Design using geosynthetics — Part 9: Barriers

This document considers the guidance for geotechnical and civil engineers involved in the design of the barrier function.

Design pour géosynthétiques — Partie 9: Barrières

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TECHNICAL ISO/TR
REPORT 18228-9
First edition
2022-04
Design using geosynthetics —
Part 9:
Barriers
Design pour géosynthétiques —
Partie 9: Barrières
Reference number
ISO/TR 18228-9:2022(E)
© ISO 2022
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ISO/TR 18228-9:2022(E)
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© ISO 2022

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ISO/TR 18228-9:2022(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction .............................................................................................................................................................................................................................. vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................................................................... 1

4 Pictograms ................................................................................................................................................................................................................. 2

4.1 Product and function ........................................................................................................................................................................ 2

4.2 Applications............................................................................................................................................................................................... 2

4.2.1 Containment application, non-landfill (CA) ................................................................................................ 2

4.2.2 Chemical containment, non-landfill (CC) ................................... ................................................................... 2

4.2.3 Construction waterproofing (CW) ..................................................................................................................... 3

4.2.4 Landfill base lining (LBL) ........................................................................................................................................... 3

4.2.5 Landfills caps (LC) ............................................................................................................................................................ 3

4.2.6 Secondary containment (SC) ................................................................................................................................... 4

4.2.7 Transport infrastructure applications (TIA) ............................................................................................ 4

4.2.8 Tunnels (Tu) ............................................................................................................................................................................ 5

4.2.9 Water retaining structure (WRS-e), e.g. balancing ponds, dams, dykes and

canals (usually empty) .................................................................................................................................................. 5

4.2.10 Water retaining structure (WRS-f), e.g. reservoirs, canals (usually full) ...................... 5

5 Design Criteria ....................................................................................................................................................................................................... 6

6 Materials ....................................................................................................................................................................................................................... 7

6.1 General ........................................................................................................................................................................................................... 7

6.2 HDPE ................................................................................................................................................................................................................ 7

6.3 LLDPE.............................................................................................................................................................................................................. 7

6.4 fPP ...................................................................................................................................................................................................................... 7

6.5 PVC .................................................................................................................................................................................................................... 7

6.6 EPDM ............................................................................................................................................................................................................... 7

6.7 Bitumen ......................................................................................................................................................................................................... 7

6.8 EIA (ethylene interpolymer alloy) ......................................................................................................................................... 7

6.9 Bentonite ......... ............................................................. ................................................................................................................................ 7

6.10 Sodium bentonite ................................................................................................................................................................................. 8

6.11 Calcium bentonite ................................................................................................................................................................................ 8

7 Properties relevant to design ................................................................................................................................................................8

7.1 General ........................................................................................................................................................................................................... 8

7.2 Chemical resistance ........................................................................................................................................................................... 9

7.3 Physical properties ............................................................................................................................................................................. 9

7.4 Durability/weathering ................................................................................................................................................................. 10

7.4.1 General ..................................................................................................................................................................................... 10

7.4.2 Mechanisms of degradation of the GBR ...................................................................................................... 10

7.4.3 Mechanisms of degradation of the joints ................................................................................................... 10

8 Principles of design ........................................................................................................................................................................................11

8.1 General ........................................................................................................................................................................................................ 11

8.2 Subgrade preparation ................................................................................................................................................................... 11

8.3 Slope stability ....................................................................................................................................................................................... 11

8.4 Climate conditions............................................................................................................................................................................12

8.5 Temperature effects (thermal expansion and stiffness) ................................................................................12

8.6 Protection and testing .................................................................................................................................................................. 12

8.6.1 Puncture protection .....................................................................................................................................................12

8.6.2 Installation issues, excluding jointing ..........................................................................................................12

8.6.3 QC on site ................................................................................................................................................................................13

8.6.4 Hydraulic uplift ................................................................................................................................................................. 14

iii
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ISO/TR 18228-9:2022(E)

9 Example design chart ..................................................................................................................................................................................14

Bibliography .............................................................................................................................................................................................................................16

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ISO/TR 18228-9:2022(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see

www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 221, Geosynthetics.
A list of all parts in the ISO 18228 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www.iso.org/members.html.
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ISO/TR 18228-9:2022(E)
Introduction

The ISO 18228 series provides guidance for designs using geosynthetics for soils and below ground

structures in contact with natural soils, fills and asphalt. The series contains 10 parts which cover

designs using geosynthetics, including guidance for characterization of the materials to be used and

other factors affecting the design and performance of the systems which are particular to each part,

with ISO/TR 18228-1 providing general guidance relevant to the subsequent parts of the series.

The series is generally written in a limit state format and guidelines are provided in terms of partial

material factors and load factors for various applications and design lives, where appropriate.

For each of the design considerations, the characteristics of the geosynthetics and the test methods

normally used to quantify the properties of the geosynthetics are described. Some regional specific

rules and regulations that normally apply to designs using geosynthetics in these regions are also

mentioned.

This document contains recommendations and guidance for the design of geosynthetic barriers in

geotechnical applications. The standard provides design guidance over various applications, design

lives, material types, parameters and site-specific conditions. Professional judgement is needed in all

designs. Be aware that national regulations might apply. This document is intended to assist in the

process, by identifying parameters which are relevant.

Design using geosynthetic barriers (GBRs) takes into account the nature of the material in contact

with the GBR, both underneath (the substrate), alongside and on top (the contained substances). As the

primary function of a GBR is to retain or exclude fluids, primary issues in design relate to its ability to

perform this function. Often, but not always, GBR materials are incorporated into structures with an

extensive life expectancy and therefore the material's durability (its ability to continue to perform its

primary function over time) is critical.

Balancing the combination of often conflicting performance criteria and different GBR materials

to the proposed installation is always a complex matter. This inevitably comes down to professional

judgement. This document does not set out to and cannot solve this potential conflict but seeks to assist

the designer in identifying and clarifying the various components of the decision-making process by

identifying existing standards for comparisons of individual parameters and giving some direction on

prioritization in various applications as well as conflicting performance characteristics which may be

encountered.
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TECHNICAL REPORT ISO/TR 18228-9:2022(E)
Design using geosynthetics —
Part 9:
Barriers
1 Scope

This document considers the guidance for geotechnical and civil engineers involved in the design of the

barrier function.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 10318-1, Geosynthetics — Part 1: Terms and definitions
3 Terms and definitions

For the purposes of this document, the terms and definitions in ISO 10318-1:2015 and the following

apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
barrier
use of a geosynthetic to prevent or limit the migration of fluids
3.2
geosynthetic barrier
GBR

low-permeability geosynthetic material, used in geotechnical and civil engineering applications with

the purpose of reducing or preventing the flow of fluid through the construction
3.3
geomembrane
GBR-P
polymeric geosynthetic barrier

factory-assembled structure of geosynthetic materials in the form of a sheet in which the barrier (3.1)

function is essentially fulfilled by polymers
3.4
clay geosynthetic barrier
GBR-C
geosynthetic clay liner

factory-assembled structure of geosynthetic materials in the form of a sheet in which the barrier (3.1)

function is essentially fulfilled by clay
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ISO/TR 18228-9:2022(E)
3.5
bituminous geomembrane
bituminous geosynthetic barrier
GBR-B

factory-assembled structure of geosynthetic materials in the form of a sheet in which the barrier (3.1)

function is essentially fulfilled by bitumen
4 Pictograms
4.1 Product and function

Graphical symbols and pictograms for geosynthetic barriers can be found in ISO 10318-2:2015.

4.2 Applications
4.2.1 Containment application, non-landfill (CA)

GBRs are used to inhibit the ingress of water and the uncontrolled escape of fluids in or out of the

construction (see Figure 1). The minimum confining stress is typically of the order of 20 kN/m .

Figure 1 — Containment application, non-landfill (CA)
4.2.2 Chemical containment, non-landfill (CC)

The function of the GBR in this application is to contain any hazardous liquids or constituents within a

construction. The typical confining stress is in the range of less than 50 kN/m , whereas the hydraulic

gradient i is typically less than 500. See Figure 2.
Figure 2 — Chemical containment, non-landfill (CC)
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ISO/TR 18228-9:2022(E)
4.2.3 Construction waterproofing (CW)

The function of the GBR in this application is to inhibit the passage of water into the underground

structures (other than tunnels and associated structures). The typical confining stress is less than

100 kN/m and the gradient can be up to 400, however both can be much higher. See Figure 3.

Figure 3 — Construction waterproofing (CW)
4.2.4 Landfill base lining (LBL)

GBRs are used to inhibit the ingress of groundwater and the uncontrolled escape of landfill leachate

and/or gases in the construction of solid waste storage and disposal sites as base liners. The typical

2 2

confining stress is in the range of 50 kN/m to 1 000 kN/m , whereas the hydraulic gradient i is typically

less than 50. See Figure 4.
Figure 4 — Landfill base lining (LBL)
4.2.5 Landfills caps (LC)

GBRs are used to inhibit the ingress of water and the uncontrolled escape of fluids and/or gases in the

construction of solid or industrial waste facilities. The typical confining stress is in the range of 10 kN/

2 2
m to 50 kN/m . See Figure 5.
Figure 5 — Landfills caps (LC)
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ISO/TR 18228-9:2022(E)
4.2.6 Secondary containment (SC)

The function of the GBR in this application is to contain any hazardous liquids or constituents resulting

from storage silos or similar containment failures. The typical confining stress is in the range of less

than 25 kN/m , whereas the hydraulic gradient i is typically less than 150. See Figure 6.

Figure 6 — Secondary containment (SC)
4.2.7 Transport infrastructure applications (TIA)

The function of the GBR in these applications is to inhibit any hazardous liquids or constituents

resulting from vehicle, railway or airline traffic entering the sensitive location, mainly in infrastructure

applications, such as roads, railways and airports. The typical confining stress is in the range of less

than 50 kN/m , whereas the hydraulic gradient i is typically less than 50. See Figure 7.

Figure 7 — Transport instrastructure application (TIA)
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ISO/TR 18228-9:2022(E)
4.2.8 Tunnels (Tu)

The function of the GBR in this application is to inhibit the passage of water into the construction

of tunnels and associated underground structures. The typical confining stress in a cut and cover

application is in the range of less than 100 kN/m and a gradient up to 400. In bored applications the

confining stresses and gradients are typically much higher. See Figure 8.
Figure 8 — Tunnels

4.2.9 Water retaining structure (WRS-e), e.g. balancing ponds, dams, dykes and canals (usually

empty)

In applications with a temporary water level such as balancing ponds, dams, dykes and canals, GBRs

are mostly used as the sole hydraulic barrier or in combination with an existing soil barrier. The

function of the GBR is to reduce seepage through the system thereby reducing water loss and providing

environmental protection. The typical confining stress is less than 50 kN/m , whereas the hydraulic

gradient is typically higher than 100 and can reach many hundreds. See Figure 9.
Figure 9 — Water retaining structure (WRS-e)
4.2.10 Water retaining structure (WRS-f), e.g. reservoirs, canals (usually full)

In applications where a constant water level is maintained such as canals, rivers and surface

impoundments, GBRs are mostly used as the sole hydraulic barrier or in combination with an existing

soil barrier (such as a clay core within a dam structure). The function of the GBR is to reduce seepage

through the system thereby reducing water loss from the waterway or storage impoundment.

Additionally, it is used to prevent the weakening of the internal structure of the dam. The typical

confining stress is less than 50 kN/m , whereas the hydraulic gradient i is typically higher than 100 and

can reach many hundreds. See Figure 10.
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ISO/TR 18228-9:2022(E)
Figure 10 — Water retaining structure (WRS-f)
5 Design Criteria

This Clause presents key design criteria that could be addressed for proper hydraulic and mechanical

performance of a GBR. There are other issues as well. In general, the designer could go beyond this

document into the idiosyncrasies of the product-specific and site-specific considerations. GBRs in

this document are products to limit the movement of fluids and/or gases. Table 1 suggests various

applications, with ratings from 1 (important) to 4 (not relevant), and selected criteria that might be

applicable for design consideration. In all cases, product-specific and site-specific conditions can

prevail.

Table 1 — Subjective ratings for importance of various criteria of common GBR applications

Characteristic CA CC CW LBL LC SC TIA TU WRS-e WRS-f
parameter
Chemical resistance 2 1 3 1 2 1 1 2 3 3
Physical proper-
ties
Hydraulic resist- permeability 1 1 1 1 1 1 1 1 1 1
ance
Mechanical prop- tensile, puncture, 1 1 2 1 1 2 1 1 1 1
erty tear strength
uni- and multi-axial 2 2 3 3 2 2 2 3 2 2
elongation
Abrasion resistance 4 4 4 4 4 4 4 4 2 2
Durability 50 25 50 100 50 25 25 100 25 25
yrs yrs yrs yrs yrs yrs yrs yrs yrs yrs
Installation 1 1 1 1 1 1 1 1 1 1
Key
1: Important
2: Project-dependent requirement
3: Rarely required
4: Not relevant

Vertical barriers are sometimes used within a support fluid, (i.e. bentonite, cement-bentonite or

mixed in place material) in an excavated trench. The support fluid needs to be of such density that

the trench remains open. It is also recommended to review the site investigation data for any possible

obstructions during installation or integrity of the system (i.e. boulders, roots or other debris) and

contact a specialized designer or contractor. The system needs to terminate in an impermeable stratum

to ensure water tightness.
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ISO/TR 18228-9:2022(E)
6 Materials
6.1 General

GBRs are manufactured from various compounds offering different performance criteria. 6.2 to 6.11

describe those most commonly in use.
6.2 HDPE

HDPE (high density polyethylene) resin for geomembranes is a hydrocarbon polymer prepared from

ethylene/petroleum by a catalytic process. The molecular chains are linear, and the resin is semi-

crystalline. The geomembranes are produced by extrusion or blown film process and for stabilization

properties about 2 % carbon black is added. HDPE geomembranes have a very high resistance to

chemicals and the density is ≥ 0,940 g/cm .
6.3 LLDPE

LLDPE (linear low-density polyethylene) is a hydrocarbon polymer. The molecular chains are short and

branched. The density and crystallinity are lower than HDPE and therefore it is more flexible without

using plasticizer. The molecular chains are linear, and the resin is semi-crystalline. The geomembranes

are produced by extrusion or blown film process and for stabilization properties about 2 % carbon

3 3

black is added. The typical density for geomembranes is between 0,920 g/cm and 0,935 g/cm .

6.4 fPP

Flexible Polypropylene, fPP (per ASTM D4439) is a material having a 2 % secant modulus of less than

300 MPa (40 000 lb/in ) as determined by ASTM D5323 produced by polymerization of propylene with

or without other alpha olefin monomers.
6.5 PVC

PVC (polyvinyl chloride) geomembranes are produced from blends of rigid PVC and plasticizer

(Phthalate). The quantity of plasticizer, depending on the type, can be up to 40 %.

6.6 EPDM

EPDM (ethylene propylene diene monomer) geomembranes are made from synthetic rubber ethylene-

propylene-diene terpolymer, which is mixed with carbon black and other compounds, e.g. clay, oils,

processing aids. It is a vulcanized cross-linked rubber sheet.
6.7 Bitumen

Bituminous membranes mainly consist of a polymer/elastomeric blended bituminous layer on a

synthetic fabric. Bituminous geomembranes are between 3,0 mm and 5,0 mm thick and they can consist

of many different layers with different functions (sanded surface layer, polyester films).

6.8 EIA (ethylene interpolymer alloy)

EIA geomembranes consist of a PVC blend with a modifier on an ethylene copolymer basis. The modifier

resin increases the properties of the base resin, e.g. durability, flexibility.
6.9 Bentonite
Bentonite is an absorbent aluminium silicate clay formed from volcanic ash.
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6.10 Sodium bentonite

Sodium bentonite for use in geosynthetic clay barriers (GBR-C) is characterized by having sodium as its

predominant exchangeable ion. Sodium bentonite is not itself a mineral name, but more correctly, it is a

smectite clay composed primarily of the mineral montmorillonite.
6.11 Calcium bentonite

Calcium bentonite for use in geosynthetic Clay barriers (GBR-C) is characterized by having calcium as

its predominant exchangeable ion. Calcium bentonite is not itself a mineral name, but more correctly, it

is a smectite clay composed primarily of the mineral montmorillonite.
Table 2 considers appropriate compound selection in a given design.

Table 2 — Compound selection of a GBR to determine the suitability in a selected application

Barrier Type CA CC CW LBL LC SC TIA TU WRS-e WRS-f
GBR-P HDPE 1 1 2 1 1 1 1 2 1 1
LDPE 1 2 2 2 2 1 1 1 1 1
PVC 3 4 3 4 3 4 3 2 2 1
EPDM 3 4 3 4 3 4 3 3 1 1
PP 3 3 3 4 2 3 2 3 2 2
GBR-C Single-component 2 3 2 2 1 3 1 3 2 2
a a a a a a a a a a
Multi-component 2 2 2 2 1 2 1 2 2 2
GBR-B 3 3 2 4 3 3 2 2 2 2
Key
1: World-wide acceptance
2: General acceptance
3: Rarely used
4: Not recommended
Compare with the relevant combined component.
7 Properties relevant to design
7.1 General
7.1.1 For all designs the following basic parameters are relevant:
— Chemical resistance;
— Physical properties;
— Durability/weathering.

Most decision-making processes would typically come down to a combination of the above three

distinct parameters, essentially what the GBR is required to do, under what circumstances and for how

long. The expected lifetime of the GBR and the substrate is normally equivalent to design life.

7.1.2 Chemical resistance applies to:
— the material(s) from which the GBR is
...

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