Click here to load reader

FACTORS INFLUENCING THE STRENGTH OF FOAMED …eprints.utm.my/id/eprint/40541/5/MohdYazipMatoriMFKA2013.pdf · Adalah didapati kekuatan campuran bitumen buih dari segi modulus, mampatan

  • View
    212

  • Download
    0

Embed Size (px)

Text of FACTORS INFLUENCING THE STRENGTH OF FOAMED...

  • FACTORS INFLUENCING THE STRENGTH OF FOAMED BITUMEN STABILISED MIX

    MOHD YAZIP BIN MATORI

    UNIVERSITI TEKNOLOGI MALAYSIA

  • FACTORS INFLUENCING THE STRENGTH OF FOAMED

    BITUMEN STABILISED MIX

    MOHD YAZIP BIN MATORI

    A thesis submitted in fulfilment of the

    requirements for the award of the degree of

    Master of Engineering (Transportation and Highway)

    Faculty of Civil Engineering Universiti Teknologi Malaysia

    JANUARY 2013

  • iii

    To my beloved Wife, Habibah Bt Ahmad, Son Muhammad Hyqal and Daughter Hyda Yazmin.

  • iv

    ACKNOWLEDGEMENT

    Alhamdullilah, deepest gratitude to Allah S.W.T, for his willing in giving me

    opportunity and strength to complete this study.

    I would like to express my deepest gratitude to my supervisor, Professor Dr

    Mohd. Rosli bin Hainin for his guidance, assistance and moral support throughout

    the period of the study. Suggestion and constructive comments given by him are

    gratefully acknowledged. Special thanks to all staff of Pavement Laboratory,

    Kumpulan Ikram Sdn.Bhd for their assistance and guidance.

    Great thanks and heartfelt acknowledgments are expressed to my family for

    their encouragement, patience and sacrifice from the beginning until the end of my

    study. I am sincerely thankful for their understanding throughout my study,

    especially during the difficult time.

    Last but not least I would like to acknowledge each and every person who has

    contributed to the success of this report, whether directly or indirectly.

  • v

    ABSTRACT

    Recycling of asphalt pavements has increased significantly since 1970 and in

    Malaysia the use of foamed bitumen as stabilizing agent was first introduced in year

    2001. Recycling of asphalt pavements involves mixing of existing pavement material

    with stabilizing agent such as foamed bitumen, bitumen emulsion, cement or lime

    and placed on the milled pavement and compacted. Although the asphalt pavements

    recycling with foamed bitumen as stabilizing agent is gaining recognition and

    acceptance as a cost effective method of rehabilitating distressed pavement, so far in

    Malaysia no study has been carried out on the characteristic of foamed bitumen

    stabilized mix. The strength of foamed bitumen stabilized mix is influenced by

    factors such as cement content, moisture level and curing time. This study evaluates

    the effect of ordinary Portland cement as active filler, curing time and moisture

    content on the strength properties of foamed bitumen stabilized mix. Foamed

    bitumen treated samples with different RAP proportions were tested for their strength

    properties at various active filler contents, curing time and moisture contents. It was

    found that the strength in terms of resilient modulus, Unconfined Compressive

    Strength (UCS) and Indirect Tensile Strength (ITS) values, increased with curing

    time and percentage of active filler. It was also found that the maximum strength in

    terms of resilient modulus, Unconfined Compressive Strength (UCS) and Indirect

    Tensile Strength (ITS) was not at Optimum Moisture Content (OMC) and the

    strength decreased as the RAP proportion increased.

  • vi

    ABSTRAK

    Kitar semula pavemen telah berkembang dengan pesat sejak tahun 1970 dan

    di Malaysia penggunaan bitumen buih sebagai ejen penstabil telah pertama kali

    diperkenalkan pada tahun 2001. Kitar semula pavemen melibatkan proses

    mencampur ejen penstabil seperti bitumen buih, bitumen emulsi, simen atau ‘lime’

    dengan lapisan pavemen sediada, di baur, diturap semula dan kemudiannya

    dipadatkan. Walaupun kitar semula pavemen meggunakan bitumen buih sebagai ejen

    penstabil telah mendapat pengiktirafan dan diterima sebagai kaedah yang kos efektif

    untuk membaiki kerosakan jalan, namun setakat ini tiada kajian yang telah

    dijalankan mengenai ciri ciri campuran ini di Malaysia. Kekuatan atau prestasi

    campuran bitumen buih dipengaruhi oleh beberapa factor seperti kandungan simen,

    kandungan RAP, kandungan lembapan dan masa awet (curing). Kajian yang

    dijalankan ini menilai kesan kandungan RAP, kandungan simen, kandungan

    lembapan dan masa awet (curing) terhadap kekuatan campuran yang distabil dengan

    bitumen buih. Adalah didapati kekuatan campuran bitumen buih dari segi modulus,

    mampatan dan riceh bertambah dengan bertambahnya masa awet (curing) dan

    adanya kandungan simen. Didapati juga kekuatan maksima bagi modulus, mampatan

    dan riceh tidak berlaku pada kandungan lembapan yang optima. Kekuatan campuran

    juga menurun dengan bertambahnya kandungan RAP.

  • vii

    TABLE OF CONTENTS

    CHAPTER TITLE PAGE

    DECLARATION OF THE STATUS OF THESIS

    SUPERVISOR’S DECLARATION

    TITLE PAGE

    DECLARATION ii

    DEDICATION iii

    ACKNOWLEDGEMENT iv

    ABSTRACT v

    ABSTRAK vi

    TABLE OF CONTENTS vii

    LIST OF TABLES x

    LIST OF FIGURES xii

    LIST OF ABBREVIATIONS xiv

    LIST OF APPENDICES xv

    1 INTRODUCTION 1

    1.1 Background 1

    1.2 Problem Statement 2

    1.3 Objectives 3

    1.4 Scope of the study 3

    1.5 Significance of the study 4

    2 LITERATURE REVIEW 5

    2.1 Cold Recycling 5

    2.2 Stabilizing Agent 6

  • viii

    2.3 Foamed Bitumen 7

    2.4 Foamed Bitumen Stabilised Mix 9

    2.5 Property of Aggregate and Reclaimed Asphalt Pavement (RAP) 11

    2.6 Moisture Content and Density Relationship 13

    2.7 Active Filler 15

    2.8 Curing 16

    2.9 Test for Foamed Bitumen Stabilised mix. 18

    2.9.1 Unconfined Compressive Strength Test (UCS) 18

    2.9.2 Indirect Tensile Strength Test (ITS) 19

    2.9.3 Tensile Strength Ratio (TSR)/Moisture Susceptibility 20

    2.9.4 Resilient Modulus Test 21

    3 METHODOLOGY 22

    3.1 Introduction 22

    3.2 Sample Preparation 22

    3.3 Sample Preparation for Foamed Bitumen Stabilised Mix 27

    3.4 Sample Preparation for the effect of curing time 27

    3.5 Sample preparation for the effect of moisture content 28

    3.6 Sample Preparation for the effect of cement content 29

    3.7 Materials 30

    3.7.1 Reclaimed Pavement Samples 30

    3.7.2 Existing Pavement Material 31

    3.8 Laboratory Testing 32

    3.8.1 Aggregate Grading 32

    3.8.2 Determination of MDD/OMC 33

    3.8.3 Determination of the foaming characteristic of the bitumen 34

  • ix

    3.8.4 Preparation of Samples for ITS/UCS and Resilient Modulus 37

    3.8.5 Compaction, curing and testing procedure for ITSdry, ITS soaked and Resilient Modulus 39

    3.8.6 Compaction, curing and testing procedure for UCS 42

    3.8.7 Determination of Design Bitumen Content 45

    3.8.8 Resilient Modulus Test 45

    4 RESULTS AND ANALYSIS 48

    4.1 Introduction 48

    4.2 Effect of Variation of RAP 48

    4.2.1 Grading Analysis 48

    4.2.2 Maximum Dry Density and Moisture Content 50

    4.2.3 Optimum Bitumen Content 51

    4.3 Effect of Variation of Curing Time on Mix 52

    4.3.1 Effect on UCS 52

    4.3.2 Effect on ITSdry 53

    4.3.3 Effect on ITSsoaked 54

    4.3.4 Effect on Resilient Modulus 55

    4.3.5 Effect on Tensile Strength Ratio 56

    4.4 Effect of Variation of Moisture Content on Mix 57

    4.4.1 Effect on UCS 57

    4.4.2 Effect on ITSdry 58

    4.4.3 Effect on ITSsoaked 59

    4.4.4 Effect on Resilient Modulus 60

    4.4.5 Effect on Tensile Strength Ratio 61

    4.5 Effect of Variation of Cement Content on Mix 62

    4.5.1 Effect on UCS 62

  • x

    4.5.2 Effect on ITSdry 63

    4.5.3 Effect on ITSsoaked 64

    4.5.4 Effect on Resilient Modulus 64

    4.5.5 Effect on Tensile Strength Ratio 65

    4.6 Summary of Findings 66

    5 CONCLUSION AND RECOMMENDATION 69

    5.1 Conclusions 69

    5.2 Recommendations 70

    REFERENCES

    APPENDICES

  • xi

    LIST OF TABLES

    TABLE NO. TITLE PAGE

    2.1 Interpretation of ITS tests 20

    3.1 Experimental Matrix of the Study 25

    4.1 Sieve analysis result of RAP/Crusher Run proportion 49

    4.2 Results of MDD and OMC 50

    4.3 Result of Optimum Binder Content 51

  • xii

    LIST OF FIGURES

    FIGURE NO. TITLE PAGE

    2.1 Schematic of the Foamed Bitumen Production 8

    2.2 Dispersion of foamed bitumen particles 10

    2.3 Aggregate grading zones for foamed bitumen 11

    2.4 Cutting drum operation in up-cutting direction 12

    3.1 Works Flow Chart 24

    3.2 RAP and Crushed Aggregate proportion 30

    3.3 Reclaimed Asphalt Pavement (RAP) 31

    3.4 Crushed Aggregate (CR) 31

    3.5 Apparatus for aggregate grading 32

    3.6 Vibrating Hammer method 33

    3.7 Moisture content and dry density relationship 34

    3.8 Half Life/ Expansion ratio 36

    3.9 Foamed bitumen laboratory plant and mechanical mixer 38

    3.10 100mm diameter ITS specimens 40

    3.11 Curing of ITS specimen 40

    3.12 ITS Test 41

    3.13 Soaked specimen 42

    3.14 Mould for UCS test 43

    3.15 150mm diameter UCS specimen 43

    3.16 UCS test 44

  • xiii

    3.17 Measured ITSdry, ITSsoaked, Density and TSR versus Foamed Bitumen Content. 45

    4.1 Results of Grading Analysis 49

    4.2 Dry Density and Moisture Content relationship 50

    4.3 Optimum Binder Content at various RAP contents 51

    4.4 Relationship between UCS and curing time at various RAP contents 52

    4.5 Relationship between ITSdry and curing time at various RAP contents 53

    4.6 Relationship between ITSsoaked and curing time at various RAP contents. 54

    4.7 Relationship between Resilient Modulus and curing time at various RAP contents 55

    4.8 Relationship between Tensile Strength Ratio (TSR) and curing time at various RAP contents. 56

    4.9 Relationship between UCS and moisture content at various RAP contents 57

    4.10 Relationship between ITSdry and moisture content at various RAP contents 58

    4.11 Relationship between ITSsoaked and moisture content at various RAP contents 59

    4.12 Relationship between Resilient Modulus and moisture content at various RAP contents 60

    4.13 Relationship between Resilient Modulus and moisture content at various RAP contents 61

    4.14 Relationship between UCS and cement content at various RAP contents 62

    4.15 Relationship between ITSdry and cement content at various RAP contents 63

    4.16 Relationship between ITSsoaked and cement content at various RAP contents 64

    4.17 Relationship between Resilient Modulus and cement content at various RAP contents 65

    4.18 Relationship between Tensile Strength Ratio (TSR) and cement content 66

  • xiv

    LIST OF ABBREVIATIONS

    ACWC Asphaltic Concrete Wearing Course.

    ACBC Asphaltic Concrete Binder Course.

    RAP Reclaimed Asphalt Pavement.

    C/R Crusher Run.

    OMC Optimum Moisture Content.

    MDD Maximum Dry Density.

    ITS Indirect Tensile Strength test.

    UCS Unconfined Compressive Strength test.

    TSR Tensile Strength Ratio.

    RM Resilient Modulus test.

    CR Cold Recycling.

    CIPR Cold In Place Recycling.

    HMA Hot Mix Asphalt.

    REAM Road Engineering Association Malaysia.

    PF Percentage of Fine

    BC Binder Content.

    OBC Optimum Binder Content.

    MMC Moisture Mixing Compaction.

    BSM Bituminous Stabilised Mix.

  • xv

    LIST OF APPENDICES APPENDIX TITLE PAGE

    A Summary of Test Results – 100% RAP 76

    B Summary of Test Results – 75% RAP + 25% CR 77

    C Summary of Test Results – 50% RAP + 50% CR 78

    D Summary of Test Results – 25% RAP + 75% CR 79

    E Summary of Test Results – 100% CR 80

    F Effect of curing time on UCS and ITSdry 81

    G Effect of curing time on ITSsoaked and Resilient Modulus 82

    H Effect of curing time on Tensile Strength Ratio (TSR) 83

    I Effect of cement content on UCS and ITSdry 84

    J Effect of cement content on ITSsoaked and Resilient Modulus 85

    K Effect of cement content on Tensile Strength Ratio (TSR) 86

  • 1

    CHAPTER 1

    INTRODUCTION

    1.1 Background

    Recycling of asphalt pavements has increased significantly since 1970. In

    Malaysia the cold recycling technique which involved in-plant recycling or in-situ

    recycling with foamed bitumen was first introduced in 2001. Since then the

    technique has become popular as a viable alternative pavement rehabilitation

    measure. The technique involves milling of existing pavement, mixed with the

    stabilizing agent and placed on the milled pavement and compacted. The most

    common stabilizing agents used for cold recycling in Malaysia are foamed bitumen,

    bitumen emulsion, cement and lime. The cold recycling process is carried out either

    in plant or in situ using purposed built recycling machine and recycled layer will

    form a new road base stabilized layer. It is a normal practice in Malaysia to overlay

    the newly stabilized roadbase layer with 60mm thick of binder course and 50mm

    thick of wearing course layers.

    Although the cold recycling technique with foamed bitumen is gaining

    recognition as a cost effective method of rehabilitating distressed pavement, so far in

    Malaysia no study has been carried out on the characteristic of foamed bitumen

    stabilized mix. The performance of the recycled asphalt layer depends on the

    proportion of reclaimed asphalt pavement (RAP), types of stabilizing agents, and

    amount of cement [1]. Therefore, the purpose of this study is to evaluate in the

  • 2

    laboratory the effects of RAP, moisture content, curing time and cement to the

    strength properties of foamed bitumen stabilized mix.

    1.2 Problem Statement

    A number of cold recycling projects with foamed bitumen stabilised mix

    have been completed in Malaysia for the past 10 years and on-going performance

    monitoring are in progress. However, despite such progress, option on foamed

    bitumen has been limited because of the lack of a standardized mix design,

    construction procedure and gaps that exist between the current knowledge and the

    knowledge that is needed to increase the probability of success when using this

    technology, particularly in the Malaysian hot and wet environment.

    Important factors for the success of cold recycling works include site

    investigation, evaluation of existing materials, laboratory mix design and

    construction by appropriately skilled contractors. Before the cold recycling project

    start, representative samples from the existing pavement are obtained and samples

    are prepared to simulate as close as possible the property of material to be achieved

    during the actual recycling process, but it must be also noted that the mix design

    process or procedure cannot fully simulate what will happen in the field at the time

    of construction. Because of inconsistency of pavement layer thickness and moisture

    content from the existing pavement, field adjustments are sometime necessary, such

    as increasing water or stabilizing agent content.

    This experimental laboratory works simulate the on- site condition of the

    foamed bitumen stabilised mix and the study is therefore aimed to answer problems

    with regard to the effect of RAP, cement content, curing time and moisture content to

    the strength properties of foamed bitumen stabilised mix. Among the problems faced

    during the construction of a cold recycling project are;

    i. Proportion of RAP and the existing unbound material is not consistent, as

    the pavement layer thicknesses vary from place to place.

  • 3

    ii. During construction, it is difficult to meet the optimum moisture content

    (OMC) and maximum dry density (MDD) target, existing moisture

    content at the site normally varies from place to place.

    iii. Before the recycling commences, cement in powder form is spread

    manually based on pre-determined percentage required. During

    construction the quantity or percentage of cement will vary because of

    the cement being blown away by the movement of heavy traffic and by

    strong wind.

    iv. After the completion of recycling works, the determination of the

    appropriate curing time before foamed bitumen stabilised layer can be

    opened to traffic or be paved with asphaltic layer ACBC and ACWC

    depends on the judgment of the contractor based on previous experience.

    1.3 Objectives

    The objectives of this study are:

    i. To investigate the effect of cement, moisture content and curing time at

    varying RAP proportions to the strength of foamed bitumen stabilised

    mix.

    ii. To analyse and compare the results obtained with the requirement of the

    National Specification for Roadworks.

    iii. To provide recommendations on the required cement content, moisture

    content and curing time for foamed bitumen stabilised mix based on the

    findings of the research.

    1.4 Scope of the Study

    The scope of the study covers the strength test for the foamed bitumen stabilised

    mix and the study is limited to the evaluation of the specimens prepared in the

    laboratory. The scope of this study is as follows:

  • 4

    i. To review and research the literature relating factors influencing the

    strength of foamed bitumen stabilised mix.

    ii. Development of work flow chart and experimental test matrix for the

    study.

    iii. Preparation of test specimens in accordance with prescribed procedures.

    For the purpose of this study the materials used are limited to;

    RAP from Grand Saga mill and replace project.

    Aggregate (CR) from Kajang Rock Quarry.

    Bitumen Penetration Grade 80/100 from SHELL.

    iv. Investigation and laboratory testing on the strength of the foamed bitumen

    stabilised mix and the laboratory tests carried out are as follows:

    Unconfined Compressive Strength test (UCS).

    Indirect Tensile Strength test (ITS) at dry and soaked condition.

    Determination of Tensile Strength Ratio (TSR).

    Resilient Modulus Test (RM).

    v. Analysis of the test results and evaluating the strength properties of the

    foamed bitumen stabilised mix.

    vi. Findings, conclusion and recommendation from this study for further

    research.

    1.5 Significance of the Study

    Although the cold recycling technique with foamed bitumen is gaining

    recognition and acceptance as a cost effective method of rehabilitating distressed

    pavement, so far in Malaysia no study has been carried out to study the characteristic

    of foamed bitumen stabilized mix. Very little local data is available and the results

    and output of this study can be used for the development of standard specification

    and guidelines for cold recycling with foamed bitumen in Malaysia.

  • 72

    REFERENCES

    1. Cooley A. Dane. Effects of Reclaimed Asphalt Pavement on Mechanical

    Properties of Base Materials. A thesis submitted to the faculty of Brigham

    Young University. 2005

    2. Prithvi S. Kandhal. Recycling of Asphalt Pavements – An Overview of

    Current Practices. 2nd International Symposium on Maintenance of Pavement

    and Technological Control. July 29 – August 1, USA. 2001.

    3. Myre Jostein. The Use of Cold Bitumen Stabilized Base Course Mixes in

    Norway. Norweigian Public Road Administration. 2001.

    4. U.S Department of Transportation. Federal Highway Administration.

    Recycling Guidelines for State and Local Governments. Publication No.

    FHWA-SA-98-042. December 1997.

    5. Sufian et al. Cold In Place Recycling in Malaysia. International Symposium

    on Pavement Recycling. Sao Paolo, Brazil. 2005.

    6. Lewis AJN et al. Cold in Place Recycling: A relevant Process for Road

    Rehabilitation and Upgrading. 7th Conference on Asphalt Pavements for

    Southern Africa. CAPSA. 1999.

    7. K M Muthen. Foamed Asphalt Mixes – Mix Design Procedure. Contract

    Report CR – 98/077. December 1998.

    8. S. A. Romanoschi et al. Asphalt Stabilized Reclaimed Asphalt Pavement: A

    Promising Technology for Mid-Western Roads. Proceedings of the 2003

    Mid-Continent Transportation Research Symposium. Ames, Iowa. August

    2003.

  • 73

    9. KJ Jenkins et al. Characterization of Foamed Bitumen. 7th Conference on

    Asphalt Pavements for Southern Africa (CAPSA). 1999.

    10. Asphalt Academy SA. Technical Guideline: Bitumen Stabilised Materials –

    A Guideline for the Design and Construction Bitumen Emulsion and Foamed

    Bitumen Stabilised Materials, TG 2, Second Edition. May 2009.

    11. Marcelo C Curi. Cold Recycling with Foam Bitumen. 2nd International

    Symposium on Maintenance of Pavement and Technological Control, USA.

    July 29 – August 1, 2001.

    12. FSV. De Souza et al. Foamed Bitumen Experiences in Pavement

    Rehabilitation in Brasil: Potential for Use on High Volume Roads. 2nd

    International Symposium on Maintenance of Pavement and Technological

    Control. USA. July 29 – August 1, 2001.

    13. Akeroyd F.M.L. & Hicks B.J. Foamed Bitumen Road Recycling. Highways.

    Volume 56, Number 1933. 1988. 42 - 45.

    14. Ruckel P.J., Acott S.M. & Bowering. Foamed-asphalt paving mixtures:

    preparation of design mixes and treatment of test specimens in asphalt

    materials, mixtures, construction, moisture effects and sulfur. Washington,

    DC: Transportation Research Board (Transportation Research Record; 911).

    1982. 88-95.

    15. Road Engineering Association Malaysia (REAM). Specification For Cold

    In-Place Recycling. 2005.

    16. Sakr H.A. & Manke P.G. Innovations in Oklahoma foamix design

    procedures in asphalt materials, mixes, construction and quality. Washington

    DC Transportation Research Board. (Transportation Research Record;1034).

    1985. 26-34.

  • 74

    17. Bissada A.F. Structural response of foamed-asphalt-sand mixtures in hot

    environments in asphalt materials and mixtures. Washington, DC:

    Transportation Research Board. (Transportation Research Record, 1115).

    1987. 134-149.

    18. Semmelink C.J. The effect of material properties on the compactibility of

    some untreated road building materials. PHD thesis, University of Pretoria,

    Pretoria. 1991.

    19. Bowering R.H. Properties and Behavior of Foamed Bitumen Mixtures for

    Road Building. Proceedings of the 5th Australian Road Research Board

    Conference. Canberra, Australia. 1970.

    20. Lee D.Y. Treating marginal aggregates and soil with foamed asphalt. In

    Proceedings of the Association of Asphalt Paving Technologists (Vol 50).

    1981. 211-150.

    21. Castedo-Franco L.H. & Wood E.L. Stabilisation with foamed asphalt of

    aggregates commonly used in low volume roads. 3rd International

    Conference. Washington DC Transportation Research Board. (Transportation

    Research Record; 898). 1983. 297-302.

    22. Wirtgern GmbH. Wirtgern Cold Recycling Manual. 2nd Edition, ISBN 3-

    936215-05-7. Windhagen, Germany. 2004.

    23. Lee D.Y. Treating Iowa’s Marginal Aggregates and Soils by Foamix

    Process. Iowa State University. May 1980.

    24. Sri Sunarjono. Tensile Strength and Stiffness Modulus of Foamed Asphalt

    Applied to A Grading Representative of Indonesian Road Recycled Pavement

    Materials. Dinamika Teknik Sipil, Volume 7. January 2007. 1 – 10.

    25. Maccarrone, S., Holleran, G. & Ky. A Cold Asphalt System as an Alternative to Hot

    Mix. In 9th AAPA International Asphalt Conference. 1995.

  • 75

    26. Van Wijk A. and L.E. Wood. Use of Foamed Asphalt in Recycling of an

    Asphalt Pavement. In Transportation Research Record No. 911,

    Transportation Research Board. Washington DC. 1983. 96-103.

    27. Bowering R.H. & Martin C.L. Performance of newly constructed full depth

    foamed bitumen pavements. In Proceedings of the 8th Australian Road

    Research Board Conference. Perth, Australia. 1976.

    28. Ramanujam J.M. and D.P. Fernando. Foam Bitumen Trial at Gladfield-

    Cunningham Highway. In the Proceedings of the Southern Region

    Symposium. Australia. 1997.

    29. Lancaster. J., L. McArthur, and R. Warwick. VICROADS experience with

    foamed bitumen stabilization. In the Proceedings of the 17th ARRB

    Conference. Volume 17, Part 3. Gold Coast, Queensland. August 15-19,

    1994. 193-211.

    30. M Houston and F.Long. Correlations Between Different ITS and UCS Test

    Protocols for Foamed Bitumen Treated Materials. Proceedings of the 8th

    Conference on Asphalt Pavements for Southern Africa (CAPSA). 2004.