ISO 11528:2016

INTERNATIONAL ISO
STANDARD 11528
First edition
2016-08-01
Buildings and civil engineering
works — Sealants — Determination
of crazing and cracking following
exposure to artificial or natural
weathering
Bâtiments et ouvrages de génie civil — Mastics — Détermination du
tressaillage et du craquelage suite à une exposition au vieillissement
naturel ou artificiel
Reference number
ISO 11528:2016(E)
©
ISO 2016

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ISO 11528:2016(E)

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ISO 11528:2016(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus . 2
6 Observer . 2
7 Evaluation specimens . 2
7.1 General . 2
7.2 Specimen thickness . 2
7.3 Size of inspection surface. 2
7.4 Flatness of inspection surface . 2
7.5 Conditioning of evaluation specimens . 2
8 Procedure. 3
8.1 Viewing of evaluation specimens . 3
8.2 Assessment of test specimens prior to exposure . 3
8.3 Weathering . 3
8.4 Assessment of test specimens after exposure . 3
8.5 Photo documentation of evaluation specimens . 5
9 Test report . 6
Annex A (informative) Photographic documentation . 8
Annex B (informative) Preparation of the specimen for photography .14
Bibliography .18
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ISO 11528:2016(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
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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
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For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 59, Building and civil engineering works,
Subcommittee SC 8, Sealants.
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INTERNATIONAL STANDARD ISO 11528:2016(E)
Buildings and civil engineering works — Sealants —
Determination of crazing and cracking following exposure
to artificial or natural weathering
1 Scope
This International Standard specifies methods for the assessment of surface defects (crazing and
cracking) on sealants after exposure to artificial or natural weathering.
NOTE Sealants are weathered in the laboratory in order to simulate ageing processes occurring during
natural weathering. Generally, valid correlations between ageing during artificial and natural weathering cannot
be expected because of the large number of influencing factors. Certain relationships can only be expected if
the effect of the important parameters (spectral distribution of the irradiance in their photochemically relevant
range, temperature of the specimen, type of wetting, wetting cycle relative humidity) on the sealant is known.
However, unlike natural weathering, testing in the laboratory is carried out taking into consideration a limited
number of variables which can be controlled, and therefore, the results are more reproducible.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 291, Plastics — Standard atmospheres for conditioning and testing
ISO 3668, Paints and varnishes — Visual comparison of the colour of paints
ISO 6927, Buildings and civil engineering works — Sealants — Vocabulary
CIE Publication No.51, A Method for Assessing the Quality of Daylight Simulators for Colorimetry’ (CIE
051.2-1999 (including Supplement 1-1999)
3 Terms and definitions
For the purposes of this document, the definitions given in ISO 6927 apply.
4 Principle
This International Standard defines an evaluation scheme for designating the quantity and quality
of specific surface defects (cohesive cracks and crazes) occurring in sealants as a result of exposure
to outdoor or artificial weathering. The sealant test specimens are visually examined and rated for
crack density, crack width, and crack depth. The extent of damage in terms of crack width and crack
density is determined by visual evaluation and comparison with pictorial references provided in this
International Standard. The crack depth is visually assessed with reference to a rating scale.
Visual assessment is carried out under specified illumination and viewing conditions in artificial
daylight (D65). Findings are documented by digital photography.
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ISO 11528:2016(E)

5 Apparatus
5.1 Standardized lighting apparatus, in accordance with ISO 3668, which is illuminating the test
specimen surface with artificial daylight (D65) – 6 500 K.
The quality of simulation of daylight shall be assessed by the method described in CIE Publication No.
51. The spectral distribution of the illuminant shall be in category BC (CIELAB) or better. The level of
illumination at the specimen inspection position shall be between 2 000 lx and 4 000 lx.
5.2 Calliper gauge, with an accuracy of ±0,05 mm, for the measurement of deviation of specimen
surface flatness.
5.3 Microscope, with a magnification of 10×, for the assessment of surface defects.
6 Observer
Observers shall have normal colour vision and shall be selected carefully because a significant
proportion of people have defective colour vision. To avoid eye fatigue effects, pastel or complementary
colours shall not be viewed immediately after strong colours. The quality of visual judgements falls off
severely if the observer works continuously. Rest periods of several minutes, during which no specimen
inspection is attempted, shall therefore be taken frequently.
7 Evaluation specimens
7.1 General
Evaluation specimens are cured sealant samples with or without adjacent substrates (supports) that
have been exposed to either natural (outdoor) or artificial weathering. A minimum of two specimens
shall be evaluated for each sealant product and weathering condition.
7.2 Specimen thickness
The thickness of the evaluation specimen (cured sealant layer) shall be a minimum of 3 mm.
7.3 Size of inspection surface
The size of the specimen surface that is inspected for surface defects shall be at a minimum
10 mm × 20 mm and at a maximum 40 mm × 50 mm in size.
NOTE Standard-sized test specimens according to ISO 8339 are deemed as providing a suitable inspection
surface.
7.4 Flatness of inspection surface
The inspection surface of the evaluation specimens shall be nearly flat, i.e. the deviation of the
inspection surface from a perfect plane shall not exceed ±2 mm at any point across the inspection
surface. Deviation from the plane is measured by placing a straight-edge steel ruler across the specimen
and using a standard pointed depth gauge (calliper gauge, 5.2). The measured value shall be expressed
as concave (+) when the surface layer is facing towards the ruler and as convex (−) when the surface
layer is facing away from the ruler.
7.5 Conditioning of evaluation specimens
The evaluation specimens shall be conditioned at (23 ± 2) °C and (50 ± 10) % relative humidity (standard
atmosphere 23/50 class 2 according to ISO 291) for a minimum of 16 h prior to inspection.
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ISO 11528:2016(E)

8 Procedure
8.1 Viewing of evaluation specimens
View the evaluation specimens at a distance of 30 cm to 40 cm and an angle of 45° to 60° with
illumination at an angle of 90° or vice versa in a controlled lighting apparatus (5.1) under standardized
lighting conditions [conforming to CIE standard illuminant artificial daylight (D65) – 6500 K].
8.2 Assessment of test specimens prior to exposure
If evaluation specimens are not obtained from the field and therefore are available prior to exposure,
each specimen shall be inspected. Specimens with any significant application defects (bubbles,
deviations from planarity, etc.) shall be discarded.
8.3 Weathering
The evaluation specimens shall be exposed to natural (outdoor) or artificial weathering.
NOTE Weathering can be carried out with or without simultaneous or sequential cyclic movement. For a
discussion of different weathering methods see, for instance, ISO 11617 or the RILEM Technical Recommendations.
[2][3][4]
8.4 Assessment of test specimens after exposure
After exposure to natural (outdoor) or artificial weathering, the evaluation specimens are inspected
visually under controlled lighting conditions (see 8.1). Inspection of the evaluation specimens may
occur in their non-extended state or, preferably, in an extended state. The extension amplitude applied
during inspection of the evaluation specimens shall be reported in the test report (extension amplitude
of non-extended specimens: 0 %).
The specimens shall be examined for evidence of loss of adhesion and cohesion or any surface changes
(cracking, crazing, chalking, etc.) of the sealant beads. Certain types of degradation that are only visible
at the back surface may occur. Report any relevant observation, such as splitting of the sealant surface,
depolymerization (reversion) of the bulk sealant, etc.
Determine the rating for quantity, width, and depth of cohesive cracks over the inspection area
according to Table 1, Table 2, and Table 3, respectively. Assess the quantity of cohesive cracks by
reference to Table 1 and by using, as an example, Figure 1 a) and Figure 1 b), depending on the type
of cracking. The degree of degradation (crack width, crack density, and crack depth) can vary over the
specimen surface. In such cases, the determination of the crack width, crack density, and crack depth
shall be made at several locations on the specimen surface and the minimum and maximum value shall
be reported.
NOTE 1 Figure 1 a) shows cracking without preferential direction and Figure 1 b) shows cracking in one
preferential direction. Other forms of cracking occur, but the p
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