Designation: C 1184 – 05

Standard Specification for

Structural Silicone Sealants1
This standard is issued under the fixed designation C 1184; 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 (e) indicates an editorial change since the last revision or reapproval.

1. Scope C 794 Test Method for Adhesion-in-Peel of Elastomeric

1.1 This specification describes the properties of cold liquid Joint Sealants
applied, single-component or multicomponent, chemically cur- C 1087 Test Method for Determining Compatibility of
ing elastomeric structural silicone sealants herein referred to as Liquid-Applied Sealants with Accessories Used in Struc-
the sealant. These sealants are intended to structurally adhere tural Glazing Systems
components of structural sealant glazing systems. C 1135 Test Method for Determining Tensile Adhesion
1.2 Only those properties for which there are industry- Properties of Structural Sealants
agreed-upon minimum acceptable requirements, as determined C 1401 Guide for Structural Sealant Glazing
by available ASTM test methods, are described in this speci- C 1442 Practice for Conducting Tests on Sealants Using
fication. Additional properties may be added as ASTM test Artificial Weathering Apparatus
methods for those properties become available. G 151 Practice for Exposing Nonmetallic Materials in Ac-
1.3 The values stated in metric (SI) units are to be regarded celerated Test Devices That Use Laboratory Light Sources
as the standard. The values in parentheses are for information G 154 Practice for Operating Fluorescent Light Apparatus
only. for UV Exposure of Nonmetallic Materials
1.4 Committee C24, with jurisdiction over this specifica- G 155 Practice for Operating Xenon Arc Light Apparatus
tion, is aware of two comparable standards by other organiza- for Exposure of Nonmetallic Materials
tions: ETAG No. 002 and the Chinese national standard 2.2 European Organization for Technical Approvals Docu-
GB16776. ment:3
ETAG No. 002 Guideline for European Technical Approval
2. Referenced Documents for Structural Sealant Glazing Systems
2.1 ASTM Standards: 2 2.3 Chinese National Standard:4
C 603 Test Method for Extrusion Rate and Application Life GB 16776–1997 Structural Silicone Sealants for Building
of Elastomeric Sealants
3. Terminology
C 639 Test Method for Rheological (Flow) Properties of
Elastomeric Sealants 3.1 Definitions—Refer to Terminology C 717 for definitions
C 661 Test Method for Indentation Hardness of of the following terms used in this specification: adhesive
Elastomeric-Type Sealants by Means of a Durometer failure, chemically curing sealant, cohesive failure, compatibil-
C 679 Test Method for Tack-Free Time of Elastomeric ity, cure, elastomeric, glazing, hardness, non-sag sealant,
Sealants primer, sealant, shelf life, silicone sealant, structural sealant,
C 717 Terminology of Building Seals and Sealants substrate, and tooling.
C 792 Test Method for Effects of Heat Aging on Weight
4. Significance and Use
Loss, Cracking, and Chalking of Elastomeric Sealants
4.1 Not all sealants meeting this specification should be
presumed to be suitable for all applications and all substrates.
1
This specification is under the jurisdiction of ASTM Committee C24 on This specification assists in selecting sealants that meet certain
Building Seals and Sealants and is the direct responsibility of Subcommittee C24.10 minimum standards of performance.
on Specifications, Guides and Practices. 4.2 Although this specification qualifies a sealant for use, it
Current edition approved Sept. 1, 2005. Published October 2005. Originally
approved in 1991. Last previous edition approved in 2000 as C 1184 – 00ae1.
does not address the adhesion capability of the sealant for a
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
3
Standards volume information, refer to the standard’s Document Summary page on Available from www.eota.be
4
the ASTM website. Published May 15, 2005, Implemented August 1, 1997; www.nstn.org

Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.

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 C 1184 – 05
specific substrate nor the compatibility of the sealant with the specification shall be performed wit the primer. When a primer
materials it contacts. Adhesion and compatibility characteris- is not required by the sealant manufacturer, all tests performed
tics required for specific substrates or finishes can be deter- in accordance with this specification shall be performed
mined by Test Method C 794 for adhesion and Test Method without a primer.
C 1087 for compatibility. NOTE 1—The proper use of primers is described in Guide C 1401.
4.3 To properly specify a sealant for the intended use when
using this specification, it is essential that the applicable type 7.3 The standard substrate for this specification is clear,
and use be included. uncoated float glass.
7.4 Standard conditions referred to in this specification are a
5. Classification of Sealants temperature of 23 6 2°C (73.4 6 3.6°F) and 506 5 % relative
5.1 A sealant qualifying under this specification shall be humidity.
classified as to type and use as given in 4.1.1-4.1.4.
5.1.1 Type S—Single-component sealant. 8. Test Methods
5.1.2 Type M—Multicomponent sealant. 8.1 Rheological Properties—Test Method C 639, using test
5.1.3 Use G—A sealant that meets the requirements of this procedures for Type II and IV sealants.
specification when tested on a clear, uncoated float glass 8.2 Extrudability—Test Method C 603.
substrate. 8.3 Hardness—Test Method C 661, using a Type A-2
5.1.4 Use O—A sealant that meets the requirements of this durometer.
specification when tested on a substrate other than a clear, 8.4 Heat Aging—Test Method C 792, using a temperature of
uncoated float glass substrate (for example, Use O—Granite). 88 6 5°C (190 6 10°F).
8.5 Tack-Free Time—Test Method C 679.
6. Materials and Manufacture 8.6 Tensile Adhesion—Test Method C 1135, using a rate of
6.1 Furnish single-component sealants as a homogeneous pull of 12.7 mm (1⁄2 in.)/min. Determine the average ultimate
mixture of a consistency suitable for application and within the tensile value for each group of five specimens prepared as
manufacturer’s stated shelf life. Apply the sealant in accor- described in 8.6.1 and 8.6.2.
dance with the written recommendations of the sealant manu- 8.6.1 Prepare, in accordance with Test Method C 1135, a
facturer. The cured sealant shall be an elastomeric solid. total of 25 specimens for testing, except that the distance
6.2 Furnish multicomponent sealants in two or more com- between substrates will be 9.5 mm (3⁄8 in.).
ponents. Mix and apply the sealant in accordance with the 8.6.2 Cure all specimens for 21 days at standard conditions.
written recommendations of the sealant manufacturer. The Condition and test the specimens as described in 8.6.2.1-
cured sealant shall be an elastomeric solid. 8.6.2.5.
6.3 Furnish primer of the type required by, and apply in 8.6.2.1 Test five specimens at standard conditions after the
accordance with, the written recommendations of the sealant initial curing period.
manufacturer. 8.6.2.2 Condition five specimens for 1 h at 88 6 5°C (190
6 10°F) in a forced air oven. Test the specimens at 88 6 5°C
7. Requirements
(190 6 10°F).
7.1 The physical, mechanical, and performance properties 8.6.2.3 Condition five specimens for 1 h at −29 6 2°C (−20
of the sealant shall conform to the requirements described in 6 4°F). Test the specimens at −296 2°C (−20 6 4°F).
Table 1. 8.6.2.4 Immerse five specimens in deionized or distilled
7.2 When a primer (see Note 1) is required by the sealant water at standard temperature for seven days. Test the speci-
manufacturer, all tests performed in accordance with this mens at standard conditions within 10 min after their removal
from the water.
TABLE 1 Requirements for Physical, Mechanical and 8.6.2.5 Expose five specimens with the bond surface facing
Performance Qualities of the Sealant the light source to either of the exposure conditions specified
Property Requirement Test Method below in apparatus that conforms to the requirements defined
Rheologic, max C 639 in Practice C 1442. Because of differences in spectral power
Vertical 4.8 mm (3⁄16 in.) distribution of the exposure sources (consult G 154 and G 155)
Horizontal no deformation
Extrudability, max 10 s C 603 and differences in test parameters, test results may differ
Hardness, Shore A 20-60 C 661 between the two types of tests. Choice of type of exposure shall
Heat aging be by mutual agreement between the interested parties.
Weight loss, max 10 %
Cracking none NOTE 2—Refer to Practice G 151 for full cautionary guidance regarding
Chalking none
laboratory weathering of nonmetallic materials.
Tack-free time, max no transfer in 3 h C 679
Tensile value, min C 1135 (a)Fluorescent UV/Condensation Apparatus—Operate the
Standard conditions: 345 kPa (50 psi)
88°C (190°F) 345 kPa (50 psi) device in accordance with the procedure in Practice C 1442,
−29°C (−20°F) 345 kPa (50 psi) Section 7.3 and expose the specimens for a minimum of 5,000
Water immersion 345 kPa (50 psi) h.
5000 h weathering 345 kPa (50 psi) 8.6.2.5
Shelf life, min 6 months 9.1 (b)Xenon Arc Weathering Device—Operate the device in
accordance with the procedure in C 1442, Section 7.2. Expose

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 C 1184 – 05
specimens for a minimum of 5,000 h at the irradiance level of poor performance in the application of interest.
0.51 W/(m2· nm) at 340 nm. The radiant exposure is 9180
kJ/(m2· nm) at 340 nm. To determine the exposure time 9. Shelf Life
required to obtain the same radiant exposure at other irradiance 9.1 If it is desired to test shelf life of a structural sealant,
levels specified in Practice C 1442, see Annex A1 in Practice then the test methods listed in Section 8 should be performed
C 1442. on sealant that has been stored to within 30 days of the
NOTE 3—The exposure duration shall be of sufficient length to produce manufacturer’s stated shelf life. All of the requirements of
a detectable change of the property evaluated for a material known to give Table 1 should be met.

APPENDIX

(Nonmandatory Information)

X1. STRUCTURAL SILICONE SEALANT MODULUS OF ELASTICITY

X1.1 General X1.1.5 The modulus of a sealant may be a function (essen-

X1.1.1 The purpose of this appendix is to describe modulus tially linear) of temperature. It should be verified that the
considerations for a structural silicone sealant that is intended modulus will fall within the minimum and maximum criteria
for a range of applications. Structural silicone sealants should over the anticipated service temperature range.
be designed for both strength and flexibility for specific X1.1.6 To adequately evaluate a sealant for a specific
applications; this implies that the sealant’s modulus of elastic- application, a stress/strain plot should be developed for the
ity should fall between a maximum and minimum value for a specific project conditions utilizing Test Method C 1135. When
specific application. developing the stress/strain plot, the test conditions (such as
X1.1.2 The modulus of elasticity of a material describes its sealant joint configuration or environmental conditioning)
elongation response to an applied stress, and therefore is a should be modified to correlate with the conditions specified or
measure of its flexibility, stiffness, or hardness. The term predicted for the specific specification. The application-specific
“modulus” used in this appendix refers to a sealant’s secant stress/strain plots (developed using the average values for each
modulus of elasticity; see Terminology C 717. Note that the set of test assemblies as described in Test Method C 1135), in
units of modulus and stress can be the same (such as pounds combination with the design criteria for the application, can be
per square inch), but they represent different technical con- evaluated to determine if the proposed sealant is appropriate
cepts. Because the modulus of a sealant is not constant, it is for the application.
customary in the sealant industry to state both the modulus and X1.2 Minimum Modulus
the strain at which it was measured (for example, 99 kPa at X1.2.1 The minimum acceptable structural sealant modulus
12.5 % strain). (softest, or highest acceptable flexibility) is based on the
X1.1.3 Structural silicone sealants are used to structurally premise that the sealant must be sufficiently stiff to retain the
attach glass and other materials to a framing system; to transfer panel without excessive deflection. The limiting case is when
loads applied to the glazing material to the framing system; and the sealant depth is stressed by negative (outward acting) wind
to accommodate anticipated movement between the glazed or other lateral loads up to its design load; even at that stress it
materials and the supporting framework. When selecting a must not elongate beyond the practical limit of the design
structural sealant for a specific application, the design profes- geometry (such as the setting blocks supporting the weight of
sional must select a sealant that has the necessary strength to the panel).
resist applied loads, but also has enough flexibility to accom-
modate differential movement. X1.3 Maximum Modulus
X1.1.4 Currently, structural silicone sealants are manufac- X1.3.1 The maximum acceptable modulus (hardest, or least
tured to have performance properties which allow a particular acceptable flexibility) is dictated by the requirement that the
material to be used in a wide variety of applications. If a structural sealant joint must have sufficient flexibility to re-
particular structural silicone sealant is to be used in a specific spond to the wind strain or differential thermal movement
application, it must have a modulus which is also acceptable between the panel and the supporting framework, without
for that application. being stressed in shear in excess of the design parameters.

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 C 1184 – 05

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