FprEN ISO 11296-9

Plastics piping systems for renovation of underground non-pressure drainage and sewerage networks - Part 9: Lining with a rigidly anchored plastics inner layer (ISO/FDIS 11296-9:2022)

This document, in conjunction with ISO 11296‑1, specifies the requirements and test methods for pipes and fittings for the renovation of underground non-pressure drainage and sewerage networks by lining with a single rigid annulus of structural cementitious grout formed behind a plastics inner layer. This plastics layer serves as permanent formwork anchored to the grout.
This document is applicable to plastics inner layers and grout systems with or without steel reinforcement. It does not apply to the structural design of the lining system.
NOTE      Systems with multiple annuli are available, but these are controlled by patent rights and not covered by this document.

Kunststoff-Rohrleitungssysteme für die Renovierung von erdverlegten drucklosen Entwässerungsnetzen (Freispiegelleitungen) - Teil 9: Lining mit einer fest verankerten Kunststoffauskleidung (ISO/FDIS 11296-9:2022)

Dieses Dokument legt in Verbindung mit ISO 11296 1 die Anforderungen und Prüfverfahren für Rohre und Formstücke fest, die für die Renovierung erdverlegter druckloser Entwässerungsnetze (Freispiegelleitungen) durch Lining mit einem einzelnen biegesteifen Ringraum aus einem tragenden zementhaltigen Mörtel hinter einer Kunststoffauskleidung verwendet werden. Diese Kunststoffauskleidung dient als Dauerform, die mit dem Mörtel verankert ist.
Dieses Dokument ist anzuwenden für Kunststoffauskleidungen und Mörtelsysteme mit oder ohne Stahlbewehrung. Es behandelt nicht die statische Auslegung des Lining-Systems.
ANMERKUNG   Es gibt Systeme mit mehreren Ringräumen, die jedoch durch Patentrechte geschützt sind und in diesem Dokument nicht behandelt werden.

Systèmes de canalisations en plastique pour la rénovation des réseaux de branchements et de collecteurs d'assainissement enterrés sans pression - Partie 9: Tubage par coffrage plastique interne rigidement ancré (ISO/FDIS 11296-9:2022)

Le présent document, conjointement avec l’ISO 11296‑1, spécifie les exigences et les méthodes d’essai pour les tuyaux et raccords pour la rénovation des réseaux de branchements et de collecteurs d’assainissement enterrés sans pression par tubage avec un simple espace annulaire en coulis de ciment structurel formé derrière un coffrage plastique interne. Ce coffrage plastique sert de moule permanent ancré au coulis.
Le présent document est applicable aux coffrages plastiques internes et aux systèmes de coulis avec ou sans armature en acier. Il ne s’applique pas à la conception structurelle du système de tubage.
NOTE         Il existe des systèmes ayant plusieurs espaces annulaires, mais ils sont soumis à des droits de propriété industrielle et ne sont pas abordés par le présent document.

Cevni sistemi iz polimernih materialov za obnovo podzemnih omrežij za odvodnjavanje in kanalizacijo za obratovanje brez tlaka (vodi s prosto gladino) - 9. del: Oblaganje s trdno zasidrano notranjo plastjo iz plastike (ISO/FDIS 11296-9:2022)

General Information

• Status: Not Published
• ICS: 23.040.20 - Plastics pipes
• ICS: 23.040.45 - Plastics fittings
• ICS: 91.140.80 - Drainage systems
• ICS: 93.030 - External sewage systems
• Technical Committee: CEN/TC 165 - Waste water engineering
• Drafting Committee: CEN/TC 165/WG 13 - Renovation and repair of drains and sewers
• Ref Project: kSIST FprEN ISO 11296-9:2022 - Plastics piping systems for renovation of underground non-pressure drainage and sewerage networks - Part 9: Lining with a rigidly anchored plastics inner layer (ISO/FDIS 11296-9:2022)

Standards Content (sample)

SLOVENSKI STANDARD
oSIST prEN ISO 11296-9:2021
01-julij-2021
Cevni sistemi iz polimernih materialov za obnovo podzemnih omrežij za

odvodnjavanje in kanalizacijo za obratovanje brez tlaka (vodi s prosto gladino) - 9.

del: Oblaganje s trdno zasidrano notranjo plastjo iz plastike (ISO/DIS 11296-9:2021)

Plastics piping systems for renovation of underground non-pressure drainage and

sewerage networks - Part 9: Lining with a rigidly anchored plastics inner layer (ISO/DIS

11296-9:2021)
Kunststoff-Rohrleitungssysteme für die Renovierung von erdverlegten drucklosen

Entwässerungsnetzen (Freispiegelleitungen) - Teil 9: Lining mit einer fest verankerten

Kunststoffauskleidung (ISO/DIS 11296-9:2021)
Systèmes de canalisations en plastique pour la rénovation des réseaux de

branchements et de collecteurs d'assainissement enterrés sans pression - Partie 9:

Chemisage par revêtement de plastique interne rigidement ancré (ISO/DIS 11296-
9:2021)
Ta slovenski standard je istoveten z: prEN ISO 11296-9
ICS:
23.040.05 Cevovodi za zunanje Pipeline and its parts for
sisteme za odpadno vodo in external sewage systems
njihovi deli
91.140.80 Drenažni sistemi Drainage systems
93.030 Zunanji sistemi za odpadno External sewage systems
vodo
oSIST prEN ISO 11296-9:2021 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN ISO 11296-9:2021
---------------------- Page: 2 ----------------------
oSIST prEN ISO 11296-9:2021
DRAFT INTERNATIONAL STANDARD
ISO/DIS 11296-9
ISO/TC 138/SC 8 Secretariat: JISC
Voting begins on: Voting terminates on:
2021-05-21 2021-08-13
Plastics piping systems for renovation of underground
non-pressure drainage and sewerage networks —
Part 9:
Lining with a rigidly anchored plastics inner layer

Systèmes de canalisations en plastique pour la rénovation des réseaux de branchements et de collecteurs

d'assainissement enterrés sans pression —
Partie 9: Chemisage par revêtement de plastique interne rigidement ancré
ICS: 93.030; 23.040.45; 91.140.80; 23.040.20
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 11296-9:2021(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. ISO 2021
---------------------- Page: 3 ----------------------
oSIST prEN ISO 11296-9:2021
ISO/DIS 11296-9:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

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 2021 – All rights reserved
---------------------- Page: 4 ----------------------
oSIST prEN ISO 11296-9:2021
ISO/DIS 11296-9:2021(E)
Contents Page

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

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

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

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

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Symbols and abbreviations ....................................................................................................................................................................... 4

4.1 Symbols ......................................................................................................................................................................................................... 4

4.2 Abbreviations ........................................................................................................................................................................................... 5

5 Pipes at the “M” stage ...................................................................................................................................................................................... 5

5.1 Materials ....................................................................................................................................................................................................... 5

5.1.1 Product variants ............................................................................................................................................................... 5

5.1.2 Components of RAPL.................................................................................................................................................... 5

5.2 General characteristics ..................................................................................................................................................................... 7

5.3 Material characteristics ................................................................................................................................................................... 7

5.3.1 Material characteristics of studded PE sheet and PE profiled plastics strip ................ 7

5.3.2 Material characteristics of PVC-U profiled plastics strips ............................................................ 8

5.3.3 Material characteristics of seam sealant ..................................................................................................... 8

5.3.4 Material characteristics of the grout system ........................................................................................... 8

5.4 Geometric characteristics .............................................................................................................................................................. 9

5.4.1 General...................................................................................................................................................................................... 9

5.4.2 Studded PE sheet ............................................................................................................................................................. 9

5.4.3 Profiled plastics strips..............................................................................................................................................10

5.5 Mechanical characteristics.........................................................................................................................................................11

5.6 Physical characteristics ................................................................................................................................................................11

5.7 Jointing ........................................................................................................................................................................................................12

5.7.1 General...................................................................................................................................................................................12

5.7.2 Welding of studded PE sheet to form it into tube .............................................................................12

5.7.3 Mechanical jointing of spirally wound PVC-U plastics profiled strips ............................13

5.7.4 Mechanical jointing of PE plastics profile strips ...............................................................................14

5.8 Marking ......................................................................................................................................................................................................14

5.8.1 Marking of plastics inner layers.......................................................................................................................14

5.8.2 Marking of packaged or bulk containerised grout...........................................................................14

5.9 Regional requirements for pipes ..........................................................................................................................................14

6 Fittings at the “M” stage ..............................................................................................................................................................................15

6.1 General ........................................................................................................................................................................................................15

6.2 Materials ....................................................................................................................................................................................................15

6.3 Geometric characteristics ...........................................................................................................................................................15

7 Ancillary components ..................................................................................................................................................................................16

8 Fitness for purpose of the installed lining system at the “I” stage .................................................................16

8.1 Materials ....................................................................................................................................................................................................16

8.2 General characteristics ..................................................................................................................................................................16

8.3 Material characteristics ................................................................................................................................................................16

8.4 Geometric characteristics ...........................................................................................................................................................17

8.5 Mechanical characteristics.........................................................................................................................................................17

8.6 Physical characteristics ................................................................................................................................................................17

8.7 Additional characteristics ...........................................................................................................................................................17

8.8 Sampling ....................................................................................................................................................................................................17

9 Installation practice .......................................................................................................................................................................................18

9.1 Preparatory work ..............................................................................................................................................................................18

9.2 Storage, handling and transport of pipe components ........................................................................................18

9.3 Equipment ................................................................................................................................................................................................18

© ISO 2021 – All rights reserved iii
---------------------- Page: 5 ----------------------
oSIST prEN ISO 11296-9:2021
ISO/DIS 11296-9:2021(E)

9.4 Installation ...............................................................................................................................................................................................18

9.5 Process-related inspection and testing ...........................................................................................................................19

9.6 Lining termination ............................................................................................................................................................................19

9.7 Reconnection to existing laterals .........................................................................................................................................19

9.8 Final inspection and testing ......................................................................................................................................................19

9.9 Documentation ....................................................................................................................................................................................19

Annex A (normative) Test method for anchoring strength of plastics inner layer by pull-off ..............20

Annex B (normative) “I” stage crushing strength test .....................................................................................................................26

Bibliography .............................................................................................................................................................................................................................29

iv © ISO 2021 – All rights reserved
---------------------- Page: 6 ----------------------
oSIST prEN ISO 11296-9:2021
ISO/DIS 11296-9:2021(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 138, Plastics pipes, fittings and valves for

the transport of fluids, Subcommittee SC 8, Rehabilitation of pipeline systems.
A list of all parts in the ISO 11296 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.
© ISO 2021 – All rights reserved v
---------------------- Page: 7 ----------------------
oSIST prEN ISO 11296-9:2021
ISO/DIS 11296-9:2021(E)
Introduction

This document is a part of a System Standard for plastics piping systems of various materials used for

the renovation of existing pipelines in a specified application area. System Standards for renovation

deal with the following applications:

— ISO 11296, Plastics piping systems for renovation of underground non-pressure drainage and sewerage

networks (this application);

— ISO 11297, Plastics piping systems for renovation of underground drainage and sewerage networks

under pressure;

— ISO 11298, Plastics piping systems for renovation of underground water supply networks;

— ISO 11299, Plastics piping systems for renovation of underground gas supply networks.

These System Standards are distinguished from those for conventionally installed plastics piping

systems by the requirement to verify certain characteristics in the “as-installed condition”, after site

processing. This is in addition to specifying requirements for plastics piping system components “as

manufactured”.
Each of the System Standards comprises a:
— Part 1: General

and all applicable renovation technique family-related parts, which for non-pressure drainage and

sewerage networks include or potentially include the following:
— Part 2: Lining with continuous pipes;
— Part 3: Lining with close-fit pipes;
— Part 4: Lining with cured-in-place pipes;
— Part 5: Lining with discrete pipes;
— Part 7: Lining with spirally-wound pipes;
— Part 8: Lining with pipe segments;
— Part 9: Lining with rigidly anchored plastics inner layer (this document);
— Part 10: Lining with sprayed polymeric materials.

The requirements for any given renovation technique family are specified in part 1, applied in

conjunction with the relevant other part. For example, both ISO 11296-1 and this document

together specify the requirements relating to lining with a rigidly anchored plastics inner layer. For

complementary information, see ISO 11296-1. Not all technique families are pertinent to every area of

application and this is reflected in the part numbers included in each System Standard.

A consistent structure of clause headings has been adopted for all parts of ISO 11296, in order to

facilitate direct comparisons across renovation technique families.

Figure 1 shows the common part and clause structure and the relationship between ISO 11296-1 and

the System Standards for other application areas.
vi © ISO 2021 – All rights reserved
---------------------- Page: 8 ----------------------
oSIST prEN ISO 11296-9:2021
ISO/DIS 11296-9:2021(E)
Figure 1 — Format of the renovation system standards
© ISO 2021 – All rights reserved vii
---------------------- Page: 9 ----------------------
oSIST prEN ISO 11296-9:2021
---------------------- Page: 10 ----------------------
oSIST prEN ISO 11296-9:2021
DRAFT INTERNATIONAL STANDARD ISO/DIS 11296-9:2021(E)
Plastics piping systems for renovation of underground
non-pressure drainage and sewerage networks —
Part 9:
Lining with a rigidly anchored plastics inner layer
1 Scope

This document, in conjunction with ISO 11296-1, specifies requirements and test methods for pipes

and fittings for the renovation of underground non-pressure drainage and sewerage networks by lining

with a single rigid annulus of structural cementitious grout formed behind a plastics inner layer. This

plastics layer serves as permanent formwork anchored to the grout.

This document is applicable to plastics inner layers and grout systems with or without steel

reinforcement. It does not apply to the structural design of the lining system.

NOTE Systems with multiple annuli are available, but these are controlled by patent rights and not covered

by this document.
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 306, Plastics — Thermoplastic materials — Determination of Vicat softening temperature (VST)

ISO 37, Rubber, vulcanized or thermoplastic — Determination of tensile stress-strain properties

ISO 48-4, Rubber, vulcanized or thermoplastic — Determination of hardness — Part 4: Indentation

hardness by durometer method (Shore hardness)

ISO 75-2:2013, Plastics — Determination of temperature of deflection under load — Part 2: Plastics

and ebonite

ISO 527-2:2012, Plastics — Determination of tensile properties — Part 2: Test conditions for moulding and

extrusion plastics

ISO 1133-1:2011, Plastics — Determination of the melt mass-flow rate (MFR) and melt volume-flow rate

(MVR) of thermoplastics — Part 1: Standard method

ISO 1133-2:2011, Plastics — Determination of the melt mass-flow rate (MFR) and melt volume-flow rate

(MVR) of thermoplastics — Part 2: Method for materials sensitive to time-temperature history and/or

moisture

ISO 1183-1, Plastics — Methods for determining the density of non-cellular plastics — Part 1: Immersion

method, liquid pycnometer method and titration method
ISO 4624:2003, Paints and varnishes — Pull-off test for adhesion

ISO 4948-2, Steels — Classification — Part 2: Classification of unalloyed and alloy steels according to main

quality classes and main property or application characteristics
ISO 6316, Hot-rolled steel strip of structural quality
© ISO 2021 – All rights reserved 1
---------------------- Page: 11 ----------------------
oSIST prEN ISO 11296-9:2021
ISO/DIS 11296-9:2021(E)
ISO 6935 (series), Steel for the reinforcement of concrete

ISO 11296-1:2018, Plastics piping systems for renovation of underground non-pressure drainage and

sewerage networks — Part 1: General

ISO 11296-7:2019, Plastics piping systems for renovation of underground non-pressure drainage and

sewerage networks — Part 7: Lining with spirally-wound pipes

ISO 11357-6, Plastics — Differential scanning calorimetry (DSC) — Part 6: Determination of oxidation

induction time (isothermal OIT) and oxidation induction temperature (dynamic OIT)

ISO 13262, Thermoplastics piping systems for non-pressure underground drainage and sewerage —

Thermoplastics spirally-formed structured-wall pipes — Determination of the tensile strength of a seam

EN 196-1, Methods of testing cement — Part 1: Determination of strength
EN 445:2007, Grout for prestressing tendons — Test methods

EN 1015-3, Methods of test for mortar for masonry — Part 3: Determination of consistence of fresh mortar

(by flow table)

EN 1015-6, Methods of test for mortar for masonry — Part 6: Determination of bulk density of fresh mortar

EN 1107-2, Flexible sheets for waterproofing — Determination of dimensional stability — Part 2: Plastic

and rubber sheets for roof waterproofing

EN 1542:1999, Products and systems for the protection and repair of concrete structures — Test methods —

Measurement of bond strength by pull-off
EN 1610:1997, Construction and testing of drains and sewers

EN 1916:2002, Concrete pipes and fittings, unreinforced, steel fibre and reinforced

EN 10025-1, Hot rolled products of structural steels — Part 1: General technical delivery conditions

EN 10025-2, Hot rolled products of structural steels — Part 2: Technical delivery conditions for non-alloy

structural steels
EN 10048, Hot rolled narrow steel strip — Tolerances on dimensions and shape

EN 12814-2, Testing of welded joints of thermoplastics semi-finished products — Part 2: Tensile test

EN 12814-8, Testing of welded joints of thermoplastics semi-finished products — Part 8: Requirements

EN 13067, Plastics welding personnel - Qualification testing of welders — Thermoplastics welded assemblies

EN 13100-4, Non-destructive testing of welded joints of thermoplastics semi-finished products — Part 4:

High voltage testing

EN 13412, Products and systems for the protection and repair of concrete structures — Test methods —

Determination of modulus of elasticity in compression

EN 14117, Products systems for the protection and repair of concrete structures — Test methods —

Determination of time of efflux of cementitious injection products

EN 14654-1:2014, Management and control of operational activities in drain and sewer systems outside

buildings — Part 1: Cleaning

CEN/TR 14920, Jetting resistance of drain and sewer pipes — Moving jet test method

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 11296-1 and the following apply.

2 © ISO 2021 – All rights reserved
---------------------- Page: 12 ----------------------
oSIST prEN ISO 11296-9:2021
ISO/DIS 11296-9:2021(E)

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 https:// www .electropedia .org/
3.1
lining with a rigidly anchored plastics inner layer

lining with pipe comprising a single rigid annulus of structural cementitious grout and a plastics inner

layer anchored to the grout
3.2
anchored plastics inner layer

layer with integral anchors which forms the inside surface of the pipe after installation

3.3
profiled plastics strip

extruded profile of PVC-U or PE, with integral or separate seam locking mechanism, used to form

waterway wall of a pipe liner
3.4
joiner strip
extruded profile of PVC-U or PE used to connect adjacent profiled plastic strips
3.5
seam

joint between adjacent profiled plastics strips formed by an integral locking mechanism, use of a

separate joiner strip, and/or seam sealant (3.7)
3.6
integral locking mechanism

mechanical interlock achieved by suitable design of the edges of the extruded profile, without use of a

separate joiner strip
3.7
seam sealant

thermoplastic or adhesive material added to the integral locking mechanism (3.6), joiner strip (3.4) or

profiled plastics strip (3.3) surface to make the seam leaktight
3.8
studded PE sheet
polyethylene sheet with integral anchoring studs
3.9
lateral connection collar

fitting for reconnecting a lined main pipe to an existing or renovated lateral pipe

3.10
annular space

gap between the plastics inner layer and either the host pipe or the external layer where present

3.11
reinforcement

steel bars incorporated in the grout or steel stiffening elements placed alongside or encapsulated

within the plastics inner layer
3.12
grout system

cement-based grout including any fillers, reinforcement (3.11) or other additives or admixtures, in

specified proportions
© ISO 2021 – All rights reserved 3
---------------------- Page: 13 ----------------------
oSIST prEN ISO 11296-9:2021
ISO/DIS 11296-9:2021(E)
3.13
design thickness

combined thickness of plastics inner layer and grouted annulus required by structural design

3.14
spacer

block of material compatible with grout system (3.12) used to maintain minimum thickness of annular

space (3.10) and prevent flotation of inner plastics layer during filling with grout

4 Symbols and abbreviations

For the purpose of this document, the symbols and abbreviated terms given in ISO 11296-1 and the

following apply.
4.1 Symbols
A cross-sectional area of the profiled plastics strip
b width of air test channel
d minimum outside diameter of inner plastics layer in circular pipes
e,min
e overall height of anchored plastics inner layer
e waterway wall thickness
e height of neutral axis of the strip above its base
e minimum thickness of grout above height of anchors

e thickness of plastic at any point over the top (short side) of an encapsulated steel strip

e thickness of plastic at any point over the height (long side) of an encapsulated steel strip

f bending tensile stress from crushing strength
f anchoring strength of plastics inner layer
I second moment of area of the strip
R compressive strength after 28 days
c,28
R flexural strength after 28 days
f,28
r minimum local radius of curvature of inner plastics layer in non-circular pipe
e,min
w effective width of the strip

Δε Change of length of test prism of cement mortar exposed to sulphate attack relative to that of

a c
...