Overview
ISO 20152-2:2011 - Timber structures - Bond performance of adhesives - Part 2: Additional requirements specifies optional, jurisdiction-dependent performance requirements for wood bond lines used in prefabricated structural timber components. Prepared by ISO/TC 165, this part supplements ISO 20152-1 (Basic requirements) and addresses higher-risk conditions such as high‑temperature creep, high‑temperature shear rupture, and gap‑filling performance of adhesives for timber structures.
Key topics and technical requirements
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Scope and application
- Applies to bond‑line performance in prefabricated structural timber products (e.g., glulam, LVL) when additional qualification is required by product standards or local regulation.
- Requirements are optional and intended for situations needing elevated temperature or gap‑filling evaluation.
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High‑temperature creep resistance
- Tests at 180 °C or higher (see test method references).
- Performance limits: average creep displacement for all bonded cross‑sections per specimen shall not exceed 0.6 mm; maximum average creep at any single bonded cross‑section shall not exceed 2.9 mm after the prescribed load period.
- Load condition: maintained stress level of (2.1 ± 0.1) MPa for 2 h (adjusted for spring constant at temperature).
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High‑temperature shear strength
- Tests at 220 °C or higher, following the general principle of ASTM D7247.
- Bonded specimen performance is compared to matched solid wood control specimens; exposure durations or shear retention criteria are set in consultation with product standards, manufacturers, or evaluation agencies.
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Gap‑filling capability
- Evaluated for bond lines thicker than 1.0 mm (tests typically up to 2.0 mm).
- Performance criteria are subject to agreement between adhesive manufacturer and user; basic performance must conform to ISO 20152-1.
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Specimen preparation & materials
- Hardwood reference: hard maple (Acer saccharum / A. nigrum).
- Softwood references: lodgepole pine, black spruce, Douglas fir, or alternatives as specified.
- Oven‑dry specific gravity thresholds: ≥ 0.65 (hardwoods); ≥ 0.49 (softwoods).
- Conditioning and moisture control per ISO 3130 and adhesive manufacturer’s recommendations.
Practical applications and users
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Who uses ISO 20152-2:
- Adhesive manufacturers qualifying adhesives for structural timber.
- Timber product manufacturers (glulam, LVL, laminated veneer timber) validating production changes or new adhesives.
- Independent test laboratories, certification bodies, and code evaluation agencies establishing compliance evidence.
- Regulatory authorities and design engineers assessing fire‑exposed or high‑temperature performance of bonded timber assemblies.
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Practical benefits:
- Provides standardized tests and acceptance criteria for demanding service conditions (fire protection, thick bond lines, high‑temperature exposure).
- Supports product qualification, code compliance, and consistent lab testing practices.
Related standards
- ISO 20152-1: Basic requirements (companion document)
- ISO 3130: Moisture content determination
- ISO 12579: Shear strength test methods for glue lines
- ASTM D7247: Elevated temperature shear strength testing principles
Keywords: ISO 20152-2, timber structures, bond performance, adhesives, high temperature creep, shear strength, gap filling, glulam, LVL, adhesive qualification.