and hydrophilic primer for load bearing application P eter Niemz 1) - - PowerPoint PPT Presentation

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Oct 25, 2022 211 likes •452 views

Improvement of ash wood bonding quality with 1C-Polyurethane adhesive and hydrophilic primer for load bearing application P eter Niemz 1) , Gaspard Clerc 1) Joseph Gabriel 2) Dario Salzgeber 2), Thomas Strahm 3) 1) Bern University of Applied

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

Improvement of ash wood bonding quality with 1C-Polyurethane adhesive and hydrophilic primer for load bearing application

Peter Niemz1), Gaspard Clerc1) Joseph Gabriel 2) Dario Salzgeber 2), Thomas Strahm 3)

1)Bern University of Applied Science, Biel/CH2 ) Henkel & Cie., Sempach/CH, 3) neue Holzbau AG,

Lungern /CH peter.niemz@bfh.ch

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

  • 1. Introduction

volume change of softwoods and hardwoods from NFI 2 to NFI 3 in Switzerland (U. B. Brändli 2010)

volume change

softwoods

spruce fir pine larch swiss stone pine

  • thers

total [Mio. m³]

  • 7.55

2.96

  • 0.55

2.13 0.20 0.42

  • 2.40

[%]

  • 4.1

5.2

  • 4.1

11.0 9.2 41.5

  • 0.9

volume change

hardwoods

beech maple ash

  • ak

chestnut

  • thers

total [Mio. m³] 4.28 2.06 2.87 0.59 0.18 1.98 11.96 [%] 6.2 21.8 24.4 7.1 3.8 18.0 10.4

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

Problems softwood-hardwood for glulam

softwood hardwood

Costs (forest, roundwood): 80-100CHF/fm 45-75CHF/fm Costs glulam : 600CHF /m3 1700 (ash)-2000CHF/m3 (beech) «Baubuche» Pollmeier 650-780CHF/m3 Material using: Germany 2005: 61,1%, 2010: 49,5% (Mantau), rest for energy Objective: More using of hardwood for glulam, CLT, LVL from beech, «Baubuche», other wood based materials

pine, spruce beech, ash

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

  • 2. Properties of hardwood and softwood

property spruce beech ash

Denisty ,ϖ12 % (kg/m3) 300-430-640 540-700-900 450-690-860 MOE (bending) (MPa) 7.300-11.000-21.400 12.300-16.400 4.400-13.400-18.100 Compression strength (MPa) 33-50-79 41-62-99 23…52…80 Tensile strength (MPa) 21…90…245 57-135-180 70…165…293 Bending strength (MPa) 49-78-136 74-123-210 58..105…210

  • Max. swelling (%)

R=3,5-3,7 T=7,8-8,0 R=5,8 T=11,8 R=4,5-5,0 T=8,0-8,4 pH-Wert 4,0-5,3 5,8 5,8

Quelle: Wagenführ Holzatlas, 2000

Hot water extract (%) 2,0 1,9 2,9-6,8

Variant Acidic acid [mg/kg] Formic acid [mg/kg] ∑ [mg/kg] Ø pH Sample 1 Sample 2 Sample 1 Sample 2 Sample 1 Sample 2 Beech 113.9 114.5 9.58 9.58 123.5 124.1 123.8 5.39 Ash 225.6 227.5 50.72 50.72 276.3 278.2 277.3 5.18 Spruce 421.3 423.8 13.17 13.21 434.7 437.0 435.9 4.74

➢ hardwood higher swelling ratio in relation to softwood ➢ higher MOE, higher strength (also shear strength –delamination) Problems: delamination test according EN 302-2 why: ▪ higher stress during delamination ▪ different extractives

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

  • 3. Selected examples for using of hardwood in

the timber construction

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

Timber construction with beech and ash (Holzbau Beer/Switzerland)

6

for the crane («BauBuche») ash and beech

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

House of Natural Resources

ETH Zurich (glulam from ash wood)

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

Reinforcement from spruce with ash (timber conections)

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

used adhesives in the timber construction

Used adhesives in European Countries (Euwid 2005): Certification in Germany necessary, not in Switzerland MUF/MF 49%, PUR 15%, UF 12%, PRF 20%, sonstige 2% (EPI) Selected producers: ➢ MUF/MF: z.B. Dynea; BASF; AkzoNobel (GripPro=MF) ➢ PRF: Dynea/Norge, Oxiquim/Chile ➢ 1C-PUR; 2C-PUR (glued –in rods), elastic system for windows, parquet: Henkel; Jowat; Collano; Nolax (new 1 C PUR) ➢ EPI (Dynea) ❖ High difference beween the systems and in a system

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

  • 4. Gluing of hardwood (glued

laminated timber)

Parameters for testing gluing properties:

  • EN302-1: tensile shear strength A1≥10N/mm2,

A4 ≥ 6N/mm2, wood failure (mean values)

  • EN302-2: delamination, length of delaminated

bondlines ≤5% Material:

  • Ash wood for glulam, different 1C-PUR, Primer

(based on tenisides from Henkel), gluing under industrial conditions)

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

Factors influencing bonding quality

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

Why we have this problems?

  • hardwood: higher MOE, higher strength, higher swelling in

relation to softwood, different extractivs

  • different strain distribution from bondline into wood

(depending on the adhesive stiffness) stiffness UF>MUF>PRF>PUR

  • penetration from adhesive into cell wall (only PRF), no

penetration PUR, different strain distribution?, swelling from wood by using water based adhesives

  • adhesion properties in wet conditions different ?

(problems with 1C- PUR and MUF under wet conditions melamine and ash wood) low wood failure, priming needed for 1C-PUR

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

Experimental tests

  • step1: tests in the Lab, shear strength (A1-A5)
  • step 2: test different adhesives (EPI, MUF, 1C- PUR producer

1), industrial glulam production, delamination test

  • step 3: test 1C-PUR producer 2 and priming, Areodux A185

as reference (Loctite 1C-PUR systems and Loctite PR 3105) (delamination))

  • step 4: test 1C- PUR with priming (adhesives with low

reactivity, gluing direct after primer aplication) and technological optimization, industrial aplication from adhesive: 180g/m2

  • step 5: small technological optimizations (EMC, lamella

thickness, pressure, waiting time after primer application, primer application in g/m2)

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

Gluing under industrial conditions

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

step 1:

different adhesives (MUF, EPI, 1-PUR (producer 1)

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

step 2:

1C- PUR, producer 2 and priming

PUR with low reactivity (pressing time 12h), 20g/m2 primer (10% concentration), manuell adhesive application

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

step 3:

producer 2, primer concentration and waiting time

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

step 4:

delamination EN 302-2 of ash wood (primer concentration)

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

step 5:

delamination EN 302-2 of ash wood

(PC+ wating time), reduced lamella thickness 25mm and EMC

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences 20

delamination from ash wood

1C PUR with primer, HB 181, 20g/m2 Primer (10%), 10 min. open time + reduced lamella thickness (25mm) without priming HBS 707 with priming

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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

▪ Problems with delamination test (EN 302-2 for

hardwood, only few adhesives fullfill norms (PRF Aerodux A185, special 1C -PUR (low reactivity and with priming, strong difference between adhesives))

▪ Also optimization from technology (EMC, grading

from lamellas, lamella thickness, pressure) important

  • 5. Conclusions
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Berner Fachhochschule | Haute école spécialisée bernoise | Bern University of Applied Sciences

Thank you very much

BFH Biel, 2018