Information on the most widely used ASTM standards within the materials testing industry
ISO 8339, ISO 8440, ASTM C1135, ISO 7389
UnitedTest supplies ISO 8339 compliant tensile test fixture for building construction sealants. Standard sealant joint specimen grips for UTM, test elongation at break & secant modulus, lab certified, custom substrate holders available. UnitedTest engineers its ISO 8339 fixtures to hold the two substrate pieces in precise parallel alignment, accommodate the standardized 12 mm × 12 mm anti-adherent spacers, and maintain a fixed adhesion area throughout the 5.5 mm/min extension pull.
ISO 8339 Building construction - Sealants - Determination of tensile properties (Extension to break)
ASTM C1135 Standard Test Method for Determining Tensile Adhesion Properties of Structural Sealants
General introduction
ISO 8339 Sealant Tensile Test Fixture | Building Construction Joint Sealant Tensile Grips Manufacturer – UnitedTest
ISO 8339 Building Construction Sealants Tensile Test Fixture, engineered and manufactured by UnitedTest, fully complies with the latest valid international standard ISO 8339:2005 Building construction — Jointing products — Sealants — Determination of tensile properties (Extension to break). This specialized tensile grip set is designed exclusively for universal testing machines (UTM) to conduct tensile failure tests on construction joint sealants, silicone sealants, polyurethane sealants, acrylic building mastics, and facade caulking materials.
As a professional fixture manufacturer with 10+ years of material testing hardware experience, UnitedTest’s ISO 8339 sealant tensile fixture meets all dimensional, clamping and loading requirements specified in ISO 8339:2005, supporting parallel-substrate sealant joint specimens as defined in the standard test principle. It is also compatible with matching regional standards BS EN ISO 8339, UNI EN ISO 8339 and domestic equivalent GB/T 13477.8-2017 for global lab certification testing.
What Is ISO 8339 and Why Does the Fixture Matter?
ISO 8339:2005 "Building construction — Sealants — Determination of tensile properties (extension to break)" specifies the method for evaluating the tensile behavior of joint sealants used in building construction. The test measures secant modulus and elongation at break by adhering the sealant to two parallel substrates and stretching the assembly to rupture while recording a force–extension diagram.
The ISO 8339 test fixture is the critical interface between the sealant specimen and the universal testing machine. A poorly designed fixture introduces misalignment, uneven stress distribution, and inconsistent substrate bonding — all of which invalidate the force/extension curve. UnitedTest engineers its ISO 8339 fixtures to hold the two substrate pieces in precise parallel alignment, accommodate the standardized 12 mm × 12 mm anti-adherent spacers, and maintain a fixed adhesion area throughout the 5.5 mm/min extension pull.

Key Features
Upper fixed clamping jaw: Mounted to UTM moving crosshead, precision self-centering design
Lower stationary clamping jaw: Attached to UTM base frame, anti-slip locking bolts
Standard substrate specimen holders (match ISO 13640):
Anodized aluminum substrate blocks (default supply)
Optional glass / cement mortar substrate inserts for custom test requirements
Parallel alignment calibration shims: Ensure zero offset between upper & lower substrates to avoid specimen side load
Quick-release locking screws: Fast specimen loading/unloading to boost lab test throughput
Standard adapter connector: Universal fit for all UnitedTest WDW series computerized universal tensile testers; adapters for third-party UTM brands available on request
ISO 8339 Building construction - Sealants - Determination of tensile properties (Extension to break)
ASTM C1135 Standard Test Method for Determining Tensile Adhesion Properties of Structural Sealants
ISO 8340 Building construction - Sealants - Determination of tensile properties at maintained extension
ISO 7389:2004 Building construction - Jointing products - Determination of elastic recovery of sealants
GB/T 13477.8 Test method for building sealants—Part 8:Determination of tensile properties
100% ISO 8339:2005 Compliance: All structural dimensions, clamping geometry and specimen positioning strictly follow ISO standard clauses; test data meets third-party laboratory audit requirements for construction material certification.
Zero Torque Parallel Clamping: Unique double alignment structure eliminates uneven lateral force, solving common industry issues of premature sealant edge tearing and inconsistent test repeatability.
Modular & Interchangeable Design: Substrate inserts, crosshead adapters and calibration shims are replaceable; one fixture fits multiple sealant specimen types without purchasing separate grips.
Lab Durability & Low Maintenance: Anti-rust steel construction, wear-resistant clamping contact surfaces, no frequent part replacement for daily high-volume QC testing.
UnitedTest Full Technical Support: Free fixture installation guidance, calibration tutorial videos, and standard ISO 8339 test procedure documentation included with every order; global after-sales service for testing machine labs, sealant manufacturers, construction material R&D institutes.
Cost-Effective Customization: We offer custom substrate sizes, special alloy holders and customized UTM adapters for unique factory or third-party testing center demands.
ISO 8339 specifies testing sealant sandwiched between two identical, parallel rigid substrate blocks (aluminum, glass, mortar per ISO 13640 substrates) to measure two critical sealant performance metrics:
Elongation at break (maximum stretch ratio before sealant rupture)
Secant modulus at specified extension (stiffness index for construction joint design)
UnitedTest’s dedicated tensile fixture firmly clamps the two substrate plates of the sealant specimen vertically aligned, eliminates bending torque during tensile extension, and maintains a constant 5–6 mm/min test pulling speed required by ISO 8339 to capture accurate force-strain curves for sealant quality reports.
UnitedTest ISO 8339 tensile test fixture is widely adopted by global customers including:
Construction sealant manufacturers (silicone, PU, MS polymer, acrylic facade caulking R&D & QC labs)
Third-party construction material testing laboratories for ISO standard certification
Architectural engineering institutes for joint expansion compatibility research
Building material quality supervision authorities for incoming sealant batch inspection
Window & curtain wall factories evaluating weather-resistant joint mastics
ISO 8339 test fixture, building construction sealant tensile test, ISO 8339 extension to break fixture, UnitedTest sealant grip, EN ISO 8339:2005 testing apparatus, sealant tensile properties test equipment, 12 mm spacer sealant fixture, construction sealant universal testing machine. ISO 8339 tensile test fixture, ISO 8339 sealant grips, building construction sealant tensile fixture, ISO 8339 specimen holder, sealant tensile test jig, ISO 8339:2005 tensile fixture for UTM, construction joint sealant elongation test grip, silicone sealant tensile test fixture ISO standard, BS EN ISO 8339 testing fixture, sealant secant modulus test jig, UnitedTest tensile fixture manufacturer, universal testing machine sealant grips
Main specification:
| Substrate materials | Mortar, anodized aluminium, or glass (same material for both pieces) |
| Spacer cross-section | 12 mm × 12 mm, anti-adherent surface |
| Adaptor type | M10, M14, or custom thread to match UTM |
| Extension rate | 5.5 ± 0.7 mm/min |
| Test temperatures | 23 ± 2 °C and −20 ± 2 °C |
| Specimens per condition | 3 |
| Conditioning – Method A | 28 days at 23 ± 2 °C, 50 ± 5 % RH |
| Conditioning – Method B | Method A + 3 thermal/water cycles (70 ± 2 °C oven, distilled water at 23 ± 2 °C) |
| Measured outputs | Secant modulus (σ = F/s), elongation at break %, failure mode (adhesive/cohesive) |
Material & Finish | Fixture body: high-strength aircraft-grade aluminium alloy or heat-treated steel. Surface treatment: black anodized or black oxide finish for corrosion resistance in both ambient and −20 °C cold-chamber environments. Anti-adherent spacer contacts: precision-machined to keep the 12 mm × 12 mm spacer fixed in place during conditioning. |
Standard
ISO 8339 Building construction — Sealants — Determination of tensile properties (Extension to break)
ISO 8339 defines a laboratory tensile test method to measure full tensile mechanical performance of construction joint sealants by stretching bonded specimens until complete rupture. It quantifies secant modulus and elongation-at-break, which are core material parameters to evaluate elastic deformability and adhesion/cohesion of sealants under tension. It focuses on single-rate tensile extension to full failure, distinct from ISO 8340 which tests sustained constant tensile loading.
ASTM C1135 Standard Test Method for Determining Tensile Adhesion Properties of Structural Sealants
ASTM C1135 measures the tensile stress and elongation behavior of structural sealants when adhered between two rigid substrate panels — replicating the stress state of a structural glazing joint where the sealant acts as a structural link between glass/panel and the metal framing system. Quantify tensile adhesion, tensile stress at graded elongations, ultimate tensile strength and failure mode.
ISO 11527 Buildings and civil engineering works — Sealants — Test method for the determination of stringiness.
ISO 11527 quantify the stringiness (thread-drawing cohesive property) of uncured, wet-applied one-component construction sealants. Stringiness is measured as the maximum stretch length of a continuous filament pulled from fresh sealant before the thread breaks, recorded in millimetres. The result is expressed in millimetres (Lₘₐₓ).
ASTM C794: Standard Test Method for Adhesion-in-Peel of Elastomeric Joint Sealants
ASTM C794 test method covers a laboratory procedure for determining the strength and characteristics of the peel properties of a cured-in-place elastomeric joint sealant, single- or multicomponent, for use in building construction.
FAQ about ISO 8339 Building Construction Sealants Tensile Test Fixture
Q1: What standard does UnitedTest’s sealant tensile fixture follow?
A1: Primary standard ISO 8339:2005 (current active version); compatible with BS EN ISO 8339, GB/T 13477.8-2017, paired with ISO 13640 standard test substrates.
Q2: Can this fixture test low-temperature tensile performance of sealants?
A2: Yes, the fixture works with UnitedTest UTM temperature chambers (-20°C ~70°C) to conduct climate tensile tests referenced in ISO 8340.
Q3: Does UnitedTest supply matching aluminum/glass/mortar substrates together with the fixture?
A3: Standard anodized aluminum substrate blocks are included; glass and mortar substrate inserts are optional add-ons at extra cost.
Q4: Is the fixture compatible with non-UnitedTest brand universal testing machines?
A4: Custom crosshead adapters for Shimadzu, Instron, MTS and other UTM brands are available upon customer request.
Q5: Why Choose UnitedTest for Your ISO 8339 Testing Setup?
A5: UnitedTest is a global leader in materials and structural testing equipment, supplying universal testing machines, dynamic fatigue testers, impact testers, and a comprehensive range of test fixtures compliant with ISO, ASTM, EN, and DIN standards.
Key advantages for ISO 8339 sealant testing:
One-source responsibility — UTM, fixture, load cell, and chamber all from UnitedTest, eliminating interface issues.
Customization — fixtures are designed and produced according to required sample sizes and test needs, with competitive pricing and fast delivery.
Cross-brand compatibility — accessories work with UnitedTest machines as well as Instron, MTS, Zwick, and others.
Standards expertise — UnitedTest mechanical test fixtures and clamps comply with a wide range of international standards, ensuring reliable and accurate results.
Global support — expert technical assistance for installation, calibration, and method setup.
Require More Customized Solutions?