FORENSIC ENGINEERING TESTING TECHNIQUES FOR STRUCTURAL ASSESMENT: A CASE STUDY ON PRE-STRESSED

REINFORCED CONCRETE BRIDGE AT KLANG VALLEY

GOPINATH MUNIANDY

A project report submitted in partial fulfillment of requirement for the award of the degree of

Master of Science (Construction Management)

Faculty of Civil Engineering

UnNersiti Teknologi Malaysia

APRIL 2010

ABSTRACT

Integrity test on existing concrete structures is often being carried out to

determine the assessment for the structure through several aspects such as to determine

the whether the structure is suitable for its designed use, for proposed change of usage or

extension of a structure, to enswe the acceptability of structure following to any

deterioration or structural damage. The evaluation of integrity of existing concrete

structures has been carried out through several testing methods and procedures such as

non destructive test (NDT) and partially destructive test using sophisticated testing

techniques. However, the criteria of selection for suitable testing method and techniques

is still are being unclear depending types of structure that need to be tested. The criteria

determination of most suitable codes and standards specification for Malaysia

perspective is also unclear. Therefore, it is vital to study the reality in selecting most

suitable testing method incorporated with most suitable codes and standardizations to

carry out integrity test on existing concrete structures in Malaysia.

This case study consisting testing on existing concrete structures using concrete

core method, rebound hammer test and ultra sonic pulse velocity OJPV) on existing pre-

stressed T-beam and concrete structures of an unnamed bridge in Klang Valley. Results

obtained from testing tabulated for comparison between BS 1881& BS 6089 cube

characteristic strength and BSEN 13791, 2007 cube characteristic strength. Selected

civil and structural consulting engineers was interviewed using prepared questionnaire to

identify the selection criteria and views in selecting appropriate testing method to

evaluate integrity of existing concrete structures. Finally, the factors influencing

selecting the most suitable testing method and comparison of selected standard code and

practice identified.

Konkrit merupakan di antara bahan bina yang sering digunakan di dalam projek

kejuruteraan awam di Malaysia. Di antara alasan penggunaanya adalah faktor ekonomi

dan keperluan pembaik pulihan yang rendah sepanjang tempoh keboleh khidrnatannya.

Walau bagaimanapun, konkrit mengalami beberapa kerosakan dan kemerosotan

sepanjang hayatnya kerana kekurangan pengetahuan pada sifat dan kelakuannya.

Dengan mengunakan teknik-tehik untuk pemeriksaan kualiti konkrit bagi struktur yang

sedia ada ama ada ujian separa musnah ataupun tak musnah, kualiti konkrit yang hendak

diuji boleh dikenalpasti. Namun, dalam persepti Negara kita, criteria untuk

mengenalpasti ujian konkrit bagi tujuan kajian tertentu masih tidak ada definasi dengan

mengambil kira kod-kod specifikasi yang tertentu. Maka, adalah pentingnya untuk

membuat kajian untuk mengenalpasti criteria untuk pilihan ujian konkrit mengikut kod-

kod specifikasi tertentu untuk mengenalpasti ujian yang terbaik untuk pemeriksaan

kualiti struktur konkrit yang sedia ada.

Kajian ini termasuk membuan ujian konkrit yang dipilih iaitu "Schmidt rebound

hammer", "Ultrasonicpulse velocity'' dan "core test". Kajian in telah dilalukan atas

jambatan yang sedia ada di Pelabuhan Klang. Segala keputusan akan ditafsirkan

mengunakan bentuk jadual dan graf untuk analysis. Data kajian juga telah dibezakan

mengunakan kod-kod specifikasi yang dipilih untuk mendapatkan perbezaan dalam

penerimaan data untuk tujuan analisis. Kajian juga dilalukan dalam bentuk temurah

dengan pakar jurutera yang berpengalaman dalam bidang kajian konkrit mengunakan

boring sod selidik. Segala keputusan temuramah di pamerkan dalam bentuk jadaul dan

graf. MelaIui kajian ini, mendapat tahu bahawa, ujian "concrete core" memberikan data

keputusan yang lebik relevan berbanding dengan keputusan ujian yang lain. Ujian

"conaete core" juga disetujui oleh pakar-pakar jurutera yang terlibat dalam bidang

kajian konkrit.

rr

rr

Z

fi

Pw

tQ

r

2.2.2.4 Determination of Pulse Velocity 21

2.2.2.4.1 Transducer Arrangement 21

2.2.2.4.2 Determination of Pulse Velocity by Direct

Transmission 23

2.2.2.4.3 Determination of Pulse Velocity by

Semi-Direct Transmission 23

2.2.2.4.4 Determination of Pulse Velocity by Indirect

or Surface Transmission 24

2.2.2.4.5 Coupling the Transducer onto the Concrete 25

2.2.2.4.6 Factor Influencing Pulse Velocity

Measurements 27

2.2.2.5 Determination of Concrete Uniformity 31

2.2.2.6 Detection of Defects 32

2.2.2.7 Examples of Relationships between Pulse

Velocity and Compressive Strength 33

2.3 Partially Destructive Test

2.3.1 Concrete Core Test

2.3.2 Cores vs. Cylinders

2.3.3 Coring Direction

2.3.4 Top-to-Bottom Strength Variation

2.3.5 Consolidation

2.3.6 Effects of Curing

CHAPTER III

2.4 Codes, Standards and Specifications 41

2.4.1 General Considerations 42

2.4.2 Different Categories of Standards 43

2.4.2.1 Standards 43

2.4.2.2 Codes and Specifications 43

2.4.2.3 Other Types of National Documents 44

2.4.2.4 Standardisation Organisations and Some of

the Standards Relating to Testing of Concrete 44

2.4.2.4.1 American Society for Testing and Materials

(ASTM) 44

2.4.2.4.2 British Standards Institution (BSI) 46

METHODOLOGY

3.1 Introduction 48

3.2 Document Study 49

3.2.1 Concrete Core Test 49

3.2.2 Schmidt Rebound Hammer Test 51

3.2.3 Ultrasonic Pulse Velocity Test 52

3.3 Interview with Civil and Structural Consulting Engineers

Using Questionnaire 53

3.3.1 Contents of the Questionnaire 53

3.4 Comparison of Cube characteristic Strength using

BS 1881& BS 6089 and BSEN 13791:2007 Euro Codes 56

LIST OF TABLES

TABLE NO TITLE

Effect of temperature on pulse transmission

Effect of specimen dimensions on pulse transmission

Classification of the quality of concrete on the basis of

pulse velocity 30

Rebound Hammer Test Results

Measurement for Rebound Hammer UPV Test locations on

the T-Beam

Ultrasonic Puke Velocity Test Results

Concrete Core Compression Test Results

Estimated In-Situ Strength throughout Interpolation fiom

Correlation Curve

Estimated In-Situ Cube Strength for all three types of test

Comparison of Cube characteristic Strength using BS 1881&

BS 6089 and BSEN 13791:2007 E m Codes

Variance between there types of test conducted

Variance between BS 1881 and BSEN 13791

PAGE

LIST OF FIGURES

FIGURE NO TITLE

1.1 Research Methodology Flow Chart

2.0 Schmidt Rebound Hammer

2.1 A cutaway schematic view of the Schmidt rebound hammer

2.2 Relationship between 28 day compressive strength and

rebound number for limestone aggregate concrete obtained

with Type N-2 Hammer

2.3 Correlation curves produced by different researchers.

(Greene curve used Type N hammer; others used Type N-2).

2.4 Effect of gravel from different sources on correlation curves.

2.5 Comparison between correlation curves for crushed

limestone and siliceous

2.6(a) Direct Transmission

2.6(b) Semi-direct Transmission

2.6(c) Indiuect or surface transmission

2.7 Pulse velocity determinations by indirect (surface) transmission

2.8 Relation between ultrasonic pulse velocity and compressive

strength for concretes of different mix proportions

2.9 Planes of weakness under coarse aggregate particles due to

bleeding

2.10 Estimated within-member strength variations

2.11 Longitudinal resonance frequency of concrete cores

3.1 Photographs showing the process of concrete core sample testing

PAGE

Photographs showing the process of Schmidt rebound

hammer testing 5 1

Photographs showing the process of UPV testing 52

Top View of T-Beam L=PBiPC-S2-EX-01 59

Side View of T-Beam L=PB/PC-S2-EX-01 59

Correlation Curve of UPV against Estimated In-situ Cube Strength 62

Factors Influencing in Selecting Method of Testing 64

Proportions of nature of test by respondents 65

Responses on Partially Destructive Test Preference 65

Responses on Partially Destructive Test Preference 66

Responses on selection of standard codes and practice for

structural assessment 67

CHAPTER I

INTRODUCTION

1.1 Introduction

Integrity test on existing concrete structures is often being carried out to

determine the assessment for the structure through several aspects such as to determine

the whether the structure is suitable for its designed use, for proposed change of usage or

extension of a structure, to ensure the acceptability of structure following to any

deterioration or structural damage such as caused by fue, blast, fatigue or overload and

to ensure the serviceability or adequacy of member known or suspected to contain

material which does not meet specifications or with design faults.

The fundamental of structural integrity and durability is to develop continuous

monitoring concepts for structural concepts for structural components and for the global

behavior. A structure is said to have general structural integrity if localized damage does

not lead to widespread collapse. Structural integrity has to be guaranteed by the

structural safety under ultimate and serviceability conditions and by ductility as well as

redundancy of load path.

The integrity of concrete structures can justify by using several tests available for

testing concrete range from completely non-destructive, where there is no damage to the

concrete, through those where the concrete surface is slightly damaged, to partially

destructive test, such as core test, and pullout and pull off test, where the surface has to

be repaired after the test. The range of properties that can be assessed using non-

destructive test and partially destructive test quite large and includes such fundamental

parameters as density, elastic modules, and strength as well as surface hardness and

surface absorbtionand reinforcement location, size and distance fiom the surface. At

times, it is also possible to check the quality of workmanship and structural integrity by

the ability of detects void, cracking and delamination.

The assessment of integrity of existing concrete structures should also taken into

consideration of requirements of several codes, standards, specification and procedures

established by most countries national bodies and relevant organizations. Standards can

play important role in international co-operation when they are used in contracts. The

growth in international trade has resulted in a growth in the need for International

Standards which can be acceptable compromise between different national standards.

1.2 Problem Statement

Integrity test on existing concrete structures is being implemented widely in

Malaysian concrete structures that deteriorate as the effects of structural and

environments loading take place over time. The evaluation of integrity of existing

concrete structures has been canied out through several testing methods and procedures

such as Non Destructive Test W T ) and partially destructive test using sophisticated

testing techniques. However, the criteria of selection for suitable testing method and

techniques is still are being unclear depending types of structure that need to be tested.

The criteria determination of most suitable codes and standards specification for

Malaysia perspective is also unclear. Therefore, it is vital to study the reality in selecting

most suitable testing method incorporated with most suitable codes and standardisation

to carry out integrity test on existing concrete structures in Malaysia.

1.3 Research Objectives

The main objectives of this study are as per listed below:-

i. To identify the factors that influences in selecting the most suitable testing method

and procedures to conduct integrity test on existing concrete structures.

ii. To analyse and compare on selected codes of practice and standardization for

integrity test on existing concrete structures

1.4 Research Scope

This case study scope will be focusing on testing methods and techniques on

existing concrete structures incorporated with comparison of codes of practice and

standardisation established by BS 1881, BS 6089 and BSEN 13791. This case study is

based on several concrete core results obtained from testing carried on existing bridge

concrete structures and pre-stressed concrete beams located in Klang Valley. The details

of the project will not be illustrated because the project contains certain confidential

statements.

1.5 Research Methodology

This case study will be consisting testing on existing concrete structures using

concrete core method, rebound hammer test and Ultra sonic Pulse Velocity (WV) on

existing concrete structures of an unnamed bridge in Klang Valley. Results will be

tabulated for comparison between BS 1881, BS 6089 and BSEN 13791. Results will be

analyzed using calculation for cube characteristic strength and design requirement and

acceptability of the results obtain from the tabulation and wrapped out with conclusion

and recommendations. Recommendations will be an overview on options for

strengthening the affected structures. The methodology flow chart are shown as below as

in Figure 1.1.

I DEFINE THE PROBLEM I

SPECIFY THE OBJECTIVES

4 LITERATURE REVIEW

I COLLECTING DATA I

DATA STUDY -Data obtained form Rebound Hammer Test, Ultrasonic Pulse Velocity and Concrete Core Sample will be analyzed and presented.

INTERVIEW -Interview five experiences C&S consulting engineers using prepared questionnaire.

COMPARISON - BS 81 10&BS 6089 cube characteristic strength and BSEN 137912007 cube characteristic strength.

I ANALYSIS AND RESULTS I

CONCLUSION AND RECOMMEND A TION

Figure 1.1: Research Methodology Flow Chart

REFERENCES

British Standard Institution, Non-destructive methods of test for concrete-

Electromagnetic cover measuring devices, British Standard 4408, London, 1.

BS EN 12504:1:2000 Part 1. Testing concrete in structures. European Committee for

Standardisation.

BS 1881: Part 5 Methods of determine concrete core strength. British Standards

Institution, London.

BS 1881-120: (1983). Testing concrete in structures. British Standards Institution,

London.

Bungey, J.H and Millard, V.S. (1982). The testing of concrete for structural assessment.

Christ, A.K. (1992). Standard test for repair materials and coating*& 1.CIRIA.

Facaoaru, I. (1984). Romania achievements in non-destmctive strength of concrete.

American Concrete Institute, special publishes Vol. SP 93-16.

Fleischer, C.C. and Chapman-Andrew. (1993). Guide for evaluation of concrete

structures. American Concrete Institute Material Journals, special publish Vol. SP 93-

45.

Gallan, A. (1976). Estimate of concrete strength by ultrasonic pulse velocity and

damping constant. American Concrete Institute Journal, special publish Vol 76-34.

Leshchinsky, A.M. (1990). Variability of non-destructive methods for determination of

strength of concrete. Magazine of Concrete Research, British Structural Engineers

Counsel. Vol65b

Malhotra, V.M (1984). The iduence of reinforcement on ultrasonic pulse velocity

testing. American Convrete Institute, special publish Vol84-78.

Morey, T.F and Kovacs-John, L.L. (1977). Determination of concrete wre strength for

structural assessment. American Concrete Iistitute Journal, special publish Vol77-21.

Peterson, C.G and Poulsen, E. (1996). In-situ partially destructive methods to determine

concrete strength.

Reynolds, W.N. (1984). Measuring concrete quality non-destructively. British Journal of

NDT. Vol665

Russell Fling, S. (1977). Pull-out test. Handbook on Non-Destructive Testing of

Concrete. CRC Press, Boston, USA.

T a m e , L.K and Lambotte, S.S. (1991). Determination of concrete strength for existing

structure.