BS 15416-1:2017 pdf download – Adhesives for load bearing timber structures other than phenolic and aminoplastic — Test methods Part 1 : Long-term tension load test per- pendicular to the bond line at varying climate conditions with specimens perpendicular to the glue line (Glass house test)
5 Method
5.1 General The specimens shall be produced following EN 302-3, but with specimens made from untreated beech wood (Fagus sylvatica L.) with close contact and 0,5 mm thick glue line for application areas “Special purpose” and “General purpose”, and a close contact glue line for application area “Finger joints”.
5.2 Selection of timber The beech wood boards from which the specimens are cut shall be free from knots, straight grained and shall have a density of (700 ± 50) kg/m 3 at 12 % moisture content. The timber prior to specimen manufacture shall be conditioned in a climate chamber at storage conditions of (20 ± 2) °C and (65 ± 5) % relative humidity (hereafter climate [20/65]). The moisture content shall be (12 ± 1) %. Each beech wood board shall have a width of at least 150 mm, a length of at least 750 mm and a thickness of at least 35 mm, and shall be used to manufacture one test stick as shown in Figure 3, a) and b). The annual ring orientation of both components glued together shall be roughly co-linear and with an angle of the growth rings in the range of 30° and 60°.
5.3 Production of the test sticks In total, 5 sticks with a cross section of 50 mm × 60 mm (after bonding and final preparation) and a length of at least 700 mm, enabling the cutting of 8 test specimens and 2 spare specimens from each stick of the specimen type described in EN 302-3, shall be manufactured for each glue line thickness. Alternatively, longer sticks can be pre-assembled into sub-sections of at least 300 mm prior to bonding, providing sufficient matched samples for cutting the required number of specimens. Not more than 8 h before the bonding, the boards are planned to their final thickness. For test pieces with a 0,5 mm thick glue line, each stick is prepared in an appropriate manner to ensure that the correct glue line thickness is achieved and to ensure that there is no loss of adhesive during the bonding of the test sticks. The manufacture and build-up of the test sticks shall in principle follow the scheme shown in Figure 3, a) and b). The adhesive shall be used in accordance with the recommendations of the adhesive manufacturer. An alternative way is to use radial/semi radial cut boards with the correct annual ring angle (30° to 60°), split it and make test sticks with the annual rings roughly co-linear as shown in Figure 4, a) and b).
5.4 Cutting of the test pieces and build-up of the test batches Cutting to single test specimens shall be done at the earliest 7 days after the bonding. The 10 specimens for each group of test pieces are made up of two specimens from each stick/group of sub-sections. Figure 5 gives an overview of the 10 specimens derived from each stick/group of subsections for the determination of the tensile strength perpendicular to the glue line.
NOTE For details of
cutting, see EN 302–3:2013, Clause 5 and Figure 2.
5.5 Test procedures 5.5.1 General The test procedure shall consist of the following test series:
a) short-term testing of a control batch BC of 10 specimens in ramp loading. The specimens are tested after 14 days of conditioning in climate [20/65] subsequent to gluing;
b) long-term testing of 3 batches (BD3, BD6 and BD12), each consisting of 10 specimens. Each batch shall be subjected to a different duration of load time being 3 months (BD3), 6 months (BD6) and 12 months (BD12). All batches shall be subjected to the same constant stress level specified below. At the end of each loading period, all specimens of the respective batch not having failed shall be unloaded, reconditioned in climate [20/65] and then tested for residual tensile strength perpendicular to the glue line in ramp loading.BS 15416-1 pdf downlaod.