BS EN 15425-2008 pdf download.Adhesives — One component polyurethane for load bearing timber structures — Classification and performance requirements.
This BS EN 15425 establishes a classification for one component polyurethane adhesives according to their suitability for use in pre-fabricated timber components for structural use In defined climatic exposure conditions, and specifies performance requirements for such adhesives for the industrial manufacture of load- bearing timber structures only.
The performance requirements of this European Standard apply to the adhesive only, not to the structure. This European Standard does not primarily cover the performance of adhesives for the production of wood- based panels.
This European Standard is primarily Intended for the use of adhesive manufacturers and for the use in timber structures bonded with adhesives, to assess or control the quality of adhesives. This European Standard only specifies the performance of an adhesive for use in an environment corresponding to the defined conditions.
Such an adhesive meeting the requirements of this European Standard for its type is adequate for use in a load-bearing timber structure, provided that the bonding process has been carried out according to an appropriate product standard.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
EN 302-1, Adhesives for load-bearing timber structures – Test methods – Part 1: Determination of bond strength in longitudinal tensile shear strength
EN 302-2, Adhesives for load-bearing timber structures – Test methods – Part 2: Determination of resistance to delamination
EN 302-3, Adhesives for load-bearing timber structures – Test methods – Part 3: Determination of the effect of acid damage to wood fibres by temperature and humidity cycling on the transverse tensile strength
EN 302-4, Adhesives for load-bearing timber structures – Test methods – Part 4: Determination of the effects of wood shrinkage on the shear strength
EN 923:2005, Adhesives – Terms and definitions
EN 1995-1-1, Eurocode 5: Design of timber structures — Part 1-1: General – Common rules and rules for buildings
EN 15416-2, Adhesives for load bearing timber structures other than phenolic and aminoplastic – Test methods – Part 2: Static load test of multiple bondlirie specimens in compression shear
If a larger average ratio is obtained, the test may be continued for a second period of 26 weeks and a second assessment shall be performed after a total of 52 weeks under load. The average ratio of the relative creep value after 52 weeks, RC1 (52 weeks), shall not be larger than 1.15. The load must not be removed from the samples between the two test periods.
6 Test methods
6.1 General
The following test methods shall be used for establishing the requirements given in Clause 5 of this European
Standard.
6.2 Determination of bond strength in longitudinal tensile shear strength
Tests shall be made in accordance with EN 302-1 with glue line thickness 0.1 mm and 0,5 mm instead of 0.1 mm and 1,0 mm as stated in EN 302-1. Climatic treatments shall be performed according to Annex A.
Test samples subject to climatic treatment A6 and A7 shall be wrapped airtight before treatment to reduce moisture loss. The samples shall be tested immediately after removal from the climate chamber In a testing machine supplied with a temperature-controlled chamber.
6.3 DetermInation of resistance to delamination
Tests shall be made in accordance with EN 302-2.
6.4 DeterminatIon of tensile strength perpendicular to the bondline after climatic treatment
The test shall be made in accordance with the principles described in EN 302-3, but with samples made from untreated beech wood (Fagus sylvatica L) with a density at(12 ± 1) % moisture content of (700 ± 50 kg/rn3).
NOTE To ensure that no adhesive is lost from the test area, both sides of one of the two pieces of wood to be bonded together can be prepared with small wooden ledges made from beech wood as shown in Figure 1. The wooden ledges are glued on both sides of the wood with suitable equipment using a PVAC- adhesive. Care should be taken during the gluing of the ledges to avoid the PVAC- adhesive polluting the later glue line area.
After curing of the PVAC-adhesive, the test pieces are bonded and produced as described in EN 302-3.BS EN 15425-2008 pdf download.