Standard Specification for Adhesives for Bonded Structural Wood Products for Use Under Exterior Exposure Conditions
|Publication Date:||1 September 2010|
This specification covers adhesives suitable for the bonding of wood, including treated wood, into structural wood products for general construction or other uses where a high-strength, durable adhesive bond is required.
This specification includes test methods that may be referenced by specific product standards for the evaluation and approval of structural wood adhesives. Methods are included to evaluate adhesives intended for use in exterior exposure, which are characterized and defined by two distinct service classes as described in 1.3.
NOTE 1-Consult the Commentary in Appendix X1 regarding the intent and limitations of each test method contained in this specification.
Description of Bondline Performance-It is recognized that structural wood adhesives are used in various applications and under various levels of severity in terms of moisture content, loading, cyclic and seasonal weather conditions, heat exposure and other use conditions. It is the intent of this standard to determine the suitability of an adhesive for use under various levels of severity and conditions of use in accordance with specific and appropriate test methods and requirements. For use in this standard, structural wood adhesives are separated into two classes described in terms of conditions of use, and severity of environmental exposure including the amount of moisture.
NOTE 2-This standard does not contain specific tests outlined for different chemical types of adhesives.
Description of Adhesive Service Class A-This service class is characterized by its limited exposure to the weather, including low moisture content conditions and is sometimes referred to as a Protected Service or Limited Moisture Exposure environment. In this service class, exposure of adhesive bondlines in structural wood products to exterior environment is limited to those such as during transportation, construction and accidental exposure where the material may be subjected to a limited number of cycles of short-term wetting and drying.
Description of Adhesive Service Class B-This service class is described wherein adhesive bondlines in structural wood products are subjected to full and repeated or continuous exposure to the weather including high moisture content conditions. This exposure may include fresh and saltwater marine applications as well as possible ground contact. This service class has traditionally been refereed to as Exterior or Wet Service.
NOTE 3-While the two adhesive service classes for structural wood adhesives are described or characterized in 1.3.1 and 1.3.2 the definitions for Adhesive Service Class A and Adhesive Service Class B adhesives are found in Terminology 3.2.2 and 3.2.3 respectively.
Strength and durability requirements of the adhesive in Service Class A are based on the performance of the adhesive in laminated wood as measured by:
Resistance to shear by compression loading after conditioning to the target moisture content indicated in 14.2.3 and meeting requirements in 14.4.
Resistance to delamination during exposure to three cycles of vacuum pressure wetting followed by drying at elevated temperature as indicated in 15.3 and meeting requirements in 15.4.
Resistance to creep under static load by subjecting test specimens to a specified shear stress and exposing one set of test specimens to an environment of elevated temperature and ambient humidity and another set to an environment of high humidity and meeting requirements set forth in 16.3.
Strength and durability requirements of the adhesive in Service Class B are those listed in 1.4 and in addition shall include:
Conducting supplemental durability testing in accordance with Section 17. The supplemental durability testing shall be completed using either Test Method D3434 or CSA O112.9-10, Clause 5.5 as set forth in 17.2 and meeting requirements in 17.3 (Note 4).
NOTE 4-Test Method D3434 and CSA O112.9-10, Clause 5.5 are both considered sufficient to demonstrate a higher level of adhesive durability required and consistent with the indicated service environment. Although both methods are considered sufficient to demonstrate a higher measured level of adhesive durability, no documented level of equivalency with the two methods is stated or implied.
For marine applications the adhesive shall be evaluated in accordance with Section 15 using salt water.
For applications involving chemical treatment, the adhesive shall be evaluated in accordance with Sections 14-17 using representative samples of treated wood.
NOTE 5-When using chemically treated wood, compatibility between the treatment, adhesive, and wood is to be considered and agreed upon between the chemical manufacture and the user.
NOTE 6-Additional durability testing may also be required as specified by individual product standards. Consult the Commentary in Appendix X1 for additional information and guidance as to the type of durability testing that may be appropriate to supplement this specification when characterizing the adhesive for suitability with specific wood products.
The evaluation of binder adhesives is beyond the scope of this specification.
The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.
The text of this specification references notes, footnotes and a commentary which provide explanatory material. These notes, footnotes and commentary (excluding those in tables and figures) shall not be considered as requirements of the specification.
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 and health practices and determine the applicability of regulatory limitations prior to use.
*A Summary of Changes section appears at the end of this standard.