EN ISO 12958-1:2020

• Abstract:

  This document specifies a method for determining the constant-head water flow capacity within the plane of a geotextile or geotextile-related product. This document describes the in-plane water flow index test, only applicable to factory-assembled products. For the in-plane water flow performance test, see ISO 12958-2.

• Status: Published
• Publication Date: 03-Nov-2020
• Withdrawal Date: 30-May-2021
• ICS: 59.080.70 - Geotextiles
• Technical Committee: CEN/TC 189 - Geotextiles and geotextile-related products
• Drafting Committee: CEN/TC 189/WG 4 - Hydraulic testing
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 04-Nov-2020
• Completion Date: 04-Nov-2020
• Directive: Harmonized Standard305/2011 - Regulation (eu) No 305/2011 of the European Parliament and of the Council of 9 march 2011 laying down harmonised conditions for the marketing of construction products and repealing council directive 89/106/eec
• Mandate: M/107 - Mandate to CEN/CENELEC concerning the execution of standardization work for harmonized standards on geotextiles
• Ref Project: SIST EN ISO 12958-1:2021 - Geotextiles and geotextile-related products - Determination of water flow capacity in their plane - Part 1: Index test (ISO 12958-1:2020)

• Replaces: EN ISO 12958:2010 - Geotextiles and geotextile-related products - Determination of water flow capacity in their plane (ISO 12958:2010)
• Effective Date: 08-Jun-2022
• Refers: ISO 5813:1983 - Water quality — Determination of dissolved oxygen — Iodometric method
• Effective Date: 25-Aug-2026
• Refers: ISO 2854:1976 - Statistical interpretation of data — Techniques of estimation and tests relating to means and variances
• Effective Date: 25-Aug-2026
• Refers: ISO 10320:2019 - Geosynthetics — Identification on site
• Effective Date: 25-Aug-2026
• Refers: ISO 9862:2005 - Geosynthetics — Sampling and preparation of test specimens
• Effective Date: 25-Aug-2026
• Refers: ISO 9863-1:2016 - Geosynthetics — Determination of thickness at specified pressures — Part 1: Single layers
• Effective Date: 25-Aug-2026
• Refers: EN 437:2018 - Test gases - Test pressures - Appliance categories
• Effective Date: 28-Jan-2026
• Refers: EN ISO 16546:2020 - Thermal insulating products for building applications - Determination of freeze-thaw resistance (ISO 16546:2020)
• Effective Date: 28-Jan-2026
• Refers: EN 1744-1:2009/FprA1 - Tests for chemical properties of aggregates - Part 1: Chemical analysis
• Effective Date: 28-Jan-2026
• Refers: EN 14762:2006 - Wood flooring - Sampling procedures for evaluation of conformity
• Effective Date: 28-Jan-2026
• Refers: EN ISO 4892-2:1999 - Plastics - Methods of exposure to laboratory light sources - Part 2: Xenon-arc sources (ISO 4892-2:1994)
• Effective Date: 28-Jan-2026
• Referred By: EN 13252:2016 - Geotextiles and geotextile-related products - Characteristics required for use in drainage systems
• Effective Date: 28-Jan-2026
• Referred By: EN 12616:2023 - Surfaces for sports areas - Test methods for the determination of vertical water infiltration and horizontal water flow rates
• Effective Date: 28-Jan-2026
• Referred By: EN 13252:2014 - Geotextiles and geotextile-related products - Characteristics required for use in drainage systems
• Effective Date: 28-Jan-2026
• Referred By: EN 13252:2014+A1:2015 - Geotextiles and geotextile-related products - Characteristics required for use in drainage systems
• Effective Date: 28-Jan-2026

Overview

EN ISO 12958-1:2020 specifies a standardized index test for measuring the constant-head in-plane water flow capacity of geotextiles and geotextile-related products. The method determines the volumetric flow rate of water per unit width under defined normal compressive stresses and hydraulic gradients. This part (ISO 12958-1) is an index test intended for factory‑assembled products; full performance testing is covered separately in ISO 12958-2.

Key topics and technical requirements

• Test principle: constant-head measurement of water flow parallel to the plane of the specimen, reported as flow capacity (q_p_index) in (l/s)/m.
• Hydraulic gradients: apparatus must maintain head losses corresponding at least to hydraulic gradients of 0.1 and 1.0.
• Normal compressive stress: test applies controlled normal stresses; loading mechanism accuracy required to be within ±5% of the applied stress.
• Contact surface (boundary) types: three permitted contact configurations - foam/foam (F/F), rigid/foam (R/F), or rigid/rigid (R/R) - with specific foam and rigid liner requirements.
• Foam specification: recommended foam thickness linked to specimen thickness:
  • up to 10 mm specimen → 10 mm foam each face
  • 10–25 mm specimen → foam 1.0–1.25× specimen thickness

  • 25 mm specimen → 25 mm foam each face

  • two-layer foam allowed only when individual foam sheets exceed 10 mm
• Apparatus limits: discharge head must not exceed 100 mm; if average water head exceeds 100 mm and applied load ≤ 20 kPa, corrections to normal stress are required.
• Terminology: prefers term “water flow capacity” (accounts for non-laminar flow) rather than transmissivity which assumes laminar flow.
• Reporting and calculations: procedures for specimen selection, conditioning, measurement, conversions (e.g., temperature correction) and graphical representation are defined.

Applications and users

This standard is important for:

• Manufacturers of geotextiles and geocomposites - for factory quality control and product data sheets.
• Independent test laboratories - for reproducible index testing and comparative reporting.
• Design engineers and specifiers - to select materials with appropriate in-plane drainage capacity for applications such as drainage layers, landfill liners, road and railway substructures, and retaining structures.
• Regulatory bodies and procurement teams - for harmonized test evidence when assessing in-plane drainage performance.

Keywords: geotextiles, in-plane water flow, water flow capacity, index test, ISO 12958-1, constant-head, hydraulic gradient, geosynthetics.

Related standards

• ISO 12958-2 - in-plane water flow performance test
• ISO 9862 - sampling and specimen preparation
• ISO 9863-1 - thickness determination (single layers)
• ISO 2854, ISO 5813, ISO 10320 - referenced test methods and statistical guidance
• ISO/TR 18228-4 (informative reference on hydraulic gradient significance)

SLOVENSKI STANDARD
01-januar-2021
Nadomešča:
SIST EN ISO 12958:2012
Geotekstilije in geotekstilijam sorodni izdelki - Ugotavljanje zmogljivosti pretoka
vode v ravnini - 1. del: Indeksni preskus (ISO 12958-1:2020)
Geotextiles and geotextile-related products - Determination of water flow capacity in their
plane - Part 1: Index test (ISO 12958-1:2020)
Geotextilien und geotextilverwandte Produkte - Bestimmung des
Wasserableitvermögens in der Ebene - Teil 1: Index-Prüfverfahren (ISO 12958-1:2020)
Géotextiles et produits apparentés - Détermination de la capacité de débit dans leur plan
- Partie 1: Essai index (ISO 12958-1:2020)
Ta slovenski standard je istoveten z: EN ISO 12958-1:2020
ICS:
59.080.70 Geotekstilije Geotextiles
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 12958-1
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2020
EUROPÄISCHE NORM
ICS 59.080.70 Supersedes EN ISO 12958:2010
English Version
Geotextiles and geotextile-related products -
Determination of water flow capacity in their plane - Part
1: Index test (ISO 12958-1:2020)
Géotextiles et produits apparentés - Détermination de Geotextilien und geotextilverwandte Produkte -
la capacité de débit dans leur plan - Partie 1: Essai Bestimmung des Wasserableitvermögens in der Ebene
index (ISO 12958-1:2020) - Teil 1: Index-Prüfverfahren (ISO 12958-1:2020)
This European Standard was approved by CEN on 12 October 2020.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 12958-1:2020 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 12958-1:2020) has been prepared by Technical Committee ISO/TC 221
"Geosynthetics" in collaboration with Technical Committee CEN/TC 189 “Geosynthetics” the secretariat
of which is held by NBN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by May 2021, and conflicting national standards shall be
withdrawn at the latest by May 2021.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 12958:2010.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 12958-1:2020 has been approved by CEN as EN ISO 12958-1:2020 without any
modification.
INTERNATIONAL ISO
STANDARD 12958-1
First edition
2020-10
Geotextiles and geotextile-related
products — Determination of water
flow capacity in their plane —
Part 1:
Index test
Géotextiles et produits apparentés — Détermination de la capacité de
débit dans leur plan —
Partie 1: Essai index
Reference number
ISO 12958-1:2020(E)
©
ISO 2020
ISO 12958-1:2020(E)
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

ISO 12958-1:2020(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus and materials. 2
6 Specimens . 6
6.1 Handling. 6
6.2 Selection. 6
6.3 Number and dimensions . 6
6.4 Specimen condition . 7
7 Test procedure . 7
8 Calculations and expression of results . 8
8.1 Products with a continuous structure (i.e. with no discrete draining elements) . 8
8.2 Products with discrete draining elements . 8
8.3 Graphical representation . 9
9 Test report .10
Annex A (informative) Determination of the correction factor R for conversion to a water
T
temperature of 20 °C .11
Annex B (informative) Experimental data and calculations for a specimen .13
Bibliography .14
ISO 12958-1:2020(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, in collaboration with
the European Committee for Standardization (CEN) Technical Committee CEN/TC 189, Geosynthetics,
in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This first edition of ISO 12958-1, together with ISO 12958-2, cancels and replaces ISO 12958:2010,
which has been technically revised.
The main changes to ISO 12958:2010 are as follows:
— introduction of the concept of index versus performance test;
— permission given to test using rigid/rigid, soft/soft or soft/rigid boundaries;
— addition of guidance for testing cuspated sheets on a single side and for testing multilinear drainage
geocomposites;
— withdrawal of apparatus types b) and c);
— several cosmetic improvements, in particular terms and definitions, procedure, calculation and
reporting.
A list of all parts in the ISO 12958 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.
iv © ISO 2020 – All rights reserved

INTERNATIONAL STANDARD ISO 12958-1:2020(E)
Geotextiles and geotextile-related products —
Determination of water flow capacity in their plane —
Part 1:
Index test
1 Scope
This document specifies a method for determining the constant-head water flow capacity within the
plane of a geotextile or geotextile-related product. This document describes the in-plane water flow
index test, only applicable to factory-assembled products. For the in-plane water flow performance test,
see ISO 12958-2.
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 2854, Statistical interpretation of data — Techniques of estimation and tests relating to means and
variances
ISO 5813, Water quality — Determination of dissolved oxygen — Iodometric method
ISO 9862, Geosynthetics — Sampling and preparation of test specimens
ISO 9863-1, Geosynthetics — Determination of thickness at specified pressures — Part 1: Single layers
ISO 10320, Geosynthetics — Identification on site
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
normal compressive stress
σ
compressive stress normal to the plane of the geotextile or geotextile-related product, expressed in
kilopascals [kPa]
3.2
in-plane flow
Q
fluid flow within the geotextile or geotextile-related product and parallel to its plane, expressed in
litres per second [l/s]
ISO 12958-1:2020(E)
3.3
in-plane water flow capacity
q
p index(σ/i)
volumetric flow rate of water per unit width of specimen at a defined normal compressive stress (σ),
hydraulic gradient (i), measured in the present index test and expressed in litres per second per meter
[(l/s)/m]
Note 1 to entry: The term 'transmissivity' is related to laminar flow conditions only and equals the water flow
capacity at a hydraulic gradient equal to unity. As non-laminar flow may occur, the term 'water flow capacity' is
preferred.
3.4
hydraulic gradient
i
ratio of the head loss in the geotextile or geotextile-related product specimen to the distance between
two measuring points within the geotextile or geotextile-related product
1)
Note 1 to entry: ISO/TR 18228-4 provides information on the significance of the hydraulic gradient.
3.5
contact surface
surface contacting the specimen
Note 1 to entry: Contact surfaces may be either closed-cell foam rubber on both sides (F/F), smooth rigid
membrane on one side and closed-cell foam rubber on the other side (R/F) or smooth rigid membrane on both
sides (R/R).
3.6
in-plane water flow index test
test that yields an indication of the in-plane water flow
3.7
in-plane water flow performance test
test to confirm full compliance of the in-plane water flow with the requirements under specified
conditions
4 Principle
The flow of water within the plane of a geotextile or geotextile-related product is measured under
varying normal compressive stresses, with typical hydraulic gradients and with defined contact
surfaces.
5 Apparatus and materials
5.1 Constant-head in-plane water flow apparatus, as follows:
a) The apparatus shall be capable of maintaining a constant head loss at different water levels, at least
those corresponding to hydraulic gradients of 0,1 and 1,0, while maintaining a water head at the
point of discharge not greater than 100 mm.
b) If the average water head above the specimen exceeds 100 mm, and the applied normal load is
equal to or less than 20 kPa, the normal stress shall be corrected for the excess considering the
average water head.
c) The apparatus shall be capable of maintaining the proposed normal compressive stress on the
specimen without any deformation which would influence the test results.
1) Under preparation. Stage at the time of publication: ISO/CD TR 18228-4:2020.
2 © ISO 2020 – All rights reserved

ISO 12958-1:2020(E)
d) The apparatus shall include a loading mechanism capable of exerting a constant normal compressive
stress on the geotextile or geotextile-related product specimen to a maximum permissible error
of ± 5 % of applied normal compressive stress.
e) The surfaces contacting the specimen should be either:
— foam rubber (F) whose properties should satisfy the compression deflection envelope,
illustrated in Figure 1, when tested in accordance with ISO 9863-1; or
— smooth rigid (R) high-density polyethylene liner 2 mm thick without any surface damage.
Performances of a geotextile-related product with any other bound
...