one nation has the term geomembrane written into its laws, thereby making it almost impossible to implement this new terminology. The ISO terminology can be found within ISO Standard 10318, “Geosynthetics—Terms and Definitions.”
Geo problems with ASTM terminology—geomembranes
The term geomembrane has extended well beyond the confines of ASTM standards and is deeply embedded within the language outside the geosynthetic field. It has become almost synonymous with (excuse the phrase) a “plastic sheet” or “liner.”
Although there are several new geosynthetic products that could perform the same function as a geomembrane, the D35 committee believes the users of ASTM standards would find it hard to accept these new products as “geomembranes” or within the traditional understanding of “What is a geomembrane?”.
As new geosynthetic materials are brought into the marketplace, the D35 committee must also consider the ability to adapt or revise various geosynthetic terminologies as it may apply to these new products. In this regard, the traditional term geomembrane and its definition is too well established to allow ongoing revisions.
Geo solution—ISO #10318 terminology
The solution to the geomembrane terminology issue can be found within ISO 10318, “Geosynthetics—Terms and Definitions.”
Defining various geosynthetic products under their function and subcategorizing the products according to their compositions will afford the D35 committee (and the ISO TC221 Committee) the ability to develop appropriate terminology and definitions for each category/subcategory. There is flexibility is this methodology for the development of applicable terminology and subsequent definitions. Using ISO terminology could generate valuable harmonization between the ASTM geosynthetic standards and ISO standards, and could facilitate common terminology usage throughout the global geosynthetic field.
The ASTM D35 committee understands that its decision to start integrating ISO terminology into ASTM standards could have a profound impact on the geosynthetic field. The committee also realizes the work to perform this terminology conversion within ASTM standards is enormous. How to proceed with this task has not yet been determined. Various conflicts will arise through this conversion process and must be resolved by all interested parties. We hope that there will not be any insurmountable issues for the D35.93 Subcommittee on Terminology. The D35 committee is sure of only two things:
- This terminology conversion process must be performed.
- Robust communication between ASTM and interested parties is the key to successfully accomplishing this objective.
The development of ASTM standard test methods requires “geo terminology” to be defined with agreed-upon definitions by members of the ASTM Committee D35 on Geosynthetics.
Although D35’s primary responsibility is to develop good applicable standards for geosynthetic materials, the committee is aware that numerous geosynthetic terms and their definitions have significant use beyond ASTM. The term geomembrane is the best example of how some geo terminology has found acceptance outside the geosynthetic field and its usage is so engrained that revising its definition is almost impossible.
The D35 committee believes the methodology of the terms within ISO Standard 10318, “Geosynthetics—Terms and Definitions,” may allow for more flexibility for the future development of appropriate terminology within ASTM standards. Conversion of ASTM geosynthetic standards to the ISO 10318 terminology will also bring about greater harmonization of standards and terminology throughout the global geosynthetic field.
Request for geo assistance
The ASTM Committee D35 on Geosynthetics will start the process of converting D35 geosynthetic standards to ISO terminology at its Jan. 29–31, 2014, meetings in Houston, Texas.
This process will start with the revision of standards that have the term geomembrane within them. The procedure for this conversion so far has not been determined and will be discussed further within the D35.93 terminology sub-committee meeting, Friday, Jan. 31, 8–9 a.m.
The D35 committee seeks input and assistance from interested parties on how to proceed with this conversion process. For more information about the January 2014 ASTM meeting or other geosynthetic terminology conversion issues, please contact:
- Robert Lozano, chairman, ASTM D35.93 Subcommittee on Terminology.
- Katerina Koperna, ASTM D35 staff manager.
- Bob Mackey, chairman, ASTM Committee D35 on Geosynthetics.
Bob Mackey, principal engineer for S2L Inc., Maitland, Fla., is the chairman of the ASTM D35 Committee on Geosynthetics. He is also the current president of the North American Geosynthetics Society (NAGS) and he is a member of Geosynthetics magazine’s Editorial Advisory Committee.
ASTM D4439, “Standard Terminology for Geosynthetics”
IGS document, “Recommended Descriptions of Geosynthetics Functions, Geosynthetics Terminology, Mathematical and Graphical Symbols.”
ISO Standard 10318, “Geosynthetics—Terms and Definitions”