ASTM C1521-19(2020)
(Practice)Standard Practice for Evaluating Adhesion of Installed Weatherproofing Sealant Joints
Standard Practice for Evaluating Adhesion of Installed Weatherproofing Sealant Joints
SIGNIFICANCE AND USE
4.1 Many parameters contribute to the overall performance of a sealant application. Some of the most significant parameters are sealant bead size and configuration, joint movement, quality of workmanship, the quality of the adhesive bond, and the quality of the sealant material.
4.2 A sealant usually fails to perform as a weatherseal when it experiences cohesive or adhesive failure.
4.3 If a sealant bead fails, an evaluation of the total joint movement may be needed to determine if the joint sealant was strained beyond its intended design, or if the sealant failed within the design parameters.
4.4 If a sealant bead fails adhesively, there is no straightforward procedure for determining the cause. The adhesive failure may be due to workmanship, the specific surface preparation used, the specific sealant used, poor “installed” joint design, poor bond chemistry and other causes.
4.5 Because of the complex nature of the performance of a sealant bead, an understanding of the quality of the adhesive bond is instrumental in any evaluation of sealant performance. It is critical that the evaluation procedures used truly evaluate the quality of the adhesive bond and do not simply take advantage of the tear resistance of the sealant.
4.6 This method does not evaluate the performance of a sealant bead as a weatherseal. It only evaluates the characteristics of the adhesive bond relative to the cohesive strength of the sealant in a particular installation. Since any failures that result from use of these procedures are intentionally induced, they do not necessarily mean that the sealant bead will not perform as a weatherseal.
4.7 The results of these methods are most useful in identifying sealant beads with poor adhesion. The continuous inspection procedure is also useful in the identification of places of poor joint configuration. Obvious cohesive failures are also identified. The results of these methods can be used to assess the likely performance of the seal...
SCOPE
1.1 This practice describes destructive and non-destructive procedures.
1.2 The destructive procedure stresses the sealant in such a way as to cause either cohesive or adhesive failure of the sealant or cohesive failure of the substrate where deficient substrate conditions exist. The objective is to characterize the adhesive/cohesive performance of the sealant on the specific substrate by applying a strain that correlates to the strain that the sealant bead may experience when subjected to its maximum published movement capability, when known; or a reasonable strain when the movement capability is unknown. It is possible that the strain applied to the sealant bead may result in no failure of the sealant or the substrate, failure of a deficient substrate before effecting a failure in the sealant, or a failure of the sealant.
Note 1: The destructive procedure requires immediate repair of the sealant bead. Appropriate materials and equipment should be available for this purpose.
Note 2: Sealant formulations may fail in cohesion or adhesion when properly installed, and evaluated by this method. The sealant manufacturer should be consulted to determine the appropriate guidelines for using this method.
1.3 The non-destructive procedure places strain on the sealant and a stress on the adhesive bond. Though termed non-destructive, this procedure may result in an adhesive failure of a deficient sealant bead, but should not cause a cohesive failure in the sealant. The results of this procedure should be either adhesive failure or no failure.
Note 3: The non-destructive procedure may require immediate repair of the sealant bead, if sealant failure is experienced. Appropriate materials and equipment should be available for this purpose.
1.4 The non-destructive procedure can be used for continuous inspection of 100 % of the sealant bead(s), or for any areas where deficient conditions, which are inconsistent with the pr...
General Information
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Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C1521 −19 (Reapproved 2020)
Standard Practice for
Evaluating Adhesion of Installed Weatherproofing Sealant
Joints
This standard is issued under the fixed designation C1521; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.5 The committee with jurisdiction over this practice is not
aware of any comparable practices published by other organi-
1.1 This practice describes destructive and non-destructive
zations or committees.
procedures.
1.6 The values stated in inch-pound units are to be regarded
1.2 The destructive procedure stresses the sealant in such a
as standard. The values given in parentheses are mathematical
way as to cause either cohesive or adhesive failure of the
conversions to SI units that are provided for information only
sealant or cohesive failure of the substrate where deficient
and are not considered standard.
substrate conditions exist. The objective is to characterize the
1.7 This standard does not purport to address all of the
adhesive/cohesive performance of the sealant on the specific
safety concerns, if any, associated with its use. It is the
substrate by applying a strain that correlates to the strain that
responsibility of the user of this standard to establish appro-
the sealant bead may experience when subjected to its maxi-
priate safety, health, and environmental practices and deter-
mum published movement capability, when known; or a
mine the applicability of regulatory limitations prior to use.
reasonablestrainwhenthemovementcapabilityisunknown.It
1.8 This international standard was developed in accor-
is possible that the strain applied to the sealant bead may result
dance with internationally recognized principles on standard-
innofailureofthesealantorthesubstrate,failureofadeficient
ization established in the Decision on Principles for the
substrate before effecting a failure in the sealant, or a failure of
Development of International Standards, Guides and Recom-
the sealant.
NOTE 1—The destructive procedure requires immediate repair of the mendations issued by the World Trade Organization Technical
sealant bead.Appropriate materials and equipment should be available for
Barriers to Trade (TBT) Committee.
this purpose.
NOTE 2—Sealant formulations may fail in cohesion or adhesion when
2. Referenced Documents
properlyinstalled,andevaluatedbythismethod.Thesealantmanufacturer
2.1 ASTM Standards:
should be consulted to determine the appropriate guidelines for using this
method.
C717 Terminology of Building Seals and Sealants
C794 TestMethodforAdhesion-in-PeelofElastomericJoint
1.3 The non-destructive procedure places strain on the
Sealants
sealant and a stress on the adhesive bond. Though termed
C1193 Guide for Use of Joint Sealants
non-destructive, this procedure may result in an adhesive
failure of a deficient sealant bead, but should not cause a
3. Terminology
cohesive failure in the sealant. The results of this procedure
3.1 Definitions—For definitions of terms used in this rec-
should be either adhesive failure or no failure.
ommended procedure, see Terminology C717.
NOTE 3—The non-destructive procedure may require immediate repair
of the sealant bead, if sealant failure is experienced.Appropriate materials
3.2 Definitions of Terms Specific to This Standard:
and equipment should be available for this purpose.
3.2.1 flap, n—the term “flap” as used in this specification
1.4 The non-destructive procedure can be used for continu-
refers to a portion of an installed sealant bead that has been
ous inspection of 100 % of the sealant bead(s), or for any areas
purposelycutalongonesubstratebondlineandacrossthebead
where deficient conditions, which are inconsistent with the
at two locations resulting in a portion of bead adhered along
practices of Guide C1193, are suspected.
one substrate bond line.
3.2.2 tail, n—the term “tail” as used in this specification
refers to a portion of an installed sealant bead that has been
This practice is under the jurisdiction of ASTM Committee C24 on Building
Seals and Sealants and is the direct responsibility of Subcommittee C24.30 on
Adhesion. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2020. Published June 2020. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2002. Last previous edition approved in 2019 as C1521 –19. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/C1521-19R20. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1521 − 19 (2020)
purposely cut along both substrate bond lines and across the 5.3 Provide materials for recording data.These may include
bead at one location resulting in a portion of bead unadhered to masking tape, marking pen, note books, shop or architectural
the substrates but adhered to the remainder of the sealant bead. drawings, a camera or video recorder, or both.
4. Significance and Use
6. Summary of Methods
4.1 Many parameters contribute to the overall performance
6.1 Non-destructive Spot Method—This method makes use
of a sealant application. Some of the most significant param-
of a blunt dowel shaped tool to impart pressure against the
eters are sealant bead size and configuration, joint movement,
surface of the sealant bead. Firm pressure is applied to the
quality of workmanship, the quality of the adhesive bond, and
surface of the sealant in the center of the bead and near the
the quality of the sealant material.
bond line. This method evaluates a discrete area of the sealant
4.2 Asealant usually fails to perform as a weatherseal when
bead and is repeated numerous times to provide an evaluation
it experiences cohesive or adhesive failure.
of a given length of sealant bead.
4.3 If a sealant bead fails, an evaluation of the total joint
6.2 Non-destructive Continuous Method—This method
movement may be needed to determine if the joint sealant was
makes use of a wheel to impart pressure against the surface of
strained beyond its intended design, or if the sealant failed
the sealant bead. The wheel is rolled continuously along the
within the design parameters.
center of the sealant bead to provide 100 % inspection of a
4.4 If a sealant bead fails adhesively, there is no straight-
given length of sealant bead.
forward procedure for determining the cause. The adhesive
6.3 All Methods—Data is collected continuously for all
failure may be due to workmanship, the specific surface
methods. Precise description of location and type of all
preparation used, the specific sealant used, poor “installed”
anomalies is recorded by a method appropriate for the given
joint design, poor bond chemistry and other causes.
evaluation. See Appendix X1.
4.5 Because of the complex nature of the performance of a
6.4 Destructive Method—This method is performed by cut-
sealant bead, an understanding of the quality of the adhesive
ting through the sealant bead to provide either a “tail” or a
bond is instrumental in any evaluation of sealant performance.
“flap” of sealant that can be pulled by hand, to stress the bond
It is critical that the evaluation procedures used truly evaluate
line of the sealant. The width and location of the sealant bead
the quality of the adhesive bond and do not simply take
will determine how and to what degree the hand pull method
advantage of the tear resistance of the sealant.
can be performed. This method uses described techniques to
4.6 This method does not evaluate the performance of a
cause an adhesive failure from the substrate.
sealant bead as a weatherseal. It only evaluates the character-
6.4.1 Water Immersion—This method makes use of a vessel
istics of the adhesive bond relative to the cohesive strength of
filled with water to expose a sealant bead to water before
the sealant in a particular installation. Since any failures that
performing the procedures described in 7.1-7.4. This method
result from use of these procedures are intentionally induced,
can also be performed in the event that project specific
they do not necessarily mean that the sealant bead will not
substrates are not able to be evaluated in the laboratory for
perform as a weatherseal.
surface preparation recommendations based on testing in
accordance with adhesion methods such as Test Method C794.
4.7 The results of these methods are most useful in identi-
It is advisable to perform a field adhesion evaluation both dry
fyingsealantbeadswithpooradhesion.Thecontinuousinspec-
and wet.
tion procedure is also useful in the identification of places of
NOTE 4—Narrow joints (less than ⁄16 in. or 8 mm wide) do not lend
poor joint configuration. Obvious cohesive failures are also
themselvestodestructivefieldadhesionprocedures.Usually,somekindof
identified. The results of these methods can be used to assess
“tail” can be provided to perform an adhesion pull. However, these
the likely performance of the sealant bead and to compare the
procedures, when used on narrow joints, tend to evaluate the cohesive
adhesion of different substrate preparations and sealant mate-
property of the sealant more than the adhesive property.
NOTE 5—Joints that are less than ⁄8 in. or 16 mm wide or that are more
rials.
than ⁄2 in. (13 mm) deep do not lend themselves to a “flap” style adhesion
4.8 The non-destructive methods are most effective while
pull. The “tail” style adhesion pull should be performed on these joints.
the sealant is in a state of extension due to mild or low
temperatures. They are least effective during high temperature
7. Procedures
when the sealant is in a compressed condition.
7.1 Non-destructive Procedure:
5. Testing Equipment
7.1.1 Select a probing tool that is at least ⁄8 in. (3 mm)
narrower than the width of the sealant joint to be evaluated.
5.1 Field Equipment—The following equipment is required
1 Fig. 1 provides example dimensions for a probing tool.
to perform this practice: rule with ⁄32 in. divisions (mm),
probingtool,razorknife,knifeorothercuttinginstrumentwith
NOTE 6—The probing tool should be blunt without sharp edges and
a pointed 2 in. (50 mm) minimum length blade, sealable shaped in such a way that it will not puncture the sealant bead.
sample bags, repair sealant compatible with existing sealant,
7.1.2 Technique 1—Using the probing tool, depress the
tools for installing sealant, butyl tape, water.
center of the sealant bead to create an elongation strain on the
5.2 Field Equipment, Non-destructive Continuous sealant bead. Record the depth of the depression as a percent-
Method—Awheel roller such as a screen roller or a backer rod age of the width of the bead. A common percentage used to
insertion roller or a pressure controlled roller. create reasonable strain and reveal poor adhesion is 50 %. The
C1521 − 19 (2020)
generally helpful to remove a portion of the sealant and backer
material for inspection. Sometimes, a more thorough examina-
tion of the anomaly location will be required. The destructive
procedure described in 7.3 can be used.
7.3 Destructive Procedure:
7.3.1 The “Tail” Procedure consists of cutting through the
sealant, 6 in. (150 mm) along the bond line at both substrates.
Cut across the sealant bead to release one end of the “tail” that
is formed (see Fig. 2). Insure that the sealant is cut at the
substrate and that the sealant bead is free of nicks or jagged
edges.
7.3.2 Method A:
7.3.2.1 Mark the cut portion of the sealant 1 in. (25 mm)
from the adhesive bond.
7.3.2.2 Grasp the sealant “tail” at the mark 1 in. (25 mm)
from the adhesive bond.
7.3.2.3 Pull tail at an angle of 90° to the substrate to
effectively extend the 1-in. mark a distance equivalent to the
FIG. 1 Probing Tool
sealant manufacturer’s published movement capability of the
sealant.
appropriate percentage varies with each sealant joint and is
approximately proportional to the expected joint movement.
The percentage can be correlated with destructive procedure
results.
7.1.3 Technique 2—Locating the probing tool adjacent to
the sealant/substrate bond line, depress the sealant bead to the
extent that (visually) it appears the sealant is about to fail
cohesively.Thesealantbeadshouldbedepressedinsuchaway
that the probing tool does not contact or scrape against the
substrate, nor slide toward the center of the joint. This
techniquewilleffectapeel-typestrainonthesealantjoint.This
technique will produce shear forces close to the bond line and
therefore the results should be prudently interpreted.
7.2 Non-destructive Continuous Inspection Procedure:
7.2.1 Place masking tape on the exposed surface of the
substrate adjacent to the sealant to be inspected. Using a roller
of such thickness as to be equal to or less than half of the width
of the joint, apply pressure to the sealant through the roller to
develop a depression in the sealant joint that represents
approximately 50 % deflection of the sealant. Advance the
roller along the centerline of the length of the joint, using
uniform pressure. Observe the condition of the sealant for
conditions, such as deflection of the sealant that is greater than
or less than expected, adhesive failure, cohesive failure or
mechanical damage to the sealant, and mark the location of
these conditions on the masking tape. It is helpful to use
characteristic marks such as “A” for adhesion loss, “H” where
the sealant appears hard, “S” where the sealant appears soft,
“C” where a cohesive failure exists, for example, when
marking the masking tape. Where extended length of adhesive
failure occurs, the masking tape can be marked to indicate the
ends of the adhesive failures. The tape can also contain
markings that identify the location and side of the joint at
which it is located. Upon completion of depressing the sealant
with the roller, documentation of the locations and types of
conditions can be performed.
7.2.2 Determining the Causes of the Anomalies—Each
anomaly can be inspected for obvious causes. However, it is FIG. 2 Tail Procedure
C1521 − 19 (2020)
7.3.2.4 Record the type of failure that occurred and the
distance of the mark from the adhesive bond when failure
occurred, or the distance recommended by manufacturer with-
out causing failure.
7.3.3 Method B:
...
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