EN 302-8:2023/prA1

Overview

EN 302-8:2023/prA1 is a European standard amendment focused on adhesives for load-bearing timber structures, specifically detailing the test methods for assessing the static load capacity of multiple bond line specimens under compression shear. Developed by CEN Technical Committee CEN/TC 193, this document clarifies and updates the procedures for evaluating the resistance of adhesive bonds to static loads in timber construction applications. It is essential for manufacturers, engineers, and certification authorities involved in timber adhesive quality assurance and classification.

This standard is applicable to adhesives used in load-bearing timber structures and supports compliance testing aligned with related standards such as EN 301, EN 15425, EN 16254, EN 17334, and EN 17418. It primarily aims to provide performance data for classifying adhesives based on their suitability in different climatic environments.

Key Topics

• Static Load Testing: Specifies a method to evaluate the resistance of adhesive bonds between timber elements to static compression shear loads-critical for ensuring structural integrity in timber constructions.

• Multiple Bond Line Specimens: The test procedure uses specimens with several bonded joints to replicate realistic load-bearing conditions found in engineered wood products.

• Climate Treatment Cycles: The amendment introduces modifications to climate treatment parameters, especially relative humidity levels in conditioning cycles, optimizing reproducibility and relevance to real service conditions. For example:

  • Adjusted relative humidity for low humidity cycles from (10 ± 5)% to <10% to reflect practical testing environments.
  • Clarification on achieving climate cycles using climate chambers or heating chambers.

• Adhesive Classification: Allows for classification of adhesives based on their capacity to withstand static loads after being subjected to various climatic treatments, contributing to design selections in different environments.

• Limitations: This method is intended for adhesive classification and quality assessment, not for structural design calculations or direct prediction of on-site performance.

Applications

• Quality Control for Adhesives: Enables adhesive manufacturers to validate product performance against static loads for use in timber structures.

• Compliance Verification: Supports testing laboratories in confirming compliance with harmonized European standards related to adhesives in timber construction.

• Product Development: Assists R&D teams in evaluating the durability and suitability of new adhesive formulations in different climate scenarios.

• Timber Construction Safety: Provides engineers and designers with critical data about adhesive bond strength, aiding in material selection for safe load-bearing timber elements.

• Environmental Conditioning Tests: Helps understand how constant loads combined with varying moisture and temperature conditions affect adhesive bond strength over time.

Related Standards

• EN 301: General test methods for adhesives used in timber constructions.
• EN 15425, EN 16254, EN 17334, EN 17418: Other adhesive standards focusing on product-specific requirements and performance criteria in timber structures.
• EN 302 Series: Part 8 is one segment of a broader series of test methods addressing adhesive performance for wood structures.
• EN 1995 (Eurocode 5): Structural design of timber buildings, which may use classification data from EN 302-8 for material specification.

Keywords: Adhesives for timber structures, static load test, compression shear, bond line specimens, load-bearing timber adhesives, EN 302-8 amendment, climate treatment cycles, adhesive classification, timber construction standards, European adhesives standards.