PULL-OUT BEHAVIOUR OF ADHESIVES BONDED STRUCTURAL

CONNECTOR

MOHAMAD MUZAMMIL BIN ZAKARIA

FH 2018 65

PULL-OUT BEHAVIOUR OF ADHESIVES BONDED

STRUCTURAL CONNECTOR

By

MOHAMAD MUZAMMIL BIN ZAKARIA

A Project Report Submitted in Partial Fulfillment of the Requirement for

the Degree of Bachelor of Wood Science Technology

Faculty of Forestry

Universiti Putra Malaysia

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Specially dedicated to my

Parent,

Zakaria Bin Mohd Yunus

&

Norzihan Binti Ismail

Family and friends

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ABSTRACT

Connections for timber structures using concealed bonded-in rods offer one possible solution to the development of more efficient joining methods. However the importance of certain basic joint characteristics, and the influence of adhesive type and properties, are not yet fully understood and as such design criteria are lacking. This paper describes a comprehensive experimental and numerical investigation into the fundamental material and joint geometry characteristics of rods bonded in to timber. The adhesive type and performance are both considered, along with test configuration and joint parameters that included rod and timber species. It was found that epoxy adhesives out-performed all other types investigated, and pull-out strengths can be significantly improved through careful selection and optimization of the joint geometry. Balau sample exhibited higher pull-out strength with a means of 10.43 MPa (τta) and 15.65 MPa (τra). This indicates that the shear

strength values of the tested specimens were affected by the density of wood species although the results indicate a declining value of average shear strength due to the adhesive type. There is a strong correlation between the density of the wood and mean shear strength. Failure mode in softwood and hardwood is mostly related to the anatomical properties of the wood which influences the wettability of adhesive that has been use.

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ABSTRAK

Teknik rod terikat untuk menyambungkan struktur kayu yang tersembunyi menawarkan satu jalan penyelesaian adalah kaedah penyambungan yang lebih cekap. Walau bagaimanapun, kepentingan ciri-ciri bersama asas tertentu, pengaruh seperti jenis dan sifat pelekat, masih belum difahami sepenuhnya dan kriteria reka bentuk sedemikian masih pada jumlah yang kecil. Dengan ini ia memberikan penyiasatan eksperimen yang berangka komprehensif ke dalam bahan asas dan ciri geometri bersama rod yang terikat pada kayu. Jenis ikatan dan prestasi kedua-duanya dipertimbangkan, dengan ujian konfigurasi dan parameter berserta dengan jenis rod dan kayu. Melaui ini didapati bahawa pelekat epoksi dan dikaji ke atas semua jenis dan kekuatan tarik keluar dapat dipertingkatkan dengan ketara melalui pemilihan dan pengoptimalan geometri. Sampel Balau mempamerkan kekuatan Tarik yang tinggi dengan nilai 10.43 MPa (τta) dan 15.65 MPa (τra). Ini

menunjukkan bahawa nilai kekuatan spesimen yang diuji telah dipengaruhi oleh ketumpatan spesies kayu walaupun hasilnya menunjukkan penurunan nilai kekuatan purata geseran disebabkan oleh jenis pelekat. Terdapat persamaan yang kuat antara ketumpatan kayu dan kekuatan geseran. Tahap kegagalan dalam kayu lembut dan kayu keras kebanyakannya berkaitan dengan sifat-sifat anatomi kayu yang mempengaruhi kebolehbenturan pelekat yang telah digunakan.

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ACKNOWLEGMENTS

The author wishes to express her deepest appreciation to his supervisor, Dr

Adlin Sabrina Binti Muhammad Roseley for her guidance, trust, constructive

criticisms, suggestions and her patience on the author throughout research

period. Thank you for all knowledge that had been shared with the author

from the beginning till the end of this research.

Special acknowledgment toward staff of faculty Mr. Mohd Rizal Abd Rahman

and staff of faculty of engineering Mr.Muhammad Wildan Ilyas Mohamed

Ghazali and Mr. Mohd Saiful Azuar Md. Isa for their help in guidance,

support and kindly providing the facilities to the author and group member

along this research.

Finally, the author wishes to express his most sincere appreciation toward

his beloved family, and his friends for their love, encouragement during this

research.

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APPROVAL SHEET

I certify that this research project report entitled “PULL-OUT BEHAVIOUR

OF ADHESIVES BONDED STRUCTURAL CONNECTOR” by Mohamad

Muzammil Bin Zakaria has been examined and approved as a partial

fulfilment of the requirement for the degree of Bachelor of Wood Science and

Technology in the Faculty of Forestry, university Putra Malaysia.

Approval by:

Dr Adlin Sabrina Binti Muhammad Roseley

Faculty of Forestry,

Universiti Putra Malaysia.

(Supervisor)

Professor Dr. Mohamed Zakaria Bin Hussin

Dean

Faculty of Forestry

Universiti Putra Malaysia

Date: January 2018

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TABLE OF CONTENTS

Contents Pages

DEDICATION i

ABSTRACT ii

ABSTRAK iii

ACKNOWLEDGEMENT iv

APPROVAL SHEET v

LIST OF TABLES viii

LIST OF FIGURES ix

LIST OF ABBREVIATIONS xi

Chapter 1: Introduction

1.1 Background of study 1

1.2 Problem statement and justification 4

1.3 Objective 5

Chapter 2: Literature review

2.1 Introduction 6

2.2 Overview of timber structure connections 6

2.3 Bonded-in connection in structural construction 10

2.4 Types of structural adhesives 12

2.4.1 Epoxy 14

2.4.2 Polyurethanes. 15 2.4.3 Phenol-resorcinol-formaldehyde. 16

Chapter 3: Methodology

3.1 Material

3.1.1 Structural adhesives 17

3.1.2 Type of wood and rod 17

3.2 Sample preparation 19

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3.3 Equipment and test configuration

3.3.1 Pull-out testing 22

3.4 Evaluation and analysis 23

Chapter 4: Result and Discussion

4.1 Effect of adhesive type on shear strength 25

4.2 Effect of wood types on shear strength 30

4.3 The interaction between adhesive and density 34

Chapter 5: Conclusion and Recommendation 37

References 39

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LIST OF TABLES

Table Page

Table 1: Types of Adhesive Resin Options Most Commonly Used In the Connection Bonded-In Rod and the Repair of Timber.

13

Table 2: Physical and Mechanical Properties of Adhesives. 17

Table 3: Physical and Mechanical Properties of Wood. 18

Table 4: Physical and Mechanical Properties of Rods. 18

Table 5: ANOVA of shear strength for pull-out test of main adhesives.

28

Table 6: Data of mean pull-out force and mean shear strength for epoxy bonded using various types of wood.

32

Table 7: ANOVA of shear strength at timber-adhesive and rod- adhesive interfaces for rods bonded-in.

33

Table 8: Distribution of failure mode for two wood types. 34

Table 9 Tests of Between-Subjects Effects. 35

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LIST OF FIGURES

Figure Page

Figure 1: A conceptual timber frame building, illustrating a variety of concealed connection systems.

7

Figure 2: Example of structure that using mechanical joint and adhesive joint.

9

Figure 3: The example of connection bonded-in rods, 3(a) steels rod bonded-in 3(b) fiber reinforced plastic rod bonded-in.

10

Figure 4: The sample (a) wood block cutting (b) centre hole drilling(c) rod insertion into adhesive-filled hole.

19

Figure 5: Sample dimension of wood block, rod and ‘o’ ring. 20

Figure 6: Threaded steel rods bonded into different wood block with different adhesives.

21

Figure 7: Test configuration of static pull-out test conducted at room temperature.

22

Figure 8: Global slip between the rod and timber. 23

Figure 9: The effect of adhesive type on average maximum load. 25

Figure 10: Mean shear strength timber-adhesive of samples bonded using various types of wood.

26

Figure 11: Mean shear strength rod-adhesive of samples bonded using various types of wood.

26

Figure 12: Adhesive bonded using GFRP rod to show the glue line. 29

Figure 13: Failure area for (a) Epoxy (b) PU (c) PRF. 29

Figure 14: Mean maximum load of samples bonded using various types of wood.

30

Figure 15: Mean shear strength timber-adhesive of samples bonded using various types of wood.

31

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Figure 16: Mean shear strength rod-adhesive of samples bonded using various types of wood.

31

Figure 17: A composition on types of failure modes for Balau wood. 33

Figure 18: The interaction between adhesive and density. 35

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LIST OF ABBREVIATIONS

CFRP Carbon fiber-reinforcement plastic

GFRP Glass fiber reinforcement plastic

PU Polyurethanes

PRF Phenol-resorcinol formaldehyde

EPX Epoxy

RH Relative humidity

LVL Laminated veneer lumber

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CHAPTER 1

INTRODUCTION

1.1 Background of Study

Structural timber has undergone a technological revival in terms of its

application and processing in recent years. This has been largely a result of

rising industry costs and ever increasing environmental awareness,

encouraging more efficient utilization of home grown timber resources.

These have produced efficient structural composite lumber (SCL) materials

such as laminated veneer lumber (LVL), laminated strand lumber (LSL) and

parallel strand lumber (PSL) other forms of composite timber such as glulam

are also experiencing a revived interest (Broughton and Hutchinson, 2001b).

Prefabricated connection systems offer several potential advantages over

traditional connection methods, in terms of both the appearance and the

strength of the connection. Furthermore, factory-made jointing arrangements

of a hidden nature have the potential to give close control over quality of

manufacture. It is clear that, as the structural capabilities of modern timber

products become more widely realized high-performance connection

systems must be available to facilitate the exploitation of these materials.

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The use of traditional connections such as bolts and nails in conjunction with

steel plates in an exposed fashion can result in very unsightly, bulky and

inefficient connections in larger structures. The appearance can destroy the

elegance of the chosen structural form. Concealment, on the other hand, not

only offers aesthetic benefits, but also brings other advantages, including

resistance against environmental degradation and fire. Concealed

connection method, also generally provide a wider scope for employment of

prefabrication, thus providing the opportunity for closer control over

manufacture and resultant quality (Bainbridge and Mettem, 1998).

As identified through a recent review of innovative and improved connection

methods, the use of bonded-in rods is an important feature of many of the

timber engineering techniques for connections using adhesives (Bainbridge

et al., 2002). Adhesive bonding technology has been studied for many years

and it has played an essential role in the development and growth of the

rehabilitation and repairing techniques of timber structures involving

adhesive joints instead of mechanical joints. The widespread use of adhesive

bonding can be attributed to its inherent advantages, such as, the fact that

an adhesive joint can distribute the applied load over the entire bonded area

and with a more uniform distribution of stress, it requires little or no damage

to the adherents, adds very little weight to the structure, has a superior

fatigue resistance to other joining methods, is suitable for joining dissimilar

materials, and can reduce manufacturing costs (Custodio et al., 2009).

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Such as specific adhesion practical applications on site generally utilize

epoxy, polyurethane adhesives and additionally some polyester products for

structural bonding applications on timber. Of these varieties, epoxy

adhesives have been used for more than forty years and they are currently

still the most widely used choice for bonding structural timber on site. Epoxy

types intended to be used for site bonding of timber components implies that

in practice they have to be able to cure at moderately low temperatures.

These are required for practical reasons to include good gap-filling shrink

resistant properties, excellent tensile/shear strength, high dry and wet

strength, and good resistance against moisture and certain chemicals.

Another class of adhesive products commonly used for interventions on site

is two-component polyurethanes. In contrast, monocomponent

polyurethanes, although largely used in manufacturing plants to construct

glulam components, are not, in general, preferred for applications on site

owing to their tendency to develop gas bubbles within the thick glue line, thus

compromising the cohesive strength of the bonded components.

Phenol–resorcinol based (PRF) adhesives were occasionally used to repair

timber on site, for instance to bond glued-in rods or to glue side plates for

beam reinforcement. Although these applications have not been widely used

they are mentioned in order to present a complete picture (Pizzo and

Smedley, 2015).

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The nature of wood surfaces is difficult to control nearby as opposed to what

might be experienced in an assembling plant, specifically where there is

successful control of the surfaces to be fortified. Frequently the surfaces are

newly machined by sanding or planing in a perfect domain with the right

temperature and dampness, which empowers the dampness substance of

the wood surfaces to be controlled and encourages a decent holding surface.

This is as opposed to the conditions nearby where the majority of the above

elements might be variable as well as not effortlessly controllable.

1.2 Problem Statement and Justification

A variety of adhesives have been tested to glue in rods. In early years,

traditional wood adhesives based on phenol-resorcinol (PRF) or epoxies

(EPX) were used, while later work has included also the use of

polyurethanes (PUR). In experiments conducted within a large European

research project in the late 1990s, (GIROD), three types of adhesives were

used suggested namely, PRF, EPX and PUR.

Characterizing an adhesive only by terms like EPX or PUR is nonsufficient.

There are many adhesives available of each type and them ‘‘can show all

types of constitutive behavior’’ (Steiger et. al, 2007). The pull-out strength of

the Glued-in rod is obviously related to the adhesive type, but also to the

used wood species, since different adherents may develop different bonding

strength with different adhesives.

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Generally speaking, and to a varying degree depending on the specific

adhesive used, bond strength can be affected by shrinkage during initial

hardening, by the adhesive’s sensitivity to elevated temperatures, by its

limited gap-filling qualities and by the sensitivity to moisture content changes

due to changes in local climatic conditions.

These effects have to be taken into account in design. According to MS544

part 5 in timber joint there are no data on glued-in rod connection for

Malaysia timber. Because of that, this research has been conduct to study

the use of different adhesive in glue-in rod to Malaysia timber at local climatic

temperature.

1.3 Objectives

The objective of this research is to investigate the relationship between the

adhesive and local climatic conditions toward Malaysia timber. In order to

achieve the objective, the following specific objective required to be fulfilled.

1. To determine the shear strength of glued-in rod connection using

Malaysian timber.

2. To evaluate the failure modes of bonded-in connections a function

of various type of structural adhesives.

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REFERENCES

Ansell, P., & Smedley, D. (2007). Briefing: Bonded-in technology for structural timber. Construction Materials 160, 95-98.

Bainbridge, R. & Mettem, C. (1998). A review of moment-resistant structural timber connection. Structural and building 128, 323-331.

Bainbridge, R., Mettem, C., Harvey, K., & Ansell, M. (2002). Bonded-in rod connections for timber structures development of design methods and test observations. International Journal of Adhesion & Adhesives, 47-59.

Broughton, J. G., & Hutchinson, A. (2001a). Effect of timber moisture content on bonded-in rods. Construction and Building Materials 15, 17-25.

Broughton, J. G., & Hutchinson, A. (2001b). Pull-out behaviour of steel rods bonded into timber. Materials and Structures 34, 100-109.

Broughton, J. G., & Hutchinson, A. (2001c). Adhesive systems for structural connections in timber. International Journal of Adhesion & Adhesives 21, 177-186.

Broughton, J. G., & Hutchinson, A. (2003). Review of relevant materials and their requirements for timber repair and restoration. LICONS (low intrusion

conservation systems for timber structures, CRAF-1999-71216, Task 2.2.

Claisse, A., Davis, J., & Masse, B. (2007). Fatigue testing of glass/epoxy joints in timber up to the endurance limit. Construction and Building Materials

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Colak, A. (2001). Parametric study of factors affecting the pull-out strength of steel rods bonded into precast concrete panels. International Journal of

Adhesion & Adhesives 21, 487-493.

Custodio, J., Broughton, J. G., & Cruz, H. (2009). A review of factors influencing the durability of structural bonded. International Journal of

Adhesion & Adhesives 29, 173-185.

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