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D3535-07 – Standard Test Method Technical Guide
ASTM D3535-07a (Reapproved 2021) provides a definitive test method for evaluating the creep resistance of adhesives used in the production of structural glued laminated timber (glulam). This test is critical for qualifying adhesives intended for building products exposed to the elements, including marine and general construction environments.
📐 Test Specimen: Structural Glued-Laminated Timber
The specimen under evaluation is a structural-glued-laminated timber (glulam) assembly. As defined in the standard, this is an engineered, stress-rated product comprising laminations bonded with the candidate adhesive. The grain of all laminations must be approximately parallel longitudinally. Adhesives tested must be suitable for bonding wood, including treated wood, for general construction, marine use, or other uses where a high-strength, waterproof bond is required.
Laminations may be comprised of pieces end-joined to form any length, of pieces placed or glued edge-to-edge to make wider ones, or of pieces bent to curved form during gluing, aligning with the requirements of ANSI/AITC A190.1.
| 🟦 Term | 📏 Definition from D3535 |
|---|---|
| Glulam | Synonym for structural-glued-laminated timber. |
| Structural-Glued-Laminated Timber | An engineered, stress-rated product of a timber laminating plant comprising assemblies of specially selected and prepared wood laminations securely bonded together with adhesives. |
⚙️ Creep Testing Procedure and Environmental Exposure
This test method subjects glued laminations to a constant static load under various combinations of temperature and relative humidity. The amount of creep—the time-dependent deformation of the assembly—is the primary measurement of adhesive performance. The standard requires the use of a reliable loading apparatus (referencing Specification A125 for steel springs). The entire procedure is designed to simulate long-term exterior exposure conditions.
| 🟦 Referenced Document | 📐 Relevance to D3535 |
|---|---|
| ASTM D2559 | Specification for Adhesives for Bonded Structural Wood Products for Exterior Exposure |
| ASTM D907 | Standard Terminology of Adhesives |
| ASTM A125 | Specification for Steel Springs, Helical, Heat-Treated (used in loading frames) |
| ANSI/AITC A190.1 | Standard for Wood Products—Structural Glued Laminated Timber |
✅ Units Compliance: Per ASTM D3535, the values stated in SI units are to be regarded as the standard. Values in parentheses are provided for information only.
📊 Performance Rating and Significance
The significance of this test method lies in its ability to rate the performance of an adhesive in laminated wood as measured by its resistance to creep under static load. It validates that the adhesive develops a high-strength, creep-resistant bond suitable for use in harsh environments. The test method is directly tied to ASTM D2559, the specification governing adhesives for bonded structural wood products under exterior exposure conditions.
🚨 Safety Note: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices prior to use.
❓ Frequently Asked Questions
🔍 What is the primary purpose of ASTM D3535?
To measure the resistance to creep under static loading for adhesives used in structural wood laminating, specifically under exterior exposure conditions.
💡 What types of wood products are evaluated?
The standard covers adhesives for bonding wood into structural glued-laminated timber (glulam), including treated wood, for general construction and marine use.
⚡ How is the testing environment defined?
Glued laminations are subjected to a constant load under various combinations of temperature and relative humidity to simulate exterior exposure.
📌 Which other ASTM standards are critical for this test?
Key referenced documents include ASTM D2559 (Specification for Structural Wood Adhesives), ASTM D907 (Terminology), and ASTM A125 (Specification for Steel Springs).