Bsi bs en 15416 2 2007 (2008)

untitled Li ce ns ed C op y B S I B en ch m ar k C er tif ic at io n, S ta nd ar ds A us tr al ia , 1 5/ 04 /2 01 0 01 1 5, U nc on tr ol le d C op y, ( c) B S I BRITISH STANDARD BS EN 15416 2 2007 Ad[.]

Adhesives for load

bearing timber

structures other than

phenolic and

aminoplastic —

Test methods —

Part 2: Static load test of multiple

bondline specimens in compression

shear

The European Standard EN 15416-2:2007 has the status of a

British Standard

ICS 83.180

This British Standard was

published under the authority

of the Standards Policy and

Strategy Committee

on 31 January 2008

© BSI 2008

National foreword

This British Standard is the UK implementation of EN 15416-2:2007

The UK participation in its preparation was entrusted to Technical Committee PRI/52, Adhesives

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

Compliance with a British Standard cannot confer immunity from legal obligations.

Amendments/corrigenda issued since publication

EUROPÄISCHE NORM December 2007

ICS 83.180

English Version

Adhesives for load bearing timber structures other than phenolic and aminoplastic - Test methods - Part 2: Static load test of multiple bondline specimens in compression shear

Adhésifs pour charpentes en bois portantes, de type autre

que phénolique et aminoplaste - Méthodes d'essai - Partie

2 : Essai de charge statique des éprouvettes à plan de joint

multiple en cisaillement par compression

Klebstoffe für tragende Holzbauteile ausgenommen Phenolharzklebstoffe und Aminoplaste Prüfverfahren -Teil 2: Statische Belastungsprüfung an Prüfkörpern mit mehreren Klebstofffugen bei Druck-Scherbeanspruchung

This European Standard was approved by CEN on 10 November 2007.

CEN members are bound to comply with 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 Management 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 Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION

C O M I T É E U R O P É E N D E N O R M A L I S A T I O N

E U R O P Ä I S C H E S K O M I T E E F Ü R N O R M U N G

Management Centre: rue de Stassart, 36 B-1050 Brussels

© 2007 CEN All rights of exploitation in any form and by any means reserved

worldwide for CEN national Members.

Ref No EN 15416-2:2007: E

Contents Page

Foreword 3

1 Scope 4

2 Normative references 4

3 Principle 4

4 Apparatus 4

5 Selection and preparation of wood 7

6 Test procedure 11

7 Expression of results and test report 12

Bibliography 13

Foreword

This document (EN 15416-2:2007) 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 by publication of an identical text or by endorsement, at the latest by June 2008, and conflicting national standards shall be withdrawn at the latest by June 2008

This European Standard is one of a series dealing with test methods for adhesives for use in load bearing timber structures The standard is published in support of Eurocode 5, Common unified rules for timber structures The series consist of six test methods to assess the performance of adhesives after specified heat and humidity treatments (EN 302, Parts 1 to 4, EN 15416-2 and EN 15416-3) and two test methods to characterize the working properties of the adhesive (EN 15416-4 and EN 15416-5) Requirements for the adhesives are stated in other standards, for instance requirements for one component polyurethane adhesives for load bearing timber structures are given in prEN 15425

Safety statement

Persons using this document should be familiar with the normal laboratory practice, in applicable This document does not purport to address all of the safety problems, if any, associated with its use It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any regulatory conditions

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom

1 Scope

This European Standard specifies a method of determining the ability of adhesive bonds to resist static load It

is applicable to adhesives used in load bearing timber structures

It is suitable for the following applications:

a) for assessing the compliance of adhesives according to prEN 15425;

b) for assessing the suitability and quality of adhesives for load-bearing timber structures

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 method is not intended for use to provide numerical design data and does not necessarily represent the performance of the bonded member in service It is not applicable to assessment of the suitability of adhesives for the manufacture of wood-based panels

Not applicable

3 Principle

Glued test pieces are subjected to a constant compression shear load under a series of three different climates Number of failures and the amount of deformation is measured after the test specimens have passed through all the climate cycles

4 Apparatus

4.1 Test jigs

The test equipment is in principle similar to that described in ASTM D 3535–07a, with the exception of the spring characteristics (Figure 1 and Figure 2)

Dimensions in millimetres

Key

1 top plate

2 spacer plate

3 base plate

4 tension rod x 4, diameter 15,9 mm

5 centre rod x 1, diameter 15,9 mm

Figure 1 —Test jig

Dimensions in millimetres

Key

1 top plate

2 spacer plate

3 base plate

4 tension rod x 4, diameter 15,9 mm

5 centre rod x 1, diameter 15,9 mm

Figure 2 — Dimensions of plates and rods

If equipment according to ASTM D 3535–07a is used, distance blocks need to be placed over and under the specimen The distance blocks shall be prepared in such a way that the two contact surfaces, between the distance block and the jig and between the distance block and the specimen, are parallel Blocks produced from several pieces of plywood bonded together have been found suitable Distance blocks made by metal should be avoided Dimension of distance blocks: 47,6 mm × 50,8 mm × ca 100,0 mm

NOTE 1 Reduced height of test jig Since the length of the specimens is shorter than in ASTM D3535–07a, the height

of the test jigs can be reduced correspondingly Minimum height of distance pieces: 25 mm

The spring shall have the following characteristics:

 outside diameter (unloaded): 105 mm;

 end fix: both ends fixed and grounded;

 free length: 320 mm;

 compression at maximum load 45 mm to 50 mm

NOTE 2 A spring rate of 81 N/mm has shown to be suitable

The heating chamber shall be capable of maintaining (70 ± 2) °C

The climate chamber shall be capable of maintaining the two climates (20 ± 2) °C and (85 ± 5) % relative humidity, and (50 ± 2) °C and (75 ± 5) % relative humidity

A universal testing machine is required for applying the load to the test jigs

5 Selection and preparation of wood

5.1 General

Untreated beech wood (Fagus sylvatica L.) with a density of (700 ± 50) kg/m³ at (12 ± 1) % moisture content

shall be used The material shall be straight grained and free from knots The angle of the annual rings to the surface to be bonded should be between 30° and 60° The parts, of which the specimen is built of, should have the same direction for the annual rings in the cross section by gluing (Figure 3)

Figure 3 — Orientation of annual rings in cross section of lamination

The wood shall be free of decay, machining defects (such as chipped grain, dubbed ends, feed roll polish, coarse knife marks and feed roll compression) and any drying defects such as case hardening, collapse, splits

or checks

Condition the wood at (20 ± 2) ˚C and a relative humidity of (65 ± 5) % until a moisture content of (12 ± 1) % has been obtained

Plane each lamination immediately before or not more than 4 h before applying the test adhesive

5.2 Preparation of laminations

Three laminated wood members shall be prepared in order to produce six test samples The laminated members shall be prepared from boards (16,0 ± 0,1) mm thick (after planning) by (60,0 ± 0,1) mm wide by (305,0 ± 0,1) mm along the grain Each laminated member shall be made from two outer lamellae as above and alternate spacers and wood sections for the inner part The wood sections shall be sliced from a third board identical to those above The wood sections shall be (28,5 ± 0,1) mm along the grain by (16,0 ± 0,1) mm thick by (60,0 ± 0,1) mm wide, see Figure 4

Spacers have to be made of suitable material, which makes it possible to remove them without destroying the specimen or disturb the positioning of the central pieces

Dimension of spacers: Length (6,4 ± 0,1) mm, thickness slightly less than the mid section pieces, width (60,0 ± 0,1) mm

NOTE 1 Spacers made from PTFE has shown to be a suitable material

Dimensions in millimetres

Figure 4 — Test assembly prior to bonding Figure 5 — Test assembly after planing

The centre layer of the assembly shall be made of 7 spacers and 8 wood sections alternately placed tightly adjacent to each others, see Figure 4

The wood sections should be slightly thicker than the spacers to obtain adequate pressure on the glue lines The gluing has to be done according to the supplier's recommendations Carefully clamp the mid section lengthwise to be sure that no movement will occur when pressing the whole piece together (Figure 4)

NOTE 2 It has been found that running a 13 mm wide piece of tape completely around the 15 loose pieces holds them together when mounting the laminations

The outer lamellas shall then be applied overlapping approximately 13 mm at each end and the entire assembly carefully clamped and the adhesive cured as recommended The positioning of the centrepieces shall be secured Spacers shall be removed and excess adhesive removed as soon as it can be done without moving the centrepieces The spacers shall be pushed gently (not impact driven) out After curing each three ply laminated assembly shall be trimmed along the sides to leave a width of (50,8 ± 0,1) mm, see Figure 5 After gluing, the specimens shall be conditioned for a minimum of 14 days in standard atmosphere 20 °C and

65 % RH before the load is applied Average thickness of the bond lines is registered

5.3 Preparation of test samples

The outer lamellas of the specimen shall then be notched with a width of (3,2 ± 0,1) mm The notches shall divide each centre piece symmetrically Notching should be to, but not beyond, the adhesive layer

From each of the three laminations, two test specimens with length (133,6 ± 0,1) mm are made, each containing four centre pieces Each specimen will then contain a total of 12 bond lines (nominal dimension 50,8 mm × 12,7 mm) for axial compression loading, providing a series of 6 pairs load bearing bond lines each

of which having a total nominal bond line area of 1 290 mm² The two outer lamellae are then trimmed, in order to make the terminal surfaces plane (Figure 6)

Figure 6 — The final shape of the specimen (48,0 mm × 50,8 mm × 133,6 mm)

6 Test procedure

6.1 Application of load

Prior to testing, use a straightedge and a razor blade to scribe lines perpendicular to every adhesive bond line for measuring possible slippage (see Figure 6) Insert the test specimens within the guides of the test jigs Position spacer plate no 2 on top Insert the spring and position spacer plate no 1 on top of the spring

Exert a gentle compression and position the corner nuts Load the entire unit in a compression testing machine to a total load of 3 870 N, resulting in a nominal shear stress in the bond lines of 3,0 N/mm²

Tighten the corner nuts by hand to maintain spring compression Position the keeper nut on the centre rod and tighten to within 9,5 mm of the top plate, thus retaining the spring in case of bond line failures Corner nuts shall be fixed within 2 min from start of applying load Climate treatment shall be started immediately after loading

The 6 clamped specimens are exposed for the following climate cycle according to Table 1

Table 1 — Climate treatment cycles Climate

(no) Temperature (°C) Relative humidity (%) Expected equilibrium moisture

content (%)

Period (h)

Each 14 day climate cycle shall immediately follow the previous

NOTE If one has to move the jigs from one climate to another, this should be done in a gentle way and as quick as possible

6.3 Measurements and evaluation of result

The specimens need to be evaluated at regular intervals to discover possible failures At the end of the 42 day test period, the test jigs shall be removed from the climatic chamber

If at least 5 samples still are intact, unload the test specimens and measure the slippage (deformation) across the inscribed line for all glue lines on both sides to the nearest 0,01 mm and calculate the mean value Measurement of slippage shall be made immediately after unloading

NOTE Measurement of slippage can be made with a light microscope or by a digital camera with a pixel size not exceeding 0,001 mm

7 Expression of results and test report

The test report shall include, at least, the following:

a) statement that the test was carried out in accordance with this standard;

b) date on which the test was carried out and the date of the report;

c) manufacturer’s name and the chemical nature and origin of the sample of adhesive tested;

d) density of wood in kg/m³ at (12 ± 1) % moisture content;

e) application and bonding conditions used for the laminations including date of gluing;

f) glue line thickness in finished laminations;

g) if it comes to a breach, the number of days or hours should be stated in the existing climate cycles; h) slippage values obtained and method used for measurement of slippage