MTS Adhesives Project 5 5/P5r8.pdf · This report contributes to Project 5 of the programme on adhesives supported by the DTI through the Measurement Technology and Standards (MTS)

MTS Adhesives Project 5

Measurements For Optimizing Adhesives Processing

Task 2 Optimisation of Key Process Parameters

Report 8

Case Study: Steel Plate Bonding

S Hurley P.A. J Gibbs

Taywood Engineering

This report forms part of the deliverable for Task 2

Reports for Task 2

Report 2; Optimisation of Key Process Parameters - Summary Report Report 3; Case Study: Precision Mechanical Assembly in the Business Machines Industry Report 4; Case Study: Packaging Applications 1 &2: Summary Report Report 5; Case Study Packaging Application 1: Full Report Report 6; Case Study: Packaging Application 2: Full Report Report 7; Case Study: Access Flooring Application Report 8; Case Study: Construction Application - Steel Plate Bonding Report 9; Optimisation of Key Process Parameters - Draft Code of Best Practice

1

Technical Report

Title

& Date of Issue

Report No. 1303S/96/9318

Page 1 of 45

Measurements For Optimizing Adhesive

Processing

A Statistical Approach for Determining the

Factors Affecting Bond Strength

Dr A Olusanya, National Physical Laboratory (2 copies) S A Hurley Author (2 copies)

Abstract This report contributes to Project 5 of the programme on adhesives supported by the DTI through the

Measurement Technology and Standards (MTS) budget. This project is led by the National Physical Laboratory.

This report presents experimental data and a Taguchi approach of experimental design to determine important processing variables likely to influence the development of bond strength in construction related steel plate bonding applications.

This report is copyright. Reproduction of the whole or any part thereof must not be made without the express permission of Taywood Engineering Limited. This report and the results shown and any recommendations or advice made herein are based upon the information, drawings, samples and tests referred to in the report Taywood Engineering Limited accepts no liability for any damages, charges, costs (including, but not limited to, legal rests) or expanses in respect of or in relation to any damage to any property or other loss (save for death or personal injury occasioned by reason of any negligence on the part of Taywood Engineering Limited) whatsoever arising either directly or indirectly from the use of the report, the carrying out of any recommendations contained

Taywood Engineering Ltd Technology Division

—

Taywood House. 345 Ruislip Road . Southall . Middlesex. UB1 2QX Issue 4 / 4482 / December 1994

Taywood Engineering Limited Report No. 1303S/96/93 18

Page 2 of 45

CONTENTS

SUMMARY

1.

2.

3.

4.

5.

6.

7.

INTRODUCTION

OBJECTIVES

METHODOLOGY

3.1 Application

3.2 Site Study

3.3 Bonding Process

3.4 Process Variables

EXPERIMENTAL

4.1 Bond Quality Assessment

4.2 Adhesive

4.3 Process Variables

4.3.1 Steel Substrate

4.3.2 Concrete Substrate

4.4 Experiment Design

RESULTS

5.1 Steel Substrate

5.2 Concrete Substrate

CONFIRMATORY TRIAL

CONCLUSIONS

ACKNOWLEDGEMENTS

Figures 1-2

Tables 1-6

Plates 1-5

Appendix 1

Appendix 2


Page 3 of 45

SUMMARY

The work reported here forms part of a project concerned with the optimisation of adhesive

processing led by the National Physical Laboratory and, thereby, contributes to a wider ranging

research programme on adhesives funded by the DTI.

The main objective of this work was to assess the benefits of applying Taguchi statistical

methods to an evaluation of the key processing variables associated with a construction based

application of adhesives. The bonding of steel plate reinforcement to concrete and cast iron

structures with a two-part cold curing epoxy resin was selected as a representative application.

Following a site visit ten variables, each of which could influence bond strength were

identified for investigation. These included adhesive grade (fast/slow curing) and aspects of

substrate surface condition, adhesive application and cure. In conjunction with Xyratex

Limited, Taguchi methods were then used to define an array of 16 experiments which would

allow the significance of each variable to be evaluated at two levels for a given substrate (the

equivalent array given by a full factorial approach would require 1024 experiments).

Laboratory-based tensile pull-off tests were used, with a replication level of 5, to determine the

effects of the 16 selected conditions on bond strength. Both concrete and steel substrates were

investigated. The results of these tests were analysed with Xyratex Limited using Taguchi

statistical procedures.

Due to the scatter in results and the limitation on failure stress resulting from the inherently

low tensile strength of concrete, it was not possible to rank the variables for this substrate.

However, for steel, bond strength was found to be significantly affected by 5 variables;

additionally, 3 significant interactions were revealed, each of which involved the adhesive

grade.

The Taguchi analysis also predicted

the optimum processing conditions.

satisfactorily with this prediction.

the bond strength which should be achieved on steel under I

A further set of 10 pull-off tests gave results which agreed

It was concluded that, for this type of application, valuable information can be obtained from

minimal testing using the Taguchi approach to the design of experiments.

Taywood Engineering Limited Report No. 1303S/96/9318

Page 4 of 45

1. INTRODUCTION

This report contributes to Project 5 of the 1993-95 programme on adhesives supported by the

DTI through the Measurement Technology and Standards (MTS) budget. This project is led

by the National Physical Laboratory (Division of Materials Metrology) and is concerned with

measurements for optimizing adhesive processing.

The rationale for this project is based on the view, supported by an earlier and wide-ranging

survey, that the confident use of adhesives in many industrial sectors may be increased and

made more profitable by addressing two particular areas (amongst others) viz:

(i) the validation of quantitative methods which can be used in the manufacturing

environment to measure and rank properties which are associated with processing, for

example: viscosity, slump, tack, open time and cure.

(ii) the development of a methodology which can be used to define and evaluate the key

aspects of a process, thus enabling methods of control to be implemented effectively.

The second area is important because many seemingly simple industrial processes which utilise

adhesives do, in fact, depend upon complex and possibly synergistic interactions.

Consequently, reliable and relatively rapid methods of quantitatively distinguishing the

influential parameters could lead to greater cost-effectiveness.

As sub-contractors to NPL, part of Taywood Engineering’s role in Project 5 was to address

this second area in the context of the construction industry (Project Tasks (T)3c.5-(T)3c.6).

More specifically, TEL were requested to investigate the processing of typical adhesives used

in civil engineering applications. This work was carried out in conjunction with Xyratex Ltd

(formerly IBM, Havant) where a Design of Experiments philosophy that incorporates

‘Taguchi’ experimental methods has been widely used for quality improvements and process

optimisation of adhesive bonding operations. I

The well-established technique of bonding steel plate reinforcement to concrete and cast iron

structures was used as a model application for this work. This process relies upon the

structural performance of an adhesive which is commonly applied in external conditions. In the

present study, therefore, it may be considered also to represent other applications which place

similar demands upon adhesive use.


Page 5 of 45

2. OBJECTIVES

A large number of process variables and their possible synergistic interactions can affect the quality of

adhesive bonding in civil engineering applications. consequently, through an understanding of the

important variables and their relative interactions, methodologies could be developed to improve the

quality of adhesive bonding performed on-site. the aim of the work described in this report was to

assess taguchi methodologies of experimental design for dete rmining important processing variables

affecting the quality of adhesive joints

structures for experimentation, small

processing variables.

used in civil engineering. due to the obvious unavailability of real

scale laboratory tests were utilised to determine the important

3. METHODOLOGY

3.1 APPLICATION

The bonding of external steel plate reinforcement to concrete and cast iron structures was

considered to be a suitable civil engineering application for investigation with the Taguchi

methodology of experimental design. Due to the obvious inability to experiment with real

strengthening operations, small scale laboratory specimens were used to investigate a number

of variables likely to affect bond quality. To aid identification of these processing variables, a

site visit was carried out prior to the Taguchi experimental design.

3.2 SITE STUDY

The bonding of steel plate reinforcement to the soffits of three canal bridges running under

Grosvenor Road, Embankment, London, was chosen as a suitably complex operation for

determining g the variables likely to influence bond quality. The site visit was conducted with

representatives from Sika Ltd (adhesive manufacturer), Taywood Engineering, NPL and I

Xyratex, thus enabling the important processing variables to be discussed in detail.

The Grosvenor Road operation was particularly complex due to the tidal rise and fall of the

River Thames, (Plates 1 and 2). Bonding works were only possible during low tide when the

soffit became accessible. At high tide, the scaffolding platform became covered, leaving a gap

between the bridge soffit and water level of approximately lm. Due to this low clearance,

water would occasionally splash onto prepared surfaces (Plate 3). This was likely to effect

bond quality significantly and was to form an important process variable in the experimental

work.


Page 6 of 45

3.3 BONDING PROCESS

The bonding process, as summarised in Figure 1, involved the following three important

stages:

. Preparation of the steel plate reinforcement.

. Preparation of the bridge soffit.

. Mixing and application of the adhesive.

To reduce on-site preparation problems, the steel plates were pre-treated prior to delivery.

The plates were pre-treated on all faces in the following manner:

● degreased

. dry blasted

. vacuum cleaned

● primed with a micaceous iron oxide based paint

. packed with a desiccant.

On site, the bridge soffit was treated in the following manner:

. degreased

. dry blasted

. vacuum cleaned

Additionally, where excessive roughness and pitting of the soffit existed, a thin coat of the

adhesive was applied to smooth the bond surface.

The two part epoxy adhesive, Sikadur 31 PBA (plate bonding adhesive) was supplied to site in

premeasured packs. To minimise mixing problems, the base resin component was supplied in

the colour white, with the amine hardener supplied in the colour black. These colours

provided a simple visual indication of any mixing inconsistencies.

Mixing of the Sikadur 31PBA was achieved by scrapping the contents of the premeasured

hardener pack into the preweighed resin pack and mixing for approximately 2-3 minutes with a

drill. The mixing process was continued until a uniform colour was achieved, indicating

adequate mixing. Following mixing, the adhesive was allowed to stand for 10 minutes whilst

the steel plate reinforcement was unpacked and given a final decreasing. The adhesive was

trowel applied to the soffit of the bridge deck to give a uniform layer lmm in thickness (Plate

4), and to the plates with a profiled thickness ranging from 3mm at the centre to lmm at the

edges.


Page 7 of 45

Bonding was achieved by jacking the plates upwards and locating predrilled holes in the steel

plate reinforcement on anti-peel bolts fixed to the bridge soffit. The bonded joint was

completed by further jacking and tightening of the anti-peel bolts (which held spacer washers

to achieve a consistent 2mm bond-line thickness).

Following cure of the adhesive, the bond was checked for voids by hammer tapping. Any

voids were filled by drilling through the steel plate and injecting additional adhesive.

Finally, the bonded plates and edges of the adhesive joint were treated with a high build paint system to provide long-term environmental protection (Plate 5).

3.4 PROCESS VARIABLES

Discussions were held immediately after the site visit to determine the process variables likely

to affect bond strength. As a result, the following important variables were identified for

investigation:

●

●

●

●

●

●

●

●

●

●

Adhesive type.

Mixing ratio of the resin and hardener.

Workability and compaction of the adhesive.

Moisture contamination of the substrates prior to bonding.

Effectiveness of solvent cleaning.

Effectiveness of vacuum cleaning.

Humidity during mixing and adhesive application. ,

Open time of the joint before closure.

Cure temperature.

Cure time.


Page 8 of 45

4. EXPERIMENTAL

4.1 BOND QUALITY ASSESSMENT

Tensile pull-off tests were conducted in the laboratory using 20mm diameter dollies to

investigate the effects of the identified variables on bond strength. Two separate experiments

were devised to examine adhesion on concrete and mild steel substrates.

The pull-off test was considered to be a suitable technique for examining bond quality by

measuring variations in bond strength. The particular advantage of this test over other

potential methods is that it gives a relatively simple procedure that minimises the inclusion of

additional variables during joint manufacture. A standard portable pull-off tester was used in

the Taguchi test programme. This equipment (the ‘Limpet’), enables a maximum tensile load

of 10kN to be applied. Due to this limit, a 20mm diameter dolly was used for the tests. This

enables testing to be performed with an adhesive achieving an ultimate tensile/bond strength in

excess of 30 MPa on a steel substrate.

Both steel and concrete substrates were used to simulate the bridge soffit. A steel thickness of

10mm was chosen to minimise deflection during testing. In addition, the steel substrate was

grit blasted to an SA2½ finish (as specified in I SO 8501-01) controlled to give a peak to

trough surface roughness of 50- 10Opm. Concrete substrates were prepared in accordance with

the draft CEN standard EN 104-801-1 to the mix grade MC (0,40). The draft standard was

followed with the exception of clause 5.1 requiring aggregates with a water absorption of less

than 2%. The aggregate used was Thames Valley 5- 10mm with a water absorption of 3 .5°A

which was considered to have a negligible effect on the quality of the concrete. This clause

was not followed due to the difficulty in sourcing UK aggregates which comply.

4.2 ADHESIVE

Sikadur 31 Plate Bonding Adhesive (PBA), manufactured by SIKA Ltd., was chosen as a

suitable material for the Taguchi task. This material is produced in two grades, ‘Normal’ and

‘Rapid’, both of which are filled cold-curing two-part epoxy resin adhesives. Both products

have similar properties, with the rapid grade formulated for lower temperature applications

(down to a minimum of 5C).

Sikadur 3lPBA was specifically formulated for the bonding of external plate reinforcement for

the structural strengthening/stiffening of concrete and steel structures. This adhesive system

has a proven history within the construction industry, as does the methodology adopted for the

bonding process.


Page 9 of 45

4.3

4.3.1

Since the early 1980s, extensive testing has been carried out on Sikadur 3lPBA and some

typical properties for the fully cured ‘Normal Grade’ tested at 23°C are shown below:

Density (g/cm3) 1.5

Young’s Modulus (GPa) 7

Tensile Strength (MPa) 22

Compressive Strength (MPa) 70

Fracture Energy (kJm-2) 0.4

Poisson’s Ratio 0.3

Strain to Failure (%) 0.7

PROCESS VARIABLES

Steel Substrate

The following ten process variables were investigated at the two settings shown below:

Variables Setting 1 Setting 2

Adhesive Type Normal Grade Low Temperature Grade

Adhesive Application Levelled over Surface Applied as Blob

Resin to Hardener Mix Ratio Specified Ratio Minus 10% of Hardener

Mix Humidity 10% Humidity 70% Humidity

Open Time to Joint Closure Minimum Possible Recommended Maximum +1O%

Cure Temperature 23°C Recommended Minimum -5°C

Decreasing of Steel No Solvent Clean Solvent Clean

Vacuum Cleaning of Steel No Vacuum Clean Vacuum Cleaned

Cure Time to Test 1 day 2 days

Steel Surface Condition Wet Dry

Note: Actual test conditions combine elements of setting 1 and 2.

Taywood Engineering Limited Report No. 1303S196/9318

Page 10 of 45

4.3.2

4.4

Concrete Substrate

The concrete substrate experiment was designed to be as close to that with the steel substrate

as possible, hence a 20mm diameter dolly was used on both substrates; for concrete testing, a

50mm dolly is preferable and commonly but not universally used. The identical variables were

used except that the concrete surface condition varied from dry to damp.

EXPERIMENT DESIGN

A full factorial experiment covering ten variables set at two levels would require 1024 separate

runs (i.e. 210). This type of design is therefore impractical on a cost and time basis when

considering the even larger number of variables that may need to be addressed in some

construction related applications. Using the Taguchi approach to experimental design, it was

possible to reduce the total number of experiments to 16, as shown in Figure 2. This design of

experiment approach enabled each of the main variables to be assessed. Experimental arrays

for the Taguchi analysis were determined by Xyratex. Two separate arrays for the steel and

concrete substrates were developed and are shown in Tables 1 and 2 respectively.

However, due to the large number of variables, each main factor had a possible alias, or

interaction of other variables that could shadow its effect (Table 3). A larger number of

experiments could have been carried out to avoid the possibility of first order interactions;

however, it was considered impractical to increase the number of experiments beyond 16. A

possible alternative to increasing the number of experiments would have been to reduce the

total number of variables to below 8. However, this approach was not favoured due to the

importance of each chosen variable and its potential for having a large effect on bond strength.

It was therefore decided to examine the ten variables, with a 16 experiment array, and use

engineering judgement to determine whether further experimentation should be carried out to

deconvolute problems with aliases.

For each of the 16 experiments, five repeat runs were carried out. Five runs were considered

to be sufficient to detect changes of less than 10%, assuming a variability in runs of

approximately ± 15%.


Page 11 of 45

5. RESULTS

5.1 STEEL SUBSTRATE

Results for the steel pull-off tests are shown in Table 4. This data was generally consistent,

with scatter between tests averaging around 15%. The box whisker plot (Figure 2) shows

variability in a clearer graphical form described with the following key: small circle

representing the mean whiskers representing maximum and minimum scatter; top horizontal

line of the box representing the 75th percentile; bottom horizontal line representing the 25th

percentile; and the middle line representing the 50th percentile.

Details of the Taguchi analysis for the steel substrate are given in Appendix 2. The Taguchi

software was able to reasonably explain 68% of all variability in results with the calculated

factors, as indicated by the R-squared value of 0.68 shown in the table of coefficients.

Analysis of the coefficients revealed that the most significant variables influencing bond quality

are:

● Adhesive type.

● Humidity during mixing.

. Time to test after joint closure (i.e., cure time).

. Vacuum cleaning the adherends prior to bonding.

Graphical representations of the effects of each variable on bond strength are shown in the

variable response plot given in Appendix 2. This plot represents the response of the mean

bond strength for each variable and its setting. For example, for variable A (adhesive type)

point Al represents the low temperature adhesive and A2 represents the normal grade; as

shown, the low temperature grade results in a greater bond strength for the experimental

conditions investigated. The upper and lower horizontal lines of the graph represent

boundaries within which there are no significant differences. Significant factors that result in

an increase in bond strength were found to be:

. The low temperature grade provides a higher bond strength than the normal adhesive.

● Storing and mixing the adhesive at a high humidity results in a lower bond strength.

. Solvent cleaning the steel prior to bonding results in a lower bond strength.

. Vacuum cleaning the steel adherends prior to bonding results in a higher bond strength.

● A cure time of 1 day resulted in a significantly higher bond strength than for a 2 day cure

period.


Page 12 of 45

As previously discussed, each imposed variable has a number of possible aliases which could

represent the main variable. A table of coefficients representing each of the possible first order

interactions and aliases is given in Appendix 2. It was decided that first order interactions

representing each of the main process variables were unlikely and further experimentation to

confirm this assumption could not be justified.

From the table of coefficients for aliases and first order interactions, three significant

interactions were identified:

● Adhesive type and humidity.

● Adhesive type and cure temperature.

. Adhesive type and joint open time.

AU significant interactions involved adhesive type. Furthermore, the interacting variables are

known to affect the performance of two-part cold-curing epoxy adhesives. Consequently, the

significant first order interactions were not unexpected.

5.2 CONCRETE SUBSTRATE

Results for the concrete pull-off tests are shown in Table 5. A large scatter was observed

which was attributed to the variability of the concrete substrate, the unsuitable ratio of

aggregate to dolly diameter, and the decision not to core the concrete surrounding the dolly

prior to testing.

The tensile pull-off strength of the standard MC (0,40) concrete ranged from 3.1 to 7.7 MPa

with an average strength of 5.3 MPa. The draft CEN standard states that an average pull-off

strength of 3.5 MPa should be achieved, with a minimum of 3.0 MPa, when tests are carried

out in accordance with the draft CEN Standard EN 104-846. Test data obtained here showed

a higher strength than that described in the draft standard, but this may be attributed to

differences in the test procedure. Pull-off testing for the Taguchi task was deliberately carried

out without coring the concrete surrounding the test dolly. Without coring, higher strength is

expected due to the different failure mode initiated in the concrete. Coring was omitted since

the higher failure loads would be more likely to show processing problems due to variations in

the surface preparation.


Page 13 of 45

Results for the Taguchi analysis on the concrete substrate are given in Appendix 1. The

analysis failed to show significant effects for any of the experimental variables due to the large

scatter in results. This is shown in the variable response plot where significant effects fall

inside the upper and lower scatter limits marked on the graph. Additionally, the table of

coefficients for the Taguchi analysis, (Page 31), shows an R-squared value of only 0.32,

indicating that only 32°/0 of all variability is explained by the calculated analysis factors.

Due to the scatter in results, the Taguchi experiment was unable to detect significant effects

likely to influence bond quality for a concrete substrate. The Taguchi methodology was

therefore considered to be unsuitable for the concrete substrate test conditions investigated.

.- Taywood Engineering Limited Report No. 1303S/96/9318

Page 14 of 45

6. CONFIRMATORY TRIAL

The Taguchi analysis identified the significant process variables to be:

. Adhesive type.

. Vacuum cleaning of steel substrate.

. Solvent cleaning of steel substrate.

. Relative humidity.

. Cure time.

The optimum process conditions for a maximum bond strength were identified as:

. Low temperature grade adhesive.

. 10% relative humidity.

. Vacuum cleaning of steel substrate.

. 24h cure time.

. No solvent cleaning of the steel.

Ten test specimens were prepared using the above conditions and the following prediction of

the results was calculated with the Taguchi software: a bond strength of 23.49 MPa ±

1.69 MPa to a confidence level of 90% assuming a run of 7 test samples.

Results from the confirmatory trial are shown in Table 6. Sample numbers 7, 10 and 11 were

omitted from the calculation of mean bond strength due to large defects at the edge of the

obtained.

The Taguchi calculation of bond strength agreed with the experimental data although the latter

was at the lower limit of the predicted value. This might be explained by a slight change in the

material used in the confirmatory trial which was supplied as Sikadur 31 and not Sikadur 31

PBA - although identical properties would be expected (a’ slight difference in coloration was

noted between the materials). However, despite this difference, the predicted result agreed

closely with that given by the confirmatory trial.


Page 15 of 45

7 CONCLUSIONS

The Taguchi analysis for the concrete substrate was inconclusive. Problems arose due to

scatter in the test data which maybe attributed to the following factors:

. Variability y of the concrete substrate.

. Unsuitable aggregate to dolly diameter ratio.

. Omitting coring of the concrete at the base of the test dolly prior to carrying out the pull-off

test.

A larger diameter test dolly combined with coring of the concrete would possibly have reduced

scatter in the pull-off test data. However, it is unlikely that additional information would have

been obtained from the experimental variables investigated due to the inherently low tensile

strength of the concrete substrate. All of the test conditions investigated resulted

predominantly in concrete cohesive failure and, therefore, in similar tensile strengths being

obtained. It was therefore concluded that, as changes in surface treatment did not give bond

strengths below the tensile strength of the concrete, little advantage would have been obtained

with a more refined test procedure to reduce scatter. The inherently low tensile strength of

concrete presents a general problem in adhesion testing as, for other than very low bond

strengths, substrate cohesive failure commonly dominates. However, until bond testing is

performed, it is usually not possible to predict confidently that this will occur.

During the manufacture of specimens for the Taguchi experiment, it was found difficult to

produce the standard concrete specified in the draft CEN standard EN 104-801-1. Difficulties

arose in the sourcing of UK aggregates able to comply with this standard. Since the present

work commenced, this problem has been communicated to and addressed by the appropriate

BSI committee.

The Taguchi analysis on the steel substrate successfully indicated important factors likely to

influence bond strength when using Sikadur31 PBA.

Furthermore, the analysis also showed that certain factors, expected to influence bond strength

significantly, had little effect. These factors were:

●

●

●

Dampness of the adherends prior to bonding (note: in the laboratory experiment water was

added shortly before closing the joint).

Small differences in the mix ratio of hardener to resin

Open time before joint closure


Page 16 of 45

It must be emphasised that the significance of variables found in this

particular product; other epoxy based adhesives may perform quite

qualification does not detract from the value of the work as the main intent

Taguchi methodology.

work applies to a

differently. This

was to examine the

A surprising result from the Taguchi experiment was that the shorter cure time resulted in a

higher bond strength. This suggests a possible change from ductile to brittle failure with a

higher level of cross-link density. Such a change could lead to failures being initiated at

defects, for example entrapped air bubbles in the adhesive bond-line.

Vacuum cleaning the steel substrate prior to bonding resulted in an increase in bond strength.

However, further surface preparation using a decreasing solvent resulted in a lowering of bond

strength.

spreading

This result was unexpected and may indicate solvent retention at the surface or the

(rather than removal) of small traces of contamination.


Page 17 of 45

ACKNOWLEDGEMENTS

The work in this report was funded by the Department of Trade and Industry as part of the

Measurements Technology and Standards (MTS) Adhesives Project 5, ‘Measurements for

Optimizing Adhesive Processing’. This work was sub contracted to Taywood Engineering by

the National Physical Laboratory (NPL), the managers for Project 5.


Page 18 of 45

Figure 1 Flow Diagram of the Steel Plate Bonding Process

I Fix anti-peel bolts and spacers

Join and tighten bolts

Cure

Remove loading jacks

Apply surface coatings

.

Taywood Engineering Limited Report No. 1303S/9619318

Page 19 of 45 .

Figure 2 Box Whisker Plots for the Concrete and Steel Substrate Taguchi Analysis Data

TAYWOOD ENGINEERING

●

CONCRETE

RUN NUMBER

.


Page 20 of 45

*,

RUN

6 7

BLOB AREA BLOB BLOB


Page 21 of 45

-.. .

Table 2

RUN

STAN STAN STAN STAN STAN STAN STAN

Experimental Array for the Concrete Substrate.


Page 22 of 45

A B`


Page 23 of 45

Table 4 Taguchi Analysis Pull-Off Test Results for Steel.


Page 24 of 45

Table 5 Taguchi Analysis Pull-Off Test Results for Concrete.


Page 25 of 45

Table 6 Pull-Off Test Results for the Confirmatory Trial on the Steel Substrate.

Dolly Number Force to Failure

(kN)

1 6.65

2 7.16

3 6.76

4 6.04

5 7.44

6 6.53

7 4.76

8 6.70

9 7.48

10 4.99

11 4.83

Failure Stress

(MPa)

21.17

22.79

21.52

19.23

23.68

20.79

15.15

21.33

23.81

15.88

15.37

Failure Mode Comments

COH

COH

COH

COH

COH

COH

ADH Poor sample

ADH

COH

ADH Poor sample

ADH Poor sample

Tests 7, 10, 11 are ignored due to poor test samples containing large defects.

Mean results for the confirmatory trial (neglecting points 7, 10, and 11) are:

Tay wood Engineering Limited Report No 1303S

Page

:/96/9318

28 of 45

Plate 5: Completed Joint coated with a High Build PVC/Acrylic Paint System to Provide Long Term Durability (photograph courtesy of Sika Ltd)


Page 29 of 45

Appendix 1

Taguchi Results for the Concrete Substrate

Taywood Engineering Limited Report No. 1303S/96/93 18 .

Page 30 of 45

ANALYSIS OF FACTORIAL

------


Page 31 of 45

I

TABLE OF COEFFICIENTS 1

0.11485 0.066673 0.091125

Total ERROR was used for F tests.


Page 32 of 45

95

90

75

25

10

5

ANALYSIS OF FACTORIAL EXPERIMENT: TAYWOODC

.

..’ .

Taywood Engineering Limited Report No. 1303 S/96193 18

Page 34 of 45 ‘.

TABLE OF COEFFICIENTS

.


Page 35 of 45


95

90

75

5

. . .

. . .

. .

. . . . . . .

. . . . . . . . . . . .

.

. . . . . . . . .

.

. . . . . .

------

. .

:

0.4 1

*

. . . . . . . .

. . .

. . . . . .

.

. . . . . .

. . . . . . .

.

. . . . . . . . . . . .

.

.-

.

Taywood Engineering Limited Report No. 1303 S/96/93 18 ●

Page 36 of 45


1 ,

—

.


Page 37 of 45

Appendix 2

Taguchi Results for the Steel Substrate


page 38 of 45

o.

ANALYSIS

0.44402 46.33

OF VARIANCE

0.44402 46.33

119.9 119.9 97.511 1.4132 67.718 13.544 29.793 0.46552

304.5 3.8544

F

29.093

Total ERROR was used for F tests.


Page 39 of 45

i

. --

. . . . . .

--


Page 40 of 45

95

90

75

10


Page 41 of 45

ANALYSIS OF FACTORIAL DENSITY FUNCTION

EXPERIMENT: TAYWOODS

RESIDUAL


Page 42 of 45

. . . TABLE OF COEFFICIENTS

16 OBSERVATIONS R-SQUARED = 0.9239 11 VARIABLES

STANDARD ERROR = 0.36714 ADJ R-SQUARED = 0.77169

`0.18357 0.18357 0.18357 0.18357 0.18357 0.18357 0.18357

SIG LEVEL 0.00032835 0.023192 0.56038 0.060087 0.25607 0.021818 0.023296 0.96826 0.056145 0.13587 0.018341

0.

0.12042 1.0642

ITS

7

-. ,

Taywood Engineering Limited Report No. 1303 S/96/93 18

Page 43 of 45

90

75

25

0

5

ANALYSIS OF FACTORIAL EXPERIMENT TAYWOODS

–1.0 –0.5 o 0.5 1.0

FACTORIAL EFFECTS 1

.

.—

#

—


Page 45 of 45

t

1

.

MTS Adhesives Project 5 5/P5r8.pdf · This report contributes to Project 5 of the programme on adhesives supported by the DTI through the Measurement Technology and Standards (MTS)

Documents