1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 302-3:2013Adhesives for load-bearing timber structures T e s t m e t h o d sPart 3: Determination of the effect of acid damage to wood fibres by temperature and humidity cy
2、cling on the transverse tensile strengthBS EN 302-3:2013 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 302-3:2013. It supersedes BS EN 302-3:2004, which is withdrawn.The UK participation in its preparation was entrusted to T e c h n i c a l C o m m i t t e e P
3、 R I / 5 2 , A d h e s i v e s .A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institut
4、ion 2013. Published by BSI Standards Limited 2013.ISBN 978 0 580 75257 5 ICS 83.180 Compliance with a British Standard cannot confer immunityfrom legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 April 2013.Amendments issue
5、d since publicationDate T e x t a f f e c t e dBS EN 302-3:2013EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 302-3 March 2013 ICS 83.180 Supersedes EN 302-3:2004English Version Adhesives for load-bearing timber structures - Test methods - Part 3: Determination of the effect of acid damage to
6、wood fibres by temperature and humidity cycling on the transverse tensile strength Adhsifs pour structures portantes en bois - Mthodes dessai - Partie 3: Dtermination de linfluence de lattaque dacide des fibres de bois, rsultant de traitements cycliques en temprature et humidit sur la rsistance la t
7、raction transversale Klebstoffe fr tragende Holzbauteile - Prfverfahren - Teil 3: Bestimmung des Einflusses von Sureschdigung der Holzfasern durch Temperatur- und Feuchtezyklen auf die Querzugfestigkeit This European Standard was approved by CEN on 5 February 2013. CEN members are bound to comply wi
8、th the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Mana
9、gement Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same st
10、atus as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Mal
11、ta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2013 CEN All rights
12、 of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 302-3:2013: EBS EN 302-3:2013EN 302-3:2013 (E) 2 Contents Page Foreword 3 Introduction .4 1 Scope 6 2 Normative references 6 3 Principle 6 4 Apparatus .6 5 Method 7 5.1 Selection of timber.7 5.2 Pr
13、eparation of the bonded assemblies7 5.3 Preparation of the test pieces 9 5.4 Number of test pieces .9 5.5 Climatic and cyclic storage conditions .9 5.6 Test procedure .9 6 Expression of results . 10 7 Test report . 10 7.1 The adhesive . 10 7.2 Preparation of test pieces and testing procedures . 10 7
14、.3 Test results 11 Bibliography . 12 BS EN 302-3:2013EN 302-3:2013 (E) 3 Foreword This document (EN 302-3:2013) has been prepared by Technical Committee CEN/TC 193 “Adhesives”, the secretariat of which is held by AENOR. This European Standard shall be given the status of a national standard, either
15、by publication of an identical text or by endorsement, at the latest by September 2013 and conflicting national standards shall be withdrawn at the latest by September 2013. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/
16、or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 302-3:2004. The following modification has been made: The amendment in A1 has been included in the standard. According to the CEN-CENELEC Internal Regulations, the national standards o
17、rganizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembou
18、rg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 302-3:2013EN 302-3:2013 (E) 4 Introduction This document is one of a series dealing with adhesives for use with timber structures, and is published in suppo
19、rt of EN 1995, Eurocode 5: Design of timber structures. The series consists of three classification and performance requirements for adhesives for load-bearing timber structures, phenolic and aminoplastic adhesives (EN 301), one component polyurethane adhesives (EN 15425) and emulsion polymerised is
20、ocyanate adhesives (prEN 16254), and all together eleven test methods (EN 302 Parts 1 to 7 and EN 15416 Parts 2 to 5). These European Standards have the following titles. EN 301, Adhesives, phenolic and aminoplastic, for load-bearing timber structures Classification and performance requirements EN 1
21、5425, Adhesives One component polyurethane for load bearing Classification and performance requirements prEN 16254, Adhesives Emulsion polymerized isocyanate (EPI) for load-bearing timber structures Classification and performance requirements EN 302, Adhesives for load-bearing timber structures Test
22、 methods Part 1: Determination of longitudinal tensile shear strength Part 2: Determination of resistance to delamination Part 3: Determination of the effect of acid damage to wood fibres by temperature and humidity cycling on the transverse tensile strength Part 4: Determination of the effects of w
23、ood shrinkage on the shear strength Part 5: Determination of maximum assembly time under referenced conditions Part 6: Determination of the minimum pressing time under referenced conditions Part 7: Determination of the working life under referenced conditions EN 15416, Adhesives for load bearing tim
24、ber structures other than phenolic and aminoplastic Test methods Part 2: Static load test of multiple bondline specimens in compression shear Part 3: Creep deformation test at cyclic climate conditions with specimens loaded in bending shear Part 4: Determination of open assembly time for one compone
25、nt polyurethane adhesives Part 5: Determination of conventional pressing time Safety statement Persons using this document should be familiar with the normal laboratory practice, if applicable. This document cannot address all of the safety problems, if any, associated with its use. It is the respon
26、sibility of the user to establish appropriate safety and health practices and to ensure compliance with any regulatory conditions. BS EN 302-3:2013EN 302-3:2013 (E) 5 Environmental statement It is understood that some of the material permitted in this standard can have a negative environmental impac
27、t. As technological advantages lead to better alternatives for these materials, they will be eliminated from this standard to the greatest extent possible. At the end of the test, it is recommended that the user of the standard take care to carry out an appropriate disposal of the wastes, according
28、to local regulations. BS EN 302-3:2013EN 302-3:2013 (E) 6 1 Scope This European Standard specifies a method for determining the effect on bond strength of damage to wood fibres caused by the action of acids from the adhesive or primer used in the gluing process during climatic cycling. It is suitabl
29、e for the following applications: a) for assessing the compliance of adhesives with EN 301, EN 15425 and prEN 16254; b) for assessing the suitability and quality of adhesives for load-bearing timber structures; c) for determining if the adhesive after bonding has a damaging influence on the strength
30、 of the wood due to chemical action. This test is intended primarily to obtain performance data for the classification of adhesives for load-bearing timber structures according to their suitability for use in defined climatic environments. This test is carried out on Norway spruce (Picea abies L.).
31、This method is not intended for use to provide numerical design data and does not necessarily represent the performance of the bonded member in service. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its appl
32、ication. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 1245, Adhesives Determination of pH ISO 5893, Rubber and plastics test equipment Tensile, flexural and compression types (consta
33、nt rate of traverse) Specification 3 Principle A joint between wooden adherends is submitted to defined temperature and humidity cycles and then strained to failure by a transverse tensile load. 4 Apparatus 4.1 Testing machine, which shall be either: a) a constant rate of loading machine, capable of
34、 maintaining a rate of loading of (5 1) kN/min; or b) a constant rate of traverse machine as described in ISO 5893. Special mounts are required (see Figure 1). One or both mounts shall be attached to the straining heads by a coupling, which permits self-alignment of the mounts whilst the test pieces
35、 are being pulled. 4.2 Climatic cabinets, which are enclosures with air circulation capable of maintaining the test pieces under the following conditions: a) (10 2) C at approximately (87,5 2,5 ) % relative humidity; BS EN 302-3:2013EN 302-3:2013 (E) 7 b) (50 2) C at approximately (87,5 2,5) % relat
36、ive humidity; c) (50 2) C with relative humidity lower than 20%. NOTE The velocity of the air circulation at a level of 0,5 m/s to 1,0 m/s has shown to be suitable. 4.3 Airtight glass enclosure, such as a desiccator with a lid is required, with the following dimensions: a) Volume 2 l to 10 l; b) Rat
37、io of height to width between 1/1 and 2/1. 5 Method 5.1 Selection of timber Carry out this test using Norway spruce (Picea abies L.) having a density of (450 25) kg/m measured at 12 % moisture content. Prepare one piece of spruce 60 mm x 60 mm in cross section and at least 1 600 mm in length or two
38、pieces with a length of 800 mm that are free from knots, straight-grained and with growth rings not wider than 2 mm and at 30 to 60 to the surfaces of the specimen. 5.2 Preparation of the bonded assemblies Cut the piece of wood lengthwise into two equal pieces of rectangular cross section and store
39、them in standard climate 20/65 to constant mass. Constant mass is defined as the mass attained when the results of two successive weighings over an interval of 24 h differ by not more than 0,1 % of the mass of the specimen. Condition the timber in standard atmosphere 20/65 (20 2) C and (65 5) % rela
40、tive humidity) for at least 7 days prior to bonding, to achieve a moisture content of (12 1) %. Not more than 8 h before bonding, plane each surface to be bonded to the final thickness of 25 mm. Remove any dust carefully. Do not touch or soil the prepared surface. For glue mixes, adhesive and harden
41、er blended before application, the glue line thickness shall be 0,5 mm by using 0,5 mm thick spacers. For separate application of adhesive and hardener, the glue line thickness shall be 0,1 mm by using 0,1 mm thick spacers. BS EN 302-3:2013EN 302-3:2013 (E) 8 Figure 1 Test piece and mounts for asses
42、sing the transverse tensile strength of bonded wooden assemblies Dimensions in millimetres Figure 2 Tensile test pieces cut out of the bonded wooden assembly Prepare sufficient spacers 60 mm x 45 mm x (0,5 0,05) mm or 60 mm x 45 mm x (0,1 0,02) mm. (At least ten spacers will be required for a piece
43、of wood 800 mm long.) Lay these on the cut surface of the wood spaced (35,0 0,5) mm apart with the lengths across the width of the cut surface. Fill the gaps between the spacers with adhesive. Ensure that adhesive is not lost from the test area. Clamp the pieces of wood together with the same orient
44、ation with respect to each other as they had before cutting. Apply a pressure of BS EN 302-3:2013EN 302-3:2013 (E) 9 (0,6 0,1) MPa relative to the area of the spacers. Maintain this pressure at (20 2) C and (65 5) % relative humidity for the time recommended by the adhesive manufacturer, or 24 h. Af
45、ter bonding and pressing, condition the assembly for a minimum of 7 days and a maximum of 14 days at (20 2) C and (65 5) % relative humidity. A longer conditioning time may be used if recommended by the adhesive manufacturer. Record the time elapsed between the preparation of the bonded assembly and
46、 the start of temperature cycling. 5.3 Preparation of the test pieces Using a sharp 25 mm diameter wood drill and a piece of wood under the assembly to prevent fraying at the edges of the hole, drill holes along the length of the assembly in the plane of the bond at distances between centres of alte
47、rnately (50,0 0,5) mm and (30,0 0,5) mm so that a series of bond lines (25 1) mm in length is produced (see Figure 2). Take care to ensure that the holes are accurately positioned. Plane the assembly symmetrically to (50,0 0,5) mm x (50,0 0,5) mm and cut out the test pieces (60 1) mm long as shown i
48、n Figure 2. 5.4 Number of test pieces Test a sufficient number of test pieces to provide eight valid results for the cyclic treatment and eight valid test results for the control test pieces. Stop the test after eight valid results. Results from tests for all test pieces in which a solid wood failur
49、e occurred at strength values below the requirement, or in which visual examination shows that the adhesive was not correctly applied, are invalid and shall be disregarded. 5.5 Climatic and cyclic storage conditions Store at least eight test pieces that are not from adjacent positions in the bonded assembly in the standard climate (20/65) until testing. Select at least eight test pieces for the cyclic treatment, which consists of four cycles, each of whic
