General practices for the repair of water-leakage cracks in concrete structures

This document provides a guideline for the selection of a proper grout material to repair water leakage through cracks and other deformities in concrete structures. The factors relevant to the quality control of maintenance and repair of water-leakage cracks are as the following; a) conditions of water-leakage cracks; b) performance requirements for repair materials; c) different types of repair materials (grouts); d) procedures followed to select the appropriate repair materials; e) execution of different types of repair methods; f) performance assessments of applied materials and methods; g) data collection. This document does not include any details on the repair of dry cracks and the causes of cracks. The details on dry crack repair are covered in ISO 16311-4. A flow chart for maintenance of water-leakage cracks is shown in Figure 1.

Pratiques générales pour la répartition des fissures dues à l'eau dans les structures en béton

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Publication Date
19-Mar-2020
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6060 - International Standard published
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20-Mar-2020
Completion Date
20-Mar-2020
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TECHNICAL ISO/TR
REPORT 16475
Second edition
2020-03
General practices for the repair of
water-leakage cracks in concrete
structures
Pratiques générales pour la répartition des fissures dues à l'eau dans
les structures en béton
Reference number
ISO/TR 16475:2020(E)
ISO 2020
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ISO/TR 16475:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

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Published in Switzerland
ii © ISO 2020 – All rights reserved
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ISO/TR 16475:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

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

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

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

4 Conditions of water-leakage cracks .................................................................................................................................................. 2

4.1 Types of water-leakage cracks .................................................................................................................................................. 2

4.2 Environmental degradation factors that cause water-leakage cracks .................................................... 3

4.2.1 General...................................................................................................................................................................................... 3

4.2.2 Chemical conditions ...................................................................................................................................................... 4

4.2.3 Physical (mechanical) conditions...................................................................................................................... 4

5 Expected performance for repair materials ............................................................................................................................ 5

5.1 General ........................................................................................................................................................................................................... 5

5.2 Expected performance for chemical conditions ......................................................................................................... 5

5.2.1 Thermal stability.............................................................................................................................................................. 5

5.2.2 Chemical resistance ....................................................................................................................................................... 5

5.3 Expected performance for physical (mechanical) conditions ........................................................................ 5

5.3.1 Water (wash out) resistance .................................................................................................................................. 5

5.3.2 Adhesion on wet substrate surface .................................................................................................................. 5

5.3.3 Watertightness .................................................................................................................................................................. 6

5.3.4 Response to the substrate movement ........................................................................................................... 6

6 Grout materials for repair .......................................................................................................................................................................... 6

6.1 General ........................................................................................................................................................................................................... 6

6.2 Acrylic grouts (water-based acrylic gel grout) ............................................................................................................ 7

6.3 Cementitious grouts (water-based mixture of cement grout) ....................................................................... 7

6.4 Epoxy resin grout .................................................................................................................................................................................. 8

6.5 Polyurethane grouts ........................................................................................................................................................................... 8

6.6 Synthetic rubber polymer gel grout...................................................................................................................................... 8

6.7 Other materials ....................................................................................................................................................................................... 8

7 Appropriate repair material selection procedure ............................................................................................................ 9

7.1 Selection process of repair materials (injection grouts) .................................................................................... 9

7.2 Test for performance requirements...................................................................................................................................... 9

7.2.1 General...................................................................................................................................................................................... 9

7.2.2 Test for thermal stability .......................................................................................................................................10

7.2.3 Test for chemical resistance ................................................................................................................................10

7.2.4 Test for water flow (wash out) resistance ..............................................................................................10

7.2.5 Test for adhesion on wet substrate surface ...........................................................................................10

7.2.6 Test for watertightness ............................................................................................................................................11

7.2.7 Test for response to the substrate movement .....................................................................................11

8 Execution of different types of repair methods .................................................................................................................11

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

8.2 Grouting injection methods ......................................................................................................................................................11

8.3 Injection method for reforming a waterproofing layer .....................................................................................12

9 Performance assessments of repaired structures ..........................................................................................................13

9.1 Inspection of repairs .......................................................................................................................................................................13

9.2 Evaluation of repairs .......................................................................................................................................................................13

10 Data collection (reference material) ............................................................................................................................................14

Bibliography .............................................................................................................................................................................................................................15

© ISO 2020 – All rights reserved iii
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ISO/TR 16475:2020(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 71, Concrete, reinforced concrete and pre-

stressed concrete, Subcommittee SC 7, Maintenance and repair of concrete structures.

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
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ISO/TR 16475:2020(E)
Introduction

This document is intended to provide an informative outline of practice for the repair of water-leakage

cracks of concrete structures. There are two types of cracks that can form in a concrete structure; dry

cracks and water-leakage (wet) cracks. Cracks normally form when the structural element is subject

to phenomena such as dry-shrinkage and formation of joints. In the typical above grade sections of the

concrete structure, dry cracks are more easily controlled and repaired with a well-defined maintenance

method. When cracks are formed by the effect of hydrostatic pressure and the interface of the crack

is subject to constant wetness, these cracks are designated as water-leakage cracks. The ingress of

water through cracks often leads to increase of humidity in the building interior and this can result

in a drastically accelerated degradation of durability for the concrete structure. In extreme cases, the

presence of water can generate harmful effects that cause health problems to the users, rendering the

building completely uninhabitable.

In the current state, it is difficult to secure a proper repair method of water-leakage cracks because of

insufficient knowledge and understanding of the degradation factors (i.e. environmental conditions,

the influences of various human activities, etc.), at an institutional level. There are already a number

of repair techniques and application methods that are commonly used in application, but the required

conditions for properly repairing and sealing the water-leakage cracks have often been proven to be

difficult. Even in some cases where the repair procedures have been followed through properly with

skilled workmanship, the performance level of the repair method may be insufficient and lead to

reopening of the leakage crack. This can in turn lead to increase in maintenance and labour costs and

decrease in the property value of the building structures.

Past records of remedial actions for cracks and damage in concrete structures have shown varying

degrees of results; some have shown failure, some have had minor success and, in some cases,

an adequate solution was implemented. However, the cases of successful repair methods cannot

serve as a universal model for all cases of cracks and leakage due to the diversity of environmental

degradation factors existing in the construction field. In this regard, a standardized practice for

selecting appropriate leakage repair materials and methods in construction sites can be used. It is

highly anticipated that a newly proposed awareness and understanding of these issues will prevent

further unnecessary increase in maintenance costs, expenditures and results in improved durability

performance of concrete structures.
© ISO 2020 – All rights reserved v
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TECHNICAL REPORT ISO/TR 16475:2020(E)
General practices for the repair of water-leakage cracks in
concrete structures
1 Scope

This document provides a guideline for the selection of a proper grout material to repair water leakage

through cracks and other deformities in concrete structures. The factors relevant to the quality control

of maintenance and repair of water-leakage cracks are as the following;
a) conditions of water-leakage cracks;
b) performance requirements for repair materials;
c) different types of repair materials (grouts);
d) procedures followed to select the appropriate repair materials;
e) execution of different types of repair methods;
f) performance assessments of applied materials and methods;
g) data collection.

This document does not include any details on the repair of dry cracks and the causes of cracks. The

details on dry crack repair are covered in ISO 16311-4.
A flow chart for maintenance of water-leakage cracks is shown in Figure 1.
Figure 1 — Flow chart for maintenance of water-leakage chart
© ISO 2020 – All rights reserved 1
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ISO/TR 16475:2020(E)
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 16311-2, Maintenance and repair of concrete structures — Part 2: Assessment of existing concrete

structures
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 16311-2 and the following 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
water-leakage crack

gap or split in a concrete substrate accompanied by intermittent or continuous contact of water present

across the interface of the gap/split surface
3.2
leakage

amount or flowing state of liquid(water) that is entering into the interior of the concrete structure by

means of a crack, hole, joint or other structural fault
3.3
thermal stability
ability to withstand long time exposure to elevated temperature
[SOURCE: IEC 60050:2010, 212-12-32]
3.4
washout resistance

property of the water-leakage crack (3.1) repair material related to the ability to withstand quantitative

and qualitative loss of materials produced by the pressure and flow velocity of water

3.5
watertightness

repair material’s waterproofing performance in consideration to its impermeability, adhesion strength

to the concrete substrate surface and cohesive strength, while being subject to the influence of

hydrostatic pressure
4 Conditions of water-leakage cracks
4.1 Types of water-leakage cracks

Leakage type and degree, and crack size (width) classification can be difficult as there are variances

in leakage crack control methods with different repair material and methods. Leakage types can be

classified as damp, seepage and flow, but specific amount of water leakage for the corresponding

leakage types also varies. Optimal grout injection method and material selection through evaluation

and testing can be applied for the respective classification of cracks (fine, medium and large cracks) in

relation to different leakage types and degrees (damp, seepage and flow). In this document, a leakage

type and degree classification system from ICRI 340.1-2006 is provided. The reference also provides

an information on the possible crack size classification (crack width) that corresponds to the leakage

types and degrees. This information is provided in Table 1.
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ISO/TR 16475:2020(E)

Table 1 — Classification of cracks in relation to repair of water-leakage (example)

Type of crack Patterns of leakage
Non-moving crack —
Damp surface
Light seepage
<1 l/min (<1/4 gal/min)
Medium seepage
Fine cracks
>1 l/min to 5 l/min (>1/4 gal/min to 1 1/4 gal/min)
≤2 mm (≤1/13 in)
Heavy seepage
Medium cracks
>5 l/min to 10 l/min (>1 1/4 gal/min to 2 1/2 gal/min)
>2 mm to 6 mm (>1/13 in to 1/4 in)
Light flow
Large cracks
>10 l/min to 15 l/min (>2 1/2 gal/min to 4 gal/min)
>6 mm to 20 mm (>1/4 in to 10/13 in)
Medium flow
>15 l/mm to 25 l/min (>4 gal/min to 6 1/2 gal/min)
Heavy flow
>25 l/min (>6 1/2 gal/min)

NOTE 1 Each and every crack width in the left column corresponds to the leakage amount conditions specified in the right-

side column.

NOTE 2 Leakage types and degrees, and crack sizes (width) can differ in national standards.

4.2 Environmental degradation factors that cause water-leakage cracks
4.2.1 General

Unlike dry cracks, water-leakage cracks are often caused by exposure to certain environmental-related

(chemical and physical) degradation factors that are caused by nature. These factors are: temperature

and humidity in the atmosphere and concrete surface, water pressure, flow velocity, chemical reactions

of the water and various forms of mechanical loads (e.g. vibration caused by passing vehicles). When in

the presence of one or more these environmental factors in a concrete structure, structural degradation

accelerates and negatively affects performance level of repair (see Figure 2).
© ISO 2020 – All rights reserved 3
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ISO/TR 16475:2020(E)

Figure 2 — Environmental conditions and required performance for water-leakage crack repairs

Water-leakage cracks are constantly subject to a variety of environmental degradation factors. In order

to establish a proper response to degradation factors that exist in the surrounding environment, it is

important to select the appropriate repair materials and methods.

Based on the types of environmental factors found in the concrete structure surroundings, the types

of possible defects such as material adhesion failure, waterproofing layer delamination or material

cracking can be estimated. Potential sources of degradation can be clearly identified and repair

materials with the required performance level that can respond to these degradation factors is selected

accordingly. Finally, the installation process can be observed and evaluated to determine that the repair

material can maintain a long-term quality performance while subject to constant exposure to the given

environmental degradation condition.

Figure 2 categorizes the environmental degradation factors into the relevant categories and outlines

the required material properties.
4.2.2 Chemical conditions

Chemical factors that affect the performance of repair materials in water-leakage cracks include

temperature changes and ambient conditions of the water-leakage cracks and the chemical composition

of the water (e.g. underground water, salt water, sewage water and acid rain). These factors affect

thermal stability, resistance to chemical attack, watertightness and the adhesion performance of repair

material on the concrete substrate surface.
4.2.3 Physical (mechanical) conditions

The physical (mechanical) factors that affect the performance of repair materials in water-leakage

cracks include the movement of the concrete substrate joints or cracks, shrinkage and expansion of

concrete due to temperature change, structural settlement, surrounding loads caused by passing of

vehicles and hydrostatic pressure.
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ISO/TR 16475:2020(E)

These factors affect the repair material adhesion on the concrete substrate surface, the watertightness

and the elongation of the repair materials.
5 Expected performance for repair materials
5.1 General

Materials used for repairing water-leakage cracks prevent water leakage by maintaining an adequate

response performance to the environmental conditions. To this end, a thorough understanding of the

expected performance of the repair materials can assist in selecting the appropriate material. The

expected performance can be divided into the categories outlined in 5.2 and 5.3.
5.2 Expected performance for chemical conditions
5.2.1 Thermal stability

Under a high degree of temperature change, the concrete substrate is subject to direct or indirect

effects of dry-shrinkage, structural movement and joint movement of the concrete substrate. Repair

materials can seem to maintain a cohesive bond when installed in concrete substrate surface based on

the results of empirical data of standard testing. However, it is advised that a qualitative delamination

resistance property testing be conducted to conclusively ensure that the selected water leakage repair

material can maintain an integral structure while subject to a variety of degradation factors.

5.2.2 Chemical resistance

Concrete structures are constructed under various chemical environmental conditions. Waterproofing

membranes are often exposed to contact to water or soil in underground structures. In cases where

the concrete structures are located near industrial areas or seashores, corrosion caused by chemical

substances (e.g. acid, alkali, salt water or calcium hydroxide and carbon dioxide) can occur more

frequently. In addition, chemical corrosion decreases the performance of the injected repair materials

by hindering normal chemical reactions caused by mixing different admixtures.
5.3 Expected performance for physical (mechanical) conditions
5.3.1 Water (wash out) resistance

Water-leakage cracks are subject to intermittent or continuous hydrostatic pressure. For non-grout

injection type repair materials that require curing period (liquid/semiliquid state) and have low

concentration gradient, the material can be discharged or washed out of the crack due to water flow

before the material reaction can fully form a waterproof layer. For some types of materials, this can

lead to environmental pollution. For grout type and cementitious repair materials, long-term exposure

to water flow can also lead to material erosion, with some materials remaining whole inside the crack

longer than others.

Manufacturers and architects/engineers can be consulted to find out all the information pertaining to

the specific properties and limitations of the repair material when concerning the washout resistance

performance of the repair materials.
5.3.2 Adhesion on wet substrate surface

In most cases, repair materials are injected into water-leakage cracks while moisture is still present

at the interface of the crack surface. By conducting proper surface treatment prior to injection, elected

repair material can secure a sufficiently strong adhesive bond to surfaces with moisture. Necessary

information on the injection amount and speed is to be obtained from manufacturer instructions.

An evenly distributed application of the repair material can ensure a more durable and stable

waterproofing membrane structure within the water-leakage crack.
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ISO/TR 16475:2020(E)

Manufacturers and architects/engineers can be consulted to find out all the information pertaining

to the specific properties and limitations of the repair material when concerning the adhesion

performance on wet substrate surface of the repair materials.
5.3.3 Watertightness

Watertightness refers to the integral waterproofing performance of the repair material system

installed in the concrete structure. Under the parameters of this document, watertightness is defined

with the following criteria:
1) impermeability of the repair material to hydrostatic pressure;

2) the adhesive bond of the repair material to the concrete substrate surface to prevent ingress of

water through leakage paths formed in the interface of material adhesion failure; and

3) the cohesive bond of the repair material to prevent delamination or breakage due to structural

movement.

When repairing water-leakage cracks, repair materials with the correct performance properties

can satisfy the required watertight performance standard. The installation procedure is conducted

correctly in accordance to manufacturer instructions to ensure that the repair material can secure

a proper adhesion onto the wet concrete surface. Lastly, it is to select repair materials that will not

delaminate or permanently deform under hydrostatic pressure and repeated structural movement.

5.3.4 Response to the substrate movement

Water-leakage cracks or construction joints are subject to constant micro movements caused by drying

shrinkage and expansion due to changes in the capillary water amount, temperature, hydrostatic

pressure, structural settlement and various types of loads from surrounding sources. Repair material

membranes bonded onto the interface of the water-leakage crack surface are subject to strain which

can results in cohesive and/or adhesive failure. Regarding substrate movement resistance performance

of repair materials, it is important to ensure that the selected injected repair material has sufficient

elasticity and substrate movement response performance.

Manufacturers and architects/engineers can be consulted to find out all the information pertaining

to the specific properties and limitations of the repair material when concerning the performance

response to the substrate movement of the repair materials.
6 Grout materials for repair
6.1 General

Injection type grout repair materials are commonly used in today’s market for repair water-leakage

cracks. Among these, some of the most common types include acrylics grout, water-based cementitious

grout, hydrophilic epoxy resin grout, polyurethane foam grout, synthetic rubberized gel grout and

others. For most repair material products, details on the ingredient components, optimal mixture

ratios and empirical data on physical properties are available in manufacturer guidelines.

However, in construction sites there are numerous factors that can differ from manufacturer directions

for proper installation. The ambient condition and duration of storage, mixture time and degree of

different components, quality of workmanship and environmental conditions are all factors that

can influence the quality of the repair work. In cases where conditions outlined in the manufacturer

guidelines cannot be met, repair materials can be designed to satisfy certain basic requirements to

compensate for the possibilities of early failure and re-opening of cracks due to improper installation.

There have been numerous attempt
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