ISO 8339 Tensile Test for Building Sealants (Extension to Break)

Information on the most widely used ASTM standards within the materials testing industry

Descriptions of the most prominent lSO standards within the materials testing industry

Standards including EN, DIN, JlS, and more

Mechanical testing of polymer materials in the automotive industry is directly related to the safety of components and the reliability of the entire vehicle. UnitedTest can cover mechanical performance testing for automotive interior and exterior parts, as well as functional components, adapting to automaker standards and providing comprehensive testing solutions including tensile, impact, and fatigue tests.

Mechanical testing in the battery industry determines the tensile and puncture resistance of core components such as separators and electrodes, directly affecting battery safety and cycle life. UnitedTest can cover full-dimensional mechanical testing of battery materials, compatible with national and international standards, and provide customized testing solutions.

Mechanical testing in the consumer goods industry determines product durability and safety, such as impact resistance for toys and fatigue resistance for home appliances, making it core to compliance and quality. UnitedTest can cover mechanical tests for all categories of consumer goods, including tensile, impact, and hardness tests, compatible with national and international standards, and offers customized testing solutions.

In the field of medical and biomedical sciences, mechanical testing determines the safety and compatibility of implanted devices and biomaterials, making it a core part of regulatory approval. UnitedTest can cover a full range of tests including tensile, fatigue, and wear tests, compatible with national and international standards, and provides customized biomechanical testing solutions.

Material strength is a course that most engineering fields are required to study in university education. This interesting course is very practical and makes use of testing equipment in the materials laboratory.

Mechanical testing of industrial products and components is essential to ensure their load-bearing, fatigue resistance, and impact resistance, directly preventing production accidents and ensuring stable operation of equipment. UnitedTest can cover a full range of tests including tensile, hardness, and fatigue, complying with national and international standards, and provides customized industrial mechanical testing solutions.

Mechanical testing in the plastic pipe industry determines ring stiffness, impact resistance, and tensile performance, directly preventing pipe bursts and deformation risks. UnitedTest can cover full-dimensional mechanical testing of pipes, complies with ISO,ASTM,EN et.c, international standards, and provides customized testing solutions.

In the construction engineering and building materials industry, mechanical testing determines the compressive and tensile properties of materials such as concrete and steel, which is core to ensuring the safety and durability of buildings. UnitedTest can cover the full range of building material mechanical tests, complies with ISO, ASTM international standards, and provides customized testing solutions for compressive, tensile, and other properties.

Mechanical testing in the food and beverage industry involves the compressive and tensile performance of packaging and the safety of food texture, directly ensuring storage, transportation safety, and the eating experience. UnitedTest can cover all-dimensional mechanical testing for packaging and food texture, comply with national and international standards, and provide customized testing solutions.

Mechanical testing in the packaging industry determines the packaging's resistance to compression, impact, and tension, directly ensuring the safety of contents during storage and transportation. UnitedTest can cover comprehensive mechanical testing for packaging, complying with ISO, ASTM Standards, and provides customized testing solutions for compression, drop, tear, and more.

Mechanical testing in the transportation industry concerns the load-bearing and fatigue resistance performance of core components such as vehicles, tracks, and containers, directly ensuring transport safety and equipment durability. UnitedTest can cover mechanical testing for all types of transportation materials, complying with national and international standards, and provides customized testing solutions including tensile, fatigue, and impact tests.

Metallurgical testing examines the properties of metallic materials to determine if a particular metal is appropriate for its intended use.

Testing of polymer materials covers mechanical, thermal, and chemical properties, verifying strength, heat resistance, composition, and ensuring product quality and compliance.

UnitedTest offer world-class testing solution in testing for polymeric materials, including elastomers, thermoplastics, composites, coatings, and structural adhesives in a variety of industries.

Testing of rubber and elastomers is used to assess the various properties and performance of materials under different conditions. This is crucial for ensuring the safety, functionality, and quality of rubber and elastomer products used in industries such as automotive, construction, consumer goods, and aerospace.

Conduct adhesive testing using various testing methods to determine their performance and characteristics in applications across multiple industries such as aerospace, automotive, construction, packaging, industrial, medical, and energy, thereby supporting application development and quality assurance.

UnitedTest supply machine and testing solution for tension, compression, fracture toughness, direct shear, triaxial and ultrasonic velocity are common concrete and rock testing applications.

UnitedTest has helped a number of companies involved in the wood, paper, cardboard, and corrugated industry with their testing needs. Our materials testing systems are capable of testing raw materials, components, and finished products.

UnitedTest testing system is trusted by leading medical device manufacturers, universities, and medical research laboratories worldwide. Whether testing tissues or bioresorbable materials, stents, or sutures, UnitedTest offers a variety of single-actuator and dual-actuator systems to meet your biomedical testing needs.

Mechanical testing in the textile fabric industry determines core properties such as fabric tensile strength, tear resistance, and wear resistance, directly affecting product durability and safety. UnitedTest can cover comprehensive mechanical tests for textiles, complying with national standards / ISO standards, and provides customized testing solutions including tensile, tear, and puncture tests.

The mechanical testing of industrial components directly determines the load-bearing, fatigue resistance, and wear resistance of the parts, helping to avoid equipment failure risks. UnitedTest can cover a full range of tests including tensile, hardness, and fatigue, is compatible with ISO/ASTM/GB standards, and provides customized mechanical testing solutions for industrial components.

Mechanical testing in the glass-ceramics industry determines core properties such as flexural strength, hardness, and fracture toughness, directly helping to avoid brittleness and failure risks. UnitedTest can cover comprehensive testing for flexural strength, hardness, and fracture toughness, compatible with national and ISO/ASTM standards, and provides customized testing solutions.

Tensile test evaluates material resistance to stretching, measuring strength/elongation critical for quality control. UnitedTest offers universal tensile testers (10-600KN) compliant with ASTM/ISO standards, providing tailored solutions for metals, polymers, medical & industrial materials.

Compression test assesses material resistance to compressive loads, measuring strength/deformation critical for quality validation. UnitedTest offers compression testing machines compliant with ASTM/ISO standards, providing tailored solutions for concrete, plastics, metals and industrial components.

Flexural & Bend tests evaluate material resistance to bending forces, measuring strength, stiffness and ductility for quality assurance. UnitedTest provides flexural testing machines (3-point/4-point bend) compliant with ASTM/ISO standards, offering tailored solutions for composites, plastics, metals and construction materials.

Torsion Test evaluates material resistance to rotational forces, measuring torsional strength/ductility critical for fasteners, insulators, shafts. UnitedTest offers torsion testers compliant with ASTM A938/ISO 16047, providing tailored solutions for automotive, aerospace, fastener industries.

Fatigue Test assesses material durability under cyclic loading, critical for predicting service life of industrial components. UnitedTest offers fatigue testing systems (axial/bending/torsion) compliant with ASTM E466/ISO 12106, providing tailored solutions for automotive, aerospace and manufacturing sectors.

Peel Test measures material adhesion strength by evaluating resistance to peeling forces, critical for adhesives, films, packaging. UnitedTest offers peel testers compliant with ASTM D903/ISO 8510, covering 90°/180° peel tests, and tailored solutions for packaging, automotive, textile industries.

Impact Test evaluates material resistance to sudden shock loads, critical for assessing toughness and fracture risk. UnitedTest offers impact testers (Charpy/Izod/fall weight) compliant with ASTM E23/ISO 148, providing tailored solutions for metals, plastics, glass and industrial components.

Tear & Shear Test evaluates material resistance to tearing and shearing forces, measuring critical strength parameters for quality control. Tear tests (Elmendorf/trouser/trapezoidal) assess resistance to crack propagation in films/fabrics, while shear tests measure resistance to parallel forces in joints/bolts. UnitedTest provides universal testing machines (10KN-600KN) with specialized fixtures for both tests, compliant with ASTM D624/D3164 and ISO standards, serving automotive, packaging and construction industries.

Hardness test measures material's resistance to permanent indentation, critical for quality control. UnitedTest offers universal hardness testers (Rockwell/Brinell/Vickers) compliant with ASTM/ISO standards, plus tailored hardness testing solutions for diverse industrial needs.

Biaxial/triaxial tests evaluate material performance under multi-axis loads, critical for biomaterials, metals and composites. UnitedTest provides compliant testing machines (ASTM/ISO) for planar biaxial, static/fatigue triaxial tests, with tailored solutions for industrial & biomedical needs.

Friction and wear tests assess material resistance to friction, abrasion and wear, critical for industrial material performance validation. UnitedTest offers tribometers compliant with ASTM G99/ISO standards, covering pin-on-disk, four-ball tests, and tailored friction & wear testing solutions for diverse industries.

Pressure test evaluates material/component resistance to static/dynamic pressure, critical for sealing, strength and safety validation. UnitedTest offers pressure testing machines compliant with ASTM/ISO standards, covering burst, hold-pressure tests, and tailored solutions for industrial, automotive & medical sectors.

Fire test assesses material flammability, heat resistance and fire-retardant performance, critical for safety compliance across industries. UnitedTest offers fire testing equipment compliant with ASTM/ISO/UL standards, providing tailored fire test solutions for building materials, plastics and industrial components.

Non-destructive Test (NDT) evaluates material/component integrity without damage, critical for safety & quality across industries. UnitedTest offers ultrasonic/X-ray/magnetic particle NDT equipment compliant with ASTM/ISO standards, plus tailored NDT solutions for aerospace, automotive & manufacturing sectors.

ISO 8339 Construction Sealant Tensile Property Tester | UnitedTest

UnitedTest manufactures precision ISO 8339-compliant tensile testing machines built to measure tensile properties including elongation to break for building construction joint sealants in construction material labs and sealant manufacturing QC departments.

ISO 8339 Building construction — Sealants — Determination of tensile properties (Extension to break) establishes a standardized laboratory tensile testing procedure for construction joint sealants. The test stretches bonded sealant specimens continuously until total rupture to capture complete tensile mechanical performance data.

This standard quantifies two critical sealant characteristic metrics: secant modulus and elongation-at-break. These core parameters assess the elastic deformability, adhesive capacity and cohesive integrity of sealants under tensile stress. ISO 8339 implements single-speed tensile extension all the way to specimen failure, which differentiates it clearly from ISO 8340, the standard designed for sustained constant tensile load testing of sealants. Test outputs guide sealant formulation development, joint structure design and finished construction sealant batch qualification.

Core Test Principle

Standardized rectangular sealant bead is fully bonded between two parallel rigid substrate strips (mortar, anodized aluminium or glass).

The bonded specimen is pulled apart at a constant low crosshead speed until the sealant completely fractures (adhesive detachment from substrate or cohesive split inside sealant).

A continuous force-extension curve is digitally recorded throughout the full stretching process.

Two key performance metrics are mathematically derived from the curve:

Secant modulus: Stiffness of the sealant at a defined elongation level (typically 60% or 100% strain)

Elongation at break: Maximum stretch percentage the sealant can withstand before rupture

Post-test visual inspection classifies failure as adhesive (interface separation) or cohesive (internal sealant crack), to distinguish poor substrate adhesion vs weak bulk sealant elasticity.

Test Equipment required of ISO 8339 Tensile Test for Building Sealants (Extension to Break):

Tensile testing machine	Constant crosshead speed: \(5.5 \pm 0.7\) mm/min Equipped with digital recording system to generate continuous force/extension graphs Grips designed to firmly clamp the outer substrate sections without damaging the bonded sealant joint.
Standard Test Substrates	Three permitted rigid substrate types: Mortar panels (75 mm height, 12 mm thickness) Anodized aluminium sheets Float glass sheets Other substrates are allowed only with written agreement between testing parties.
Spacers	12 mm × 12 mm cross-section rigid spacers with anti-adhesive surface (to define fixed sealant bead thickness and width during casting).
Anti-Adherent Base Sheet	Polyethylene (PE) film to support uncured sealant during filling and initial curing; easily peeled off without damaging fresh sealant.
Environmental Conditioning Chamber	Ventilated convection oven: Stable temperature at (70 ± 2)°C for accelerated heat-water cycling (Conditioning Method B) Water immersion container: For distilled water soaking cycles at 23°C Refrigerated temperature chamber: Maintains -20°C for low-temperature tensile testing.

Test Specimen Information:

1, Specimen Geometry

Configuration: Sealant bead cast between two parallel substrate pieces, separated by 12 mm × 12 mm spacers

Substrate materials: Mortar, anodized aluminium, or glass (as per Figures 1 and 2 in the standard)

Spacer cross-section: 12 mm × 12 mm

Anti-adherent backing: PE film or similar, placed beneath the sealant during curing

Sealant bead dimensions: Controlled by the spacer geometry — the sealant fills the hollow volume formed by the substrates and spacers

2, Quantity: 3 test specimens prepared for each substrate type and each test temperature (so 3 specimens × 2 temperatures = 6 specimens minimum per substrate type).

Avoid air bubble formation.

Specimens set on edge to cure; spacers maintained in place during conditioning

Anti-adherent substrate removed as soon as possible after specimen assembly

3, Two Conditioning Regimes

3.1, Method A (Standard Ambient Cure): 28 days at (23 ± 2)°C and (50 ± 5)% RH

3.2, First complete Method A 28-day cure, then repeat three full environmental cycles:

3 days oven at (70 ± 2)°C

1 day distilled water immersion at 23°C

2 days oven at (70 ± 2)°C

1 day distilled water immersion at 23°C

After three cycles, rest specimens for 24 h under 23°C/ 50%RH before tensile testing.

Note: Method B simulates thermal/humidity exposure but does not represent long-term real-world durability.

Test Parameters & Stipulations

Tensile extension rate	(5.5 ± 0.7) mm/min
Specimens per temperature	3
Spacer dimensions	12 mm × 12 mm
Conditioning Method A	28 days at 23 ± 2°C, 50 ± 5% RH
Conditioning Method B	Method A + 3 heat/water cycles (70 ± 2°C oven ↔ 23 ± 2°C distilled water)
Secant modulus rounding	0.01 N/mm²
Elongation at break reporting	Nearest 5%

Sealant adhesion — Sealant shall be pressed onto the inner surfaces of the substrates.

Surface trimming — Sealant surface shall be trimmed flush with substrate and spacer faces.

Spacer retention — Spacers shall be maintained in place during conditioning.

Test Procedures for ISO 8339 Tensile Test for Building Sealants (Extension to Break)

Step 1 Specimen Casting & Initial Cure

Assemble substrate-spacer mould on PE film, fill cavity with mixed sealant (follow manufacturer primer/mixing guidance), de-air and level sealant surface, peel off PE film after skin formation, cure per Method A or B conditioning schedule with spacers retained.

Step 2 Pre-Test Temperature Stabilization

For +23°C test: Directly take conditioned specimens to lab ambient environment

For -20°C test: Transfer specimens into refrigerated chamber and hold for ≥4 hours to reach uniform low temperature.

Step 3 Machine Mounting

Remove top and bottom 12.5 mm spacers from the cured specimen; clamp the upper and lower rigid substrate ends into tensile machine grips symmetrically, keep sealant bead fully unobstructed between jaws.

Step 4 Tensile Extension to Rupture

Start tensile tester at fixed 5.5 mm/min crosshead speed; continuously record force vs extension curve until full sealant rupture occurs.

Step 5 Post-Test Classification

Visually identify failure mode for each specimen:

Adhesive failure: Clean separation between sealant and substrate surface.

Cohesive failure: Internal crack splitting the bulk sealant material.

Mixed adhesive + cohesive failure (record both percentages if partial separation occurs).

Industry Application Fields

ISO 8339:2005 is used across the building and construction sealant industry:

Building envelope / Façade engineering	Performance assessment of sealants for façade joints, curtain walls, and cladding systems
Windows & doors	Evaluating sealants for window and door perimeters — critical for weather tightness
Expansion joints	Testing sealants for building movement joints that must accommodate thermal and structural movement
General building sealing	Quality control and specification compliance for all types of construction sealing
Sealant manufacturing	R&D and quality laboratories for product development and batch verification
Third-party testing & certification	Independent testing bodies and certification organizations
Product standards compliance	ISO 8339 is referenced by ISO/DIS 11600 (Classification of elastomeric sealants) — used to determine secant tensile modulus and elongation at break for sealant classification into 25LM, 25HM, 20LM, 20HM, 12.5E, 12.5P, and 7.5 classes
Low-temperature performance	Evaluating sealant behavior at −20°C, simulating cold-climate service conditions
Heat/water exposure assessment	Method B conditioning evaluates effects of thermal and moisture cycling on tensile behavior

Related Stadard:

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	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
ISO 10590	Building Construction Sealants Determination of Tensile Properties of Sealants at Maintained Extension After Immersion in Water
ISO 19862	Buildings and civil engineering works — Sealants — Durability to extension compression cycling under accelerated weathering
ASTM C719	Standard Test Method for Adhesion and Cohesion of Elastomeric Joint Sealants Under Cyclic Movement (Hockman Cycle)

ISO 8339 vs. ISO 8340 — Side by Side

Feature	ISO 8339	ISO 8340
Test type	Extension to break	Tensile properties at maintained extension
Objective	Measure ultimate strength & ductility	Measure performance under sustained load
Procedure	Extend until rupture at 5.5 ± 0.7 mm/min	Hold at fixed elongation (e.g., 25%, 60%, 100%) for 24 h
Outputs	Secant modulus, elongation at break	Depth of adhesion/cohesion loss (mm)
Failure assessment	Recorded at moment of break	Measured after 24 h sustained extension
Role in ISO 11600	Determines LM/HM classification & elongation grades	Evaluates sustained-load durability
Complementarity	✓	✓

Keywords: UnitedTest ISO 8339 tester, ISO 8339 sealant tensile tester, construction sealant elongation to break test machine, building sealant tensile property testing equipment, ISO 8339 secant modulus elongation-at-break test for construction sealants, single-rate tensile extension sealant testing machine, difference between ISO 8339 and ISO 8340 sealant tensile test, joint sealant adhesion cohesion tensile performance analyzer, building construction sealant rupture tensile test instrument

A single column tensile tester is a sophisticated material testing instrument designed for measuring mechanical properties of various materials under tension, compression, bending, shear, and other loading conditions. As the name suggests, it features a single vertical column supporting a moving crosshead that applies force to test specimens.

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.

Vice Tensile test fixture for plastics is based on the test standatd ASTM D638, determination of the tensile properties of unreinforced and reinforced plastics in the form of standard dumbbell-shaped test specimens when tested under defined conditions of pretreatment, temperature, speed.

Q1: What is the core purpose of ISO 8339?

A1: This international standard defines a tensile test to measure two key mechanical properties of construction joint sealants: secant modulus and elongation-at-break. Specimens bonded to standard substrates are stretched continuously until rupture, generating force-extension curves to evaluate elasticity, flexibility and adhesive/cohesive performance under tension. It focuses on instantaneous full extension to break, not long-term sustained stretching.

Q2: What sealant applications does ISO 8339 cover, and what is excluded?

A2: It applies to all building joint sealants for facades, windows, concrete expansion joints, roofing and glazing. It does not cover industrial non-construction sealants, adhesives or caulks for consumer goods.

Q3: What is the difference between ISO 8339 and ISO 8340?

A3: They are complementary paired standards:

ISO 8339: Continuous stretching until complete rupture, measures secant modulus and break elongation (short-term instantaneous tensile behaviour).

ISO 8340: Holds specimens at fixed constant elongation for extended time, tests creep and stress relaxation (long-term sustained tensile performance).

Both are mandatory for full sealant mechanical characterization under most construction product standards.

Q4: What substrates are specified in ISO 8339 per ISO 13640?

A4: Three standard permitted substrates:

Mortar (standard for concrete joint testing)

Anodized aluminium (metal facade framing)

Float glass (structural glazing)

Other substrates are allowed only via written mutual agreement between testing parties.

Q5: What fixed cross-section size does the sealant bead have?

A5: The standard sealant cavity is 12 mm width × 12 mm thickness for all substrate types. Only the substrate overlap length differs:

Mortar: 25 mm bond overlap on each side

Aluminium/glass: 6 mm bond overlap on each side

Q6: How many replicate specimens are required for a valid test batch?

A6: Minimum 3 identical specimens per substrate type, per test temperature (+23°C and -20°C).

Q7: What three failure modes do I need to classify after rupture?

A7: Cohesive failure: Crack splits entirely inside the sealant bulk (indicates flexible, robust sealant core material).

Adhesive failure: Clean separation between sealant and substrate surface (sign of poor surface adhesion or missing primer).

Mixed failure: Partial adhesive + partial cohesive rupture on the same specimen (must record percentage split).

Q8: Why use anti-adherent PE film during specimen casting?

A8: PE film prevents uncured sealant from sticking to the base mould surface, and can be easily peeled off after skin formation without damaging the fresh sealant bead. Spacers stay in place for all curing/conditioning steps.

Q9: What precautions are required when filling the sealant mould?

A9: Avoid trapped air bubbles, fully press sealant against both substrate bonding surfaces, and trim the top surface flush with spacers to guarantee uniform bead geometry and consistent test results.

Q10: How does ISO 8339 differ from ASTM C1135 (US sealant tensile standard)?

A10: Geometry: ISO 8339 uses fixed 12×12 mm sealant bead; ASTM C1135 has alternative coupon dimensions.

Temperatures: ISO 8339 mandates -20°C cold testing; ASTM C1135 is ambient-only in base procedure.

Conditioning: ISO 8339 provides formal heat-water accelerated ageing (Method B); ASTM C1135 relies on separate ageing protocols.

Regional use: ISO 8339 for global/CE marking construction products; ASTM C1135 for North American building material certification.

Q11: Why is ISO 8339 testing essential for construction sealants?

A11: Provides core design parameters (secant modulus, break elongation) for architects and structural engineers to select sealants matching joint thermal movement tolerances. Low-modulus high-elongation sealants absorb concrete/glass expansion without cracking.

Validates cold-climate performance via mandatory -20°C testing, eliminating risk of brittle rupture in winter outdoor joints.

Clearly distinguishes adhesion vs cohesion failure modes to diagnose formulation or surface treatment defects (e.g. missing primer causing interfacial detachment).

Global harmonised test method for cross-border construction supply chains; accepted for EU CPR (Construction Products Regulation) CE marking technical files.

Enables side-by-side comparative screening of new sealant formulations during R&D and incoming raw material QC.

Accelerated Method B conditioning delivers fast preliminary ageing screening before multi-year outdoor weathering trials.

Production batch release quality control to guarantee consistent elasticity and adhesion across mass-produced sealant cartridges.

Defines maximum allowable joint opening for expansion joint design, preventing costly facade water leakage failures.

Q12: Which industrial sectors rely heavily on ISO 8339 compliance?

A12: Curtain wall & facade construction (structural silicone glazing sealants)

Residential/commercial window and door perimeter sealing

Concrete infrastructure (bridge, tunnel expansion joint compounds)

Roofing and waterproof joint sealant manufacturing

Architectural glazing and insulated glass production

Third-party accredited construction material testing labs

Sealant R&D and raw material formulation laboratories

Q13: What are the main limitations of the ISO 8339 test method?

A13: Only measures instantaneous short-term tensile rupture; cannot evaluate long-term creep/stress relaxation (requires ISO 8340).

Method B accelerated heat-water cycling is just comparative screening and does not replicate decades of natural UV/rain outdoor weathering.

Test results are substrate-dependent; sealant performance on mortar differs greatly from glass/aluminium, requiring separate testing for each application surface.

No cyclic repeated stretching simulation (ISO 19862 cyclic test required for long-term joint durability evaluation).

Single fixed slow pull speed cannot simulate rapid shock movement loads on building joints.

Q14: What mandatory information must an official ISO 8339 test report contain?

A14: Standard reference: ISO 8339:2005

Laboratory name and full test date

Sealant full identification: chemical family, colour, production batch number

Substrate material type (mortar / anodized aluminium / glass)

Primer product details (if applied before sealant casting)

Full description of conditioning (Method A or complete Method B cycling steps)

Secant modulus values per individual specimen + arithmetic average modulus

Elongation-at-break percentage for each replicate + mean elongation

Full failure classification (adhesive / cohesive / mixed) for every test coupon

Any deviations from standard specimen prep or test procedure

Q15: Why is the dual-temperature testing (23°C and −20°C) important?

A15: Building joints experience extreme temperature variations:

Behind dark glazing, sealant temperatures can exceed 70°C

In winter climates, sealants can drop to −20°C or below

Testing at both 23°C (representing moderate/service conditions) and −20°C (representing cold-climate extremes) reveals:

How the sealant's stiffness changes with temperature

Whether the sealant remains flexible enough at low temperatures to accommodate joint movement without brittle failure

The temperature-dependent ductility of the material

This dual-temperature data is essential for selecting sealants for buildings in varying climatic conditions.

Q16: What does the secant modulus tell us about a sealant?

A16: The secant modulus (σ = F/s) measured at a chosen elongation (typically 100% or 60%) indicates the stiffness of the sealant at that deformation level:

Low secant modulus → Flexible sealant that accommodates large joint movements with low stress (suitable for dynamic joints)

High secant modulus → Rigid sealant that resists deformation but may crack or debond under large movement (suitable for minimal-movement joints)

This directly informs sealant selection: high-movement joints (e.g., façade expansion joints) require low-modulus sealants; low-movement joints (e.g., perimeter sealing) can use higher-modulus products.

Q17: How should ISO 8339 results be interpreted for sealant selection?

A17: When evaluating sealant test data:

Check the secant modulus — Lower values indicate more flexible sealants suitable for high-movement joints.

Check elongation at break — Higher values indicate greater ductility and ability to accommodate extreme joint movement.

Check failure mode — Cohesive failure (within the sealant) is generally preferable to adhesive failure (at the interface).

Compare across temperatures — A good sealant maintains reasonable elongation at break even at −20°C.

Consider the conditioning method — Method B results show sensitivity to heat/water exposure, though not true durability.

We offer customization to meet your specific needs. Our expert team will collaborate with you to develop the perfect product for you