ISO 8340 Building Sealant Maintained-Extension Tensile Test

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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.

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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.

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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.

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ISO 8340 Sealant Tensile Properties at Maintained Extension Tester | UnitedTest

ISO 8340 tests tensile properties of building construction sealants under maintained constant tensile extension, instead of pulling specimens to immediate rupture. UnitedTest manufactures ISO 8340 compliant sealant testing machines for construction sealant durability assessment and quality control.

ISO 8340 is an international standard for building construction sealants, specifying the method to determine tensile properties under maintained extension. Unlike conventional tensile tests that load samples until instant breakage, this standard holds sealant specimens at a constant tensile elongation to examine long-term tensile behaviour, stress relaxation and resistance to permanent deformation of joint sealants.

It is widely used for construction joint sealant material qualification, formulation development, batch inspection and compliance verification for facade, window, expansion joint and civil engineering sealing applications. Test results help engineers evaluate sealant’s ability to sustain stretching loads over time without cracking or adhesive failure.

UnitedTest manufactures precision ISO 8340 sealant testing machines. Our equipment delivers stable static tensile loading and controlled maintained extension, meeting laboratory R&D, factory quality assurance and third-party certification requirements for building sealant performance evaluation.

Core Test Principle

Test specimens are assembled with sealant bonded between two parallel rigid substrate surfaces. Specimens are stretched to a predefined extension and held at that fixed elongation under controlled temperature conditions for 24 hours. After the holding period, any adhesion failure (separation between sealant and substrate) or cohesion failure (cracking inside sealant bulk) is observed and measured for damage depth.

Core idea: Simulate real‑world service where building joints stay persistently stretched, not just subject to quick pulling‑to‑break. It is deliberately different from ISO 8339, which pulls the sealant until rupture (“extension to break”). ISO 8340 answers the more service‑like question: if the joint stays open, will the sealant keep holding without debonding or creeping to failure?

Test Equipment required of ISO 8340 Building Sealant Maintained-Extension Tensile Test

Universal Tensile testing machine	Dual movable/fixed crosshead design with self-aligning swivel universal joint grips to eliminate eccentric off-axis loading Capable of cross‑head speed at 5.5 ± 0.7 mm/min
Test substrates	Mortar, anodized aluminium or glass (per ISO 13640). Alternative substrates may be used upon mutual agreement.
Spacers	12 mm × 12 mm cross‑section with anti‑adherent surface, for shaping sealant bead.
Anti‑adherent sheet	Polyethylene (PE) film for specimen moulding.
Tools	1. Water immersion container: Hold distilled water for hydrothermal cycles. 2. Separators (fixed‑extension blocks): To lock specimens at target elongation (25 %, 60 %, 100 % or agreed strain). 3. Measuring device: Resolution up to 0.5 mm, to measure failure depth.

Test Specimen Information:

- Sealant bead dimension: 12 mm × 12 mm cross‑section.

- Number: 3 replicates for each substrate and each test temperature.

- Substrate dimension:

- Mortar substrates: ~75 mm height, two pieces with gap for 12 mm sealant; side widths approx. 25 mm each.

- Anodized aluminium / glass substrates: ~75 mm height; side widths approx. 6 mm each.

ISO 8340 Building Sealant Maintained-Extension Tensile Test

Test Parameters & Stipulations

Pulling rate	5.5 ± 0.7 mm/min
Target maintained elongation	25 %, 60 %, 100 % of original joint width (or contract‑agreed value); corresponding stretched width: 15 mm, 19.2 mm, 24 mm
Holding time under fixed extension	24 h
Pre‑cooling for low‑temperature test	≥ 4 h storage at ‑20 ± 2 °C before stretching
Measurement resolution for failure depth	0.5 mm

Test Procedures for ISO 8340 Building Sealant Maintained-Extension Tensile Test

① Test at 23 ± 2 °C

Remove moulding spacers; mount specimens in tensile machine at ambient temperature.
Stretch at 5.5 ± 0.7 mm/min up to the target elongation percentage.
Insert separators to hold constant extension for 24 h at 23 °C.
Release fixed extension, inspect every sample, measure depth of adhesion or cohesion failure with 0.5‑mm‑scale instrument.

② Test at ‑20 ± 2 °C

Store specimens inside cold chamber ≥ 4 h at ‑20 ± 2 °C.
Remove spacers; stretch specimens inside cold environment to target elongation at specified rate.
Use separators and maintain fixed extension for 24 h at ‑20 °C.
Warm specimens back to 23 ± 2 °C, then observe and measure failure depth for each replicate.

Test report mandatory contents

Laboratory name, test date, standard reference, sealant name/type/colour/batch, substrate type, primer information, conditioning method, applied elongation percentage, failure depth of each specimen, any deviation from standard requirements.

Industry Application Fields

The method is used for building‑joint sealants, including:

Expansion and movement joints in concrete/masonry

Curtain‑wall and façade joints

Window/door perimeter glazing and frame seals

Glass‑to‑metal or glass‑to‑aluminium joints

Mortar/concrete panel joints

General construction weatherproofing and water‑tightness joints

Users: sealant manufacturers R&D/QC, independent labs, façade consultants, architects/specifiers, certification bodies, procurement and compliance teams

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
ASTM C1635	Adhesion/cohesion at fixed extension, including water immersion; explicitly comparable to ISO 8340 and ISO 10590.
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)

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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 exactly is ISO 8340 test?

A: ISO 8340:2005 is an international standard test method for building‑construction sealants. It stretches sealant test specimens to a fixed elongation and holds this extension for 24 hours, to check adhesion loss (interface peeling) and cohesion failure (internal cracking) under sustained tensile stress. It simulates long‑term joint stretching in real‑world building conditions.

Q2: Why is ISO 8340 test important for building sealants?

A: Building joints keep persistent tensile deformation caused by thermal movement, structural displacement, wind load. A sealant may pass quick pull‑to‑break test (ISO 8339) but fail under long‑time static stretch. ISO 8340 reveals hidden risks of debonding or internal cracking. It verifies whether sealants can keep watertight and air‑tight performance for facade, window and concrete expansion joints, supporting material selection and quality control for construction projects.

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

A: ISO 8339: Pull specimen continuously until rupture; measures tensile strength, elongation‑at‑break (short‑term dynamic pulling test).

ISO 8340: Stretch to target elongation and hold constant strain for 24 hours; observes adhesion / cohesion damage under sustained tension. They are complementary standards, both are widely required for construction sealant qualification.

Q4: What elongation levels are defined in ISO 8340? Can I use custom elongation?

A: Standard elongation values: 25 %, 60 %, 100 % of original joint width (original 12 mm sealant bead; stretched width:15 mm,19.2 mm,24 mm). Parties can agree to adopt other elongation percentages for project‑specific requirements.

Q5: What are Conditioning Method A and Method B? What is their difference?

A: Method A: 28‑day curing under 23 °C /50 %RH (basic curing condition).

Method B: After finishing Method A, run three heat‑water cyclic ageing cycles (70 °C oven + distilled‑water immersion). Then rest 24 h under standard climate before testing.

Note: Method B is laboratory pre‑treatment, not equivalent to real‑service long‑term durability simulation. Test parties shall agree on which conditioning to apply before starting the test.

Q6: Which substrates can be used for ISO 8340 specimens?

A: Standard substrates are mortar, anodized aluminium and glass (per ISO 13640). Alternative substrates are allowed if agreed between contracting parties. Sealant performance may vary greatly across different substrates, so substrate type must be clearly reported in test report.

Q7: How to judge test failure in ISO 8340? What data should be recorded?

A: After 24‑hour maintained extension, inspect each sample and measure failure depth (0.5 mm resolution) of adhesive failure (separation between sealant and substrate) or cohesive failure (cracks inside sealant bulk). The test report shall record failure depth for every individual specimen, not just pass/fail judgement.

Q8: How many specimens are needed for a complete ISO 8340 test batch?

A: Minimum 3 specimens for each substrate and each test temperature (23 °C and ‑20 °C). For example: testing on mortar + aluminium substrates: total 12 specimens.

Q9: Why choose ISO 8340 Test Machine, Sealant Maintained Extension Tensile Tester from UnitedTest?

A: UnitedTest manufactures ISO 8340 test machines for building construction sealants. Complete solution for maintained‑extension tensile test, covering 23 °C ambient and ‑20 °C low‑temperature testing, compliant with EN ISO 8340:2005. Ideal for sealant factories, third‑party labs & construction material R&D.

UnitedTest is a professional manufacturer of material testing equipment, supplying fully‑compliant **ISO 8340:2005 sealant maintained‑extension tensile test systems** for global sealant manufacturers, third‑party accredited laboratories, construction‑material R&D institutes and quality‑control departmentsUnitedTest.

Our ISO 8340 testing machine executes the core procedure of the standard: stretching sealant specimens at 5.5 ± 0.7 mm/min cross‑head speed, supporting 25 % /60 % /100 % or custom‑agreed elongation. Matching accessories include standard test fixtures, separators for locking maintained extension, temperature‑controlled refrigerated chamber for ‑20 °C low‑temperature test, oven and water‑immersion containers for Method A / Method B specimen conditioning.

✅ Full‑standard compliance: Meets requirements of EN ISO 8340:2005, compatible with ISO 8339, ISO 13640 related sealant test workflows.

✅ Integrated solution: Machine frame + special sealant test fixtures + low‑temperature enclosure + measuring tool, one‑stop setup for sealant adhesion‑cohesion evaluation under sustained extension.

✅ Flexible configuration: Supports mortar, anodized‑aluminium, glass substrate specimens. Software records test parameters and exports editable test‑report templates matching ISO 8340 report clauses.

✅ Wide application: Silicone sealant, PU sealant, MS polymer sealant, acrylic joint sealant for facades, windows and civil‑engineering joints.

✅ UnitedTest service**: Technical consultation for specimen preparation, on‑site commissioning, calibration support, after‑sales training for ISO 8340 test operation.

Why choose UnitedTest ISO 8340 test equipment?

Many laboratories use universal testing machines but miss dedicated fixtures and temperature accessories required for maintained‑extension holding phase. UnitedTest provides purpose‑built kits, avoiding human error during manual elongation‑holding and ensuring repeatable, audit‑ready test data for certification and project tender.

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

ISO 8340 Building Sealant Maintained-Extension Tensile Test

① Test at 23 ± 2 °C

② Test at ‑20 ± 2 °C

Test report mandatory contents

① Test at 23 ± 2 °C

② Test at ‑20 ± 2 °C