A study on adhesion between emulsion and mineral aggregates from various sources applying in chip seal in takeo province, cambodia

kBleeding kor kflushing ksurfaces kthat kare kconsidered kfor kchip kseal kapplications kshould kbe ktreated kcarefully kbecause kflushing kis kgenerally kaffected kon kthe knew kchip ks

VIETNAM hNATIONAL hUNIVERSITY hHOCHIMINH hCITY

HOCHIMINH hCITY hUNIVERSITY hOF hTECHNOLOGY

-

DUK HENG

A STUDY ON ADHESION BETWEEN EMULSION AND MINERAL AGGREGATES FROM VARIOUS SOURCES APPLYING IN CHIP SEAL IN TAKEO PROVINCE, CAMBODIA

MAJOR: TRANSPORTATION ENGINEERING

MAJOR CODE: 60580205

MASTER DEGREE THESIS

HOCHIMINH CITY–Feb 2020

CÔNG hTRÌNH hĐƯỢC hHOÀN hTHÀNH hTẠI TRƯỜNG hĐẠI hHỌC hBÁCH hKHOA h–ĐHQG h-HCM

Cán hbộ hhướng hdẫn hkhoa hhọc h: hPGS.TS. hNguyễn hMạnh hTuấn

h

Cán hbộ hchấm hnhận hxét h1 h: h PGS.TS. hLê hAnh hThắng

hCán hbộ hchấm hnhận hxét h2 h: hTS. hLê hVăn hPhúc

hLuận hvăn hthạc hsĩ hđược hbảo hvệ htại hTrường hĐại hhọc hBách hKhoa, hĐHQG hTp

hHCM hngày h11 htháng h01 hnăm h2020

Thành hphần hHội hđồng hđánh hgiá hluận hvăn hthạc hsĩ hgồm:

1. hChủ htịch hhội hđồng: hTS. hLê hBá hKhánh

2 hThư hký: hTS hHuỳnh hNgọc hThi

3. hPhản hbiện h1: h PGS.TS. hLê hAnh hThắng

4. hPhản hbiện h2: hTS. hLê hVăn hPhúc

5. hỦy hviên: hPGS.TS. hNguyễn hMạnh hTuấn

Xác hnhận hcủa hChủ htịch hHội hđồng hđánh hgiá hLV hvà hTrưởng hKhoa hquản hlý

hchuyên hngành hsau hkhi hluận hvăn hđã hđược hsửa hchữa h(nếu hcó)

TS. hLê hBá hKhánh PGS.TS Lê Anh Tuấn

ĐẠI HỌC QUỐC GIA TP HCM

TRƯỜNG ĐẠI HỌC BÁCH KHOA

323

CỘNG HÒA XÃ HỘI CHỦ NGHĨA VIỆT NAM

Độc lập – Tự do – Hạnh phúc

323

NHIỆM hVỤ hLUẬN hVĂN hTHẠC hSĨ

Họ htên hhọc hviên: DUK HENG MSHV: 1779003

Ngày, tháng, năm sinh: 10/08/1991 Nơi sinh: Campuchia

Chuyên hngành: hKỹ hthuật hxây hdựng hcông htrình hgiao hthông h Mã hsố: 60580205

I TÊN ĐỀ TÀI: “Nghiên cứu khả năng dính bám giữa nhũ tương nhựa với đá từ

một số nguồn sử dụng trong áo đường láng nhựa ở Tỉnh Takeo, Campuchia”,

“A Study on Adhesion between Emulsion and Mineral Aggregates from Various Sources Applying in Chip Seal in Takeo Province, Cambodia”

II NHIỆM VỤ VÀ NỘI DUNG:

 Thí nghiệm xác định tính chất của đá từ các nguồn khác nhau

 Xác định mất mát đá theo thí nghiệm quét bề mặt Sweep ASTM D7000

 Xác định độ dính bám theo thí nghiệm va đập Vialit BS EN 12272-3

 Xác định độ dính bám theo thí nghiệm của TCVN 8817-15:2011

 Sử dụng phương pháp phân tích hình ảnh vào thí nghiệm TCVN 8817-15:2011

 So sánh độ dính bám của đá với nhũ tương từ các thí nghiệm khác nhau trên

 Xác hđịnh hmối hquan hhệ htương hquan hgiữa hcác htham hsố htrong hthí hnghiệm htrên

III NGÀY hGIAO h NHIỆM h VỤ: 19/08/2019

IV NGÀY h HOÀN h THÀNH h NHIỆM h VỤ: 08/12/2019

V CÁN h BỘ h HƯỚNG h DẪN: PGS.TS Nguyễn Mạnh Tuấn

Tp HCM, ngày 19 tháng 08 năm 2019

PGS.TS Nguyễn Mạnh Tuấn PGS.TS Nguyễn Mạnh Tuấn

TRƯỞNG KHOA KỸ THUẬT XÂY DỰNG

PGS.TS Lê Anh Tuấn

ACKNOWLEDGEMENT

I kwould kfirst klike kto kthank kmy kadvisor kMr. kNguyen kManh kTuan k(PH.D,

kAssoc. kProf), kHead kof kDepartment kof kBridge kand kHighway kEngineering kat

kHochiminh kCity kUniversity kof kTechnology, kVietnam. kThe kdoor kto khis koffice kand

khis ktime kwere kalways kopened kwhenever kI kran kinto ktrouble kspot kor kwhenever kI

khad kquestions kabout kmy kresearch kand kthesis. kHe khelps kme kand ksteered kme kin kthe

kright kdirection kwhenever khe kthought kI kneeded kit

I kwould kalso klike kto kthank kto kthe kLaboratory kin kDepartment kof kBridge kand

kHighway kEngineering kat kHochiminh kCity kUniversity kof kTechnology-Vietnam kand

kthe kLaboratory kof kConstruction kand kPublic kWorks-Cambodia kthat kallowed kme kto

kaccomplish kmy klaboratory ktests. kWithout ktheir kpassionate kparticipation kand khelps,

kmy klaboratory ktests kcould knot khave kbeen ksuccessfully kconducted

Finally, kI kmust kexpress kmy kvery kprofound kgratitude kto kmy kparents, kto kmy

kbrother kand ksister, kmy krelatives, kmy klecturers kat kDepartment kof kBridge kand

kHighway kEngineering, kand kmy kco-workers kat kPublic kWorks kand kTransportkDepartment k(Ministry kof kPublic kWorks kand kTransport) kfor kproviding kme kwith

kunfailing ksupport kand kcontinuous kencouragement kthroughout kmy kyears kof

kstudying kand kthrough kthe kprocess kof kmy kresearching kand kwriting kthis kthesis. kThis

kaccomplishment kwould knot khave kbeen kpossible kwithout kthem

Thank kyou!

DUK HENG

TÓM TẮT LUẬN VĂN

Áo hđường hláng hnhựa hlà hloại hmặt hđường hđược hsử hdụng hrất hphổ hbiến htrên hthế

hgiới hhiện hnay hnói hchung hvà hở hCampuchia hnói hriêng hbiệt hvì hloại hmặt hđường hláng

hnhựa hcó hnhiều hhiệu hquả hvề hmặt hchi hphí hvà hthi hcông. hĐể háp hdụng hloại hmặt hđường

hnày hmột hcách hhiệu hquả htrên hcác htuyến hđường, hta hnhất hthiết hcần hkiểm hsoát hvà hhạn

hchế hđược hcác hhư hhỏng hthường hxảy hra htrong hmặt hđường hláng hnhựa. hHai hhình hthức

hhư hhỏng hcủa hmặt hđường hláng hnhựa hmà hđáng hquan htâm hnhất hlà hhiện htượng htổn hthất

hđá hvà hhiện htượng hchảy hnhựa. hHai hhiện htượng hhư hhỏng hnày hđều hxảy hra hdo hkhả hnăng

hdính hbám hgiữa hcốt hliệu hđá hvới hchất hkết hdính hkhông htốt. hBởi hvậy hcó hrất hnhiều htác

hgiả htrên hthế hgiới hđã hvà hđang hnghiên hcứu hvề hliên hkết hdính hbám hgiữa hcốt hliệu hđá hvới

hchất hkết hdính htrong háo hđường hláng hnhựa, hvà hhọ hcũng hnghiên hcứu hvề hcác hyếu htố

hảnh hhưởng hđến hcơ hchế hlàm hviệc hcủa hliên hkết hđó. hKết hquả hnghiên hcứu hcủa hcác hnhà

hnghiên hcứu hvà hcác htác hgiả hcho hthấy hnhiều hyếu htố hảnh hhưởng hđến hkhả hnăng hdính

hbám hgiữa hcốt hliệu hđá hvà hchất hkết hdính hnhư hloại hchất hkết hdính h(nhựa hthường, hnhũ

htương hnhựa, hnhựa, hhắc hín…), hcác htính hchất hcơ hlý hcủa hcốt hliệu, hnhiệt hđộ, hyếu htố hthi

hcông hchẳng hhạn

Trong hnghiên hcứu hnày, hđược hthực hhiện hđể hđánh hgiá hkhả hnăng hdính hbám

hgiữa hcốt hliệu hđá hvới hnhũ htương hnhựa. hCốt hliệu hđá hđược hthu hthập htừ h5 hmỏ hđá hở

hCampuchia hđang hsử hdụng htrong háo hđường hláng hnhựa hở htỉnh hTakeo. hViệc hđánh hgiá

hkhả hnăng hdính hbám hgiữa hcốt hliệu hđá hvới hnhũ htương hnày hnhằm htìm hhiểu hvề hcác hyếu

htố hvà hcác hđiều hkiện hđang hảnh hhưởng htới hchất hlượng háo hđường hláng hnhựa hở

hCampuchia hhiện hnay. hHơn hnữa, hnghiên hcứu hnày hcũng htìm hhiểu hvà hđưa hra hcác hthí

hnghiệm hđánh hgiá hkhả hnăng hdính hbám hgiữa hcốt hliệu hđá hvới hchất hkết hdính hnhũ htương

hcho hphù hhợp htrong hviệc hkiểm hsoát hchất hlượng háo hđường hláng hnhựa htrong htương hlai,

hvà hnghiên hcứu hnày hcũng hlà hmột hphần htham hgia hviệc hcập hnhật hquy hchuẩn hvề háo

hđường hláng hnhựa hở hCampuchia hcho hhiệu hquả hhơn

SUMMARY

Chip hseal his ha hkind hof hpavement hsurface htreatment hthat his hpopular huse

haround hthe hworld hand hespecially hin hmy hcountry-Cambodia hbecause hof hits hcost

heffectiveness hand hconstruction hconvenience. hTo hget ha hhigh hquality hchip hseal, htwo

hmost hpopular htypes hof hdeterioration hin hchip hseal hperformance hshould hbe hcontrolled

hand hlimit hto hthe hminimum. hThose hdeteriorations hare hraveling h(loss hof haggregate)

hand hbleeding hthat hthey hrelate hto hthe hadhesivity hcharacteristics hbetween haggregate

hand hasphalt hbinders. hMany hstudies hhave hfocused hon hadhesion hbond, hand hfactors

heffect hon hadhesion hperformance hbetween haggregate hand hbinder. hThey hhave hfound

hmany hfactors hhave haffected hon hadhesion hbond hbetween haggregate hand hbinder hsuch

has htypes hof hbinder h(conventional hbitumen, hemulsion, hrubberized hbitumen…),

haggregate hcharacteristics, htemperature, hconstruction hetc

This hstudy his hconducted hto hevaluate hthe hadhesion hperformance hbetween

hemulsion hbinders hand haggregate hfrom h5 hsources hin hCambodia hand hto hinvestigate

hwhether hany hfactors hor hconditions hcan heffect hon hCambodia hchip hsealing. hAlso hwe

hare hgoing hto hinvestigate hwhether hany htest hmethod his hsuitable hfor hchip hseal hquality

hcontrol hin hthe hfuture hin hCambodia, hand halso hthis hstudy his ha hkey hto himprove

hCambodian hchip hseal hspecifications hbecome hmore heffective

DECLARATION OF AUTHORSHIP

I, Duk Heng, the author of this thesis declare that to the best of my education, this thesis entitled “A Study on Adhesion between Emulsion and Mineral Aggregates from Various Sources Applying in Chip Seal in Takeo Province, Cambodia” is my own original work Any ideas, any quotes or any materials from the works of other authors included in my thesis or from other published documents are fully acknowledged according to the standard referencing practices This thesis is now in progress of submitting for the Master ldegree in Transportation lEngineering in Hochiminh lCity University of lTechnology This thesis has never been submitted in the past for an award of any certification or any degree in any other school yet

Hochiminh city, Feb 24, 2020

DUK HENG

CONTENTS

ACKNOWLEDGEMENT iii

SUMMARY v

DECLARATION OF AUTHORSHIP vi

CONTENTS vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF EQUATIONS xiv

LIST OF ABBREVIATIONS xv

CHAPTER 1: INTRODUCTION 1

1.1 BACKGROUND 1

1.2 PROBLEMS STATEMENT 1

1.3 OBJECTIVES OF THIS STUDY 3

1.4 OUTLINE 3

CHAPTER 2: LITERATURE REVIEW OF CHIP SEAL 4

2.1 CHIP SEAL DEFINITION 4

2.2 THE ADVANTAGES OF CHIP SEAL 7

2.3 CHIP SEAL MATERIALS SELECTION 8

2.3.1 Aggregate uses in chip seal 8

2.3.1.1 Aggregate types 8

2.3.1.2 Aggregate application rate 8

2.3.1.3 Aggregate shape 8

2.3.1.4 Aggregate gradation 10

2.3.1.5 Dusty aggregate 11

2.3.2 Chip seal binders 12

2.3.2.1 Cutback asphalts 12

2.3.2.2 Asphalt emulsions 13

2.3.2.3 The benefits of asphalt emulsion binders 17

2.3.2.4 How to store and handling the asphalt emulsions 17

2.4 CHIP SEAL DESIGN THEORY 18

2.5 CONSTRUCTION OF CHIP SEAL 19

2.5.1.1 Environmental conditions 19

2.5.1.2 Emulsion binder application 19

2.5.1.3 Application of cover aggregate 20

2.5.1.4 Rolling operation 20

2.5.1.5 Sweeping after rolling 21

2.5.1.6 Traffic control 21

2.5.1.7 Removing traffic control 21

2.6 CHIP SEAL DISTRESSES 22

2.6.1 Bleeding (flushing) 22

2.6.2 Raveling 22

CHAPTER 3: STUDY DESIGN AND METHODOLOGY 25

3.1 MATERIALS 25

3.1.1 Aggregate chips 25

3.1.2 Asphalt binders 29

3.2 EXPERIMENTAL AND TEST METHOD 30

3.2.1 Sweep test ASTM D7000 30

3.2.1.1 Summary of Sweep test 30

3.2.1.2 Significance and use 30

3.2.1.3 Apparatus 30

3.2.1.4 Materials 33

3.2.1.5 Procedure 34

3.2.1.6 Calculation 36

3.2.2 Vialit test BS EN 12272-3 37

3.2.2.1 Summary of test method 37

3.2.2.2 Significance and use 37

3.2.2.3 Apparatus 38

3.2.2.4 Materials 40

3.2.2.5 Procedure 40

3.2.2.6 Calculation 41

3.2.3 Test method for determining field coating TCVN 8817-15:2011 41

3.2.3.1 Summary test method 41

3.2.3.2 Apparatus 42

3.2.3.3 Procedure 43

3.2.4 Digital image analysis 43

3.2.4.1 Summary of test method 43

3.2.4.2 Apparatus 44

3.2.4.3 Software 44

3.2.4.4 Procedure 44

3.2.4.5 Output result 46

CHAPTER 4: RESULTS AND DISCUSSION 48

4.1 PERFORMANCE FROM SWEEP TEST 48

4.2 PERFORMANCE FROM VIALIT ADHESION TEST 51

4.3 PERFORMANCE FROM TEST METHOD FOR DETERMINING FIELD COATING AND IMAGE ANALYSIS APPLICATION 55

4.4 CORRELATIONS BETWEEN AGGREGATE AND TEST METHODS 59 CHAPTER 5: CONCLUSIONS AND RECOMMENDATION 60

5.1 SUMMARY RESULTS AND CONCLUSIONS 60

5.2 CONTRIBUTION AND RECOMMENDATION 61

REFERENCES 63

ABOUT AUTHOR 65

LIST OF TABLES

Table 2.1 The properties and grades of cutback asphalt [4] 13

Table 2.2 The grades of anionic emulsified asphalt [4] 14

Table 2.3 The grades of cationic emulsified asphalt [4] 14

Table 3.1 Aggregate characteristics from 5 sources in Cambodia 25

Table 3.2 CRS-1 emulsion binder characteristics 29

Table 3.3 CRS-2 emulsion binder characteristics 29

Table 3.4 Brush dimensions for sweep test 31

Table 3.5 Amount of aggregate used in Sweep test (50/50 blend aggregate) 34

Table 4.1 The significant efffect in Sweep test 51

Table 4.2 The significant effects in Vialit test 53

Table 4.3 The significant effects in Image analysis 56

Table 4.4 Correlations between aggregate characteristics and each test methods 59

LIST OF FIGURES

Figure 1.1 Bleeding on Route 48, Koh Kong province (Cambodia) 2

Figure 1.2 Raveling on Route 110, Kandal province (Cambodia) 2

Figure 2.1 A completed single chip seal 4

Figure 2.2 Spraying bituminous material 5

Figure 2.3 Application of aggregates 5

Figure 2.4 Rolling to embed chip into binder 6

Figure 2.5 Traffic causes flat chips in the wheel path to lay down on their flattest side Wood, et al [4] 9

Figure 2.6 Traffic has little effect on cubical aggregate Wood, et al [4] 10

Figure 2.7 Cross section of a one-size seal coat aggregate 11

Figure 2.8 Cross section of a graded seal coat aggregate [4] 11

Figure 2.9 Cationic asphalt emulsion before breaking [4] 16

Figure 2.10 Cationic asphalt emulsion beginning to break [4] 16

Figure 2.11 Chip seal bleeding in Cambodia 23

Figure 2.12 Raveling example in Cambodia 24

Figure 3.1: Kho Ek Tum aggregate quarry, Kampong Speu province 26

Figure 3.2: Pech Mony aggregate quarry, Kampong Speu province 26

Figure 3.3: Los Angeles Abrasion test accordings to ASTM C131 27

Figure 3.4: Sieve analysis test accordings to ASTM C136 27

Figure 3.5: Bulk specific gravity accordings to ASTM C127 28

Figure 3.6: Flakiness and elongation index accordings to ASTM D4791 28

Figure 3.7 Mixer Hobart 31

Figure 3.8 Strike off plate 32

Figure 3.9 Compactor in Sweep test 33

Figure 3.10 Sweeping procedure 36

Figure 3.11 Flat steel plate 38

Figure 3.12 3-pointed supports 39

Figure 3.13 Climatic chamber 39

Figure 3.14 Vialit shock test procedure: a) fabricated specimens; b) Vialit apparatus balancing; c) Chips dropped after Vialit shocked 41Figure 3.15 Test method for determining field coating: a) pan and ladle; b) graduated cylinder; c) metal cup 42Figure 3.16 Test method for determining field coating procedure: a) Preparing aggregate and emulsion b) mixing the mixture c) rinsing the mixture 43Figure 3.17 Specimen image taking 45Figure 3.18 Image analysis processing in Fiji 46Figure 3.19 Image segmentation: a) image before segmentation; b) image after segmentation in Fiji software 46Figure 3.20 Output result of digital image analysis 47Figure 4.1 Mass loss percentage by Sweep test in each combination of aggregates and emulsion binders 48Figure 4.2 Regression line between Mass loss and Flakiness index in Sweep Test 49Figure 4.3 Regression line between Mass loss and Absorption in Sweep Test 49Figure 4.4 Regression line between Los Angeles Abrasion in Sweep test 50Figure 4.5 Regression line between BSG and mass loss in Sweep test 50Figure 4.6 Adhesivity value by Vialit Shock test in all combination of aggregates and CRS-1 emulsion 52Figure 4.7 Adhesivity value by Vialit Shock test in each combination of aggregates and CRS-2 emulsion 53Figure 4.8 Regression line of Flakiness index and adhesivity value 54Figure 4.9 Regression line of water absorption and adhesivity value 54Figure 4.10 Aggregates coated area by Test method for determining field coating -Digital image 56Figure 4.11 Regression line between flakiness indexes with aggregate coated areas in TCVN 8817-15 57Figure 4.12 Regression line between absorption rates with aggregate coated areas in TCVN 8817-15 58

Figure 4.13 Regression line between BSG with aggregate coated areas in TCVN 8817-15 58

LIST OF EQUATIONS

(1) Aggregate amount for Sweep test 33(2) Mass loss calculation 36(3) Adhesivity value 41

LIST OF ABBREVIATIONS

AASHTO American Association Of State Highway And Transportation Officials

AC Asphalt Cement

ASTM American Society For Testing And Materials

BKU Bach Khoa University

BS British Standard

BSG Bulk Specific Gravity

CRS Cationic Rapid Setting

HFMS High Float Medium Setting

HFRS High Float Rapid Setting

HMA Hot Mix Asphalt

LA Los Angeles Abrasion Test

PMN Near Pech Mony

PWTTD Public Works And Transport Technical Department

TRH3 Technical Recommendations For Highways 3

TWS Trainable Weka Segmentation

VFA Void Between Aggregates Filled With Asphalt VMA Void Contend Between Aggregates

CHAPTER 1: INTRODUCTION

1.1 BACKGROUND

A hchip hseal hor ha hseal hcoat his hbasically ha hcombination hof ha hsingle hlayer hof

hasphalt hbinder hthat his hcovered hby ha hlayer hof hembedded haggregate. hThe hprimary

hpurpose hof hchip hseal his hto hseal hthe hfine hcracks hin hthe hunderlying hpavement’s

hsurface hand hto hprevent hthe hpavement hfrom hwater hintrusion hinto hthe hbase hand

hsubgrade. hThe hrole hof haggregate his hto hprotect hthe hasphalt hlayer hfrom hdamage hand

hanother hone his hto hincrease hskid-resistant hsurface hfor hvehicles h[1]

Chip hseals hare hone hof hthe hmajor hpavement hpreservation htools hthat hused hto

hextend hthe hservice hlives hof hpavements hacross. hSuccessful happlication hof hchip hseals

hare hdependent hon hthe hmethods hemployed hin hthe hfield hduring hconstruction

hAdditionally, hcompatibility hbetween haggregates hand hbinders his himportant hto hensure

hthat hadequate hadhesion his hachieved. hMost hof hthe hresearch hin hchip hseal hfield hhas

hfocused hmuch hon hmaterial hscience haspects hof heither hthe hasphalt hbinders hor hthe

haggregate, hbut hthere hare hvery hlittle hhas hbeen hwritten habout hcombinations hof hbinder

hand haggregate. hRaveling hor hloss hof haggregate hand hbleeding hare htwo hcommon htypes

hof hdeterioration hchip hseals hthat hoccur hcause hof ha hweak hbond hbetween hthe hasphalt

hbinder hand hthe haggregate. hTherefore, hthe hinteraction hbetween hemulsion hbinder hand

haggregate hwill hbe hinvestigated hin hthis hstudy hto hevaluate hthe hadhesion hperformance

hof hchip hseals

1.2 PROBLEMS STATEMENT

Some deteriorations of chip seal are usually encountered in chip seal project Bleeding or flushing is a common type of deterioration in the chip seals as illustrated

in Figure 1.1 This type of deterioration is occurs by the hot weather and utilizing an

over amount of asphalt binder on chip seal Another deterioration in chip seals is

raveling or loss of aggregate (see Figure 1.2) Raveling usually occurs when the

aggregate and binder adhesion bond become weaker due to some parameters, such as traffic, climate and aggregate properties etc

According to report from Road Infrastructure Department (RID) of Ministry of Public Works and Transport in 2016, Cambodia has 6,626.777km paved roads 81.84% (5,423.334km) of the paved roads were paved by chip seals [2] because of its cost effectiveness, convenience in construction and suitable for developing country with low and medium traffic

Figure 1.1 Bleeding on Route 48, Koh Kong province (Cambodia)

Figure 1.2 Raveling on Route 110, Kandal province (Cambodia)

The performance of chip seals depends to a great extent on the effectiveness of the aggregate-binder bond Unlike hot-mix asphalt in which the aggregate particles are fully coated and protected by the binder, the seal coat system, which is only one aggregate thick, has to rely on the bonding established by a partial coating of the aggregate surface (approximately 30-50% of the aggregate surface area) by the bituminous binder An adequate bond between the aggregate and binder will be a key

to get better chip seals, then we can minimize the occurrence of problems in chip seals especially the loss of aggregate or raveling Moreover, a better aggregate and binder bond will help the designers to reduce the use of binder quantities This lead

to reduce the binder cost and also reduce the bleeding problems [3]

1.3 OBJECTIVES OF THIS STUDY

The objectives of this study are listed below:

 To investigate the adhesion performance between aggregate from 5 different sources in Cambodia with 2 types of emulsion binders conduct Sweep test, Vialit test and Test method for determining field coating

 Investigate Digital image analysis on Test method for determining field coating

 Investigate the correlation between above tests using in chip seals

 Evaluate the performance of chip seals in Cambodia base on the results from this study

1.4 OUTLINE

This study is structured according to the following categories:

 Chapter 1: Introduction

 Chapter 2: Literature review

 Chapter 3: Study design and methodology

 Chapter 4: Results and discussion

 Chapter 5: Conclusions and recommendation

CHAPTER 2: LITERATURE REVIEW OF CHIP SEAL

2.1 CHIP SEAL DEFINITION

A chip seal or a seal coat or a surface treatment or a surface dressing or a sprayed seal, it involves by spraying a layer of asphalt binder on the surface of an

existing pavement followed by an application of a cover aggregates (Figure 2.1) The

asphalt binder is usually emulsion (suspended in water) to allow for it to be applied without the addition of extreme heat The aggregate in chip seal is normally gravel or crushed aggregate such as granite, quartzite or trap rock (basalt) [4] Chip seals are constructed by spraying the asphalt material with a distributor truck followed by the aggregate (chip) spreader that spreads a single layer of aggregate to form a sealing

surface (Figure 2.2, Figure 2.3) After the application of the aggregate, the rollers are used to embed the chips into the binder surface (Figure 2.4) [5]

Figure 2.1 A completed single chip seal

The chip seal offers significant advantages, primarily as an economical and efficient means to provide skid resistance and fast construction Generally, the cationic rapid setting (CRS) type of emulsion is the most commonly used asphalt binder for chip seals Chip seals have cost effective due to their low initial costs when

we compare them with thin asphalt overlays and other factors that influence on the surface treatment selection decisions where the structural capacity of the existing pavement is sufficient to sustain its existing loads [6]

Figure 2.2 Spraying bituminous material

Figure 2.3 Application of aggregates

Chip kseals kare kbasically keffective ksurface ktreatment kin ksealing kthe kcracks

kexisting kon kpavement ksurface. kBleeding kor kflushing ksurfaces kthat kare kconsidered

kfor kchip kseal kapplications kshould kbe ktreated kcarefully kbecause kflushing kis kgenerally

kaffected kon kthe knew kchip kseal kif kthe kaggregate kand kbinder krates kare knot kdesigned

kaccordingly. kThe kbinder krates kmust kbe kdecreased kand kthe kcoarser kaggregate kshould

kbe kselected kfor kchip kseal kproject. kOne kof kthe kmost kdifficulties kin kchip kseal kdesign

kis kthe kpavement ksurface kthat kis knot kuniform k[7]

Figure 2.4 Rolling to embed chip into binder

The kbond kbetween kasphalt kbinder kand kaggregate kis ka kcombination kof

kmechanical, kchemical, kelectrostatic kand kadhesive kbonding kmechanisms. kIt kdepends

kon kboth kthe kchemical kand kphysical kproperties kof kasphalt kbinder kand kaggregate

kAggregate kproperties kthat kinfluence kon kthe kbond kbetween kaggregate kand kbinder

kinclude ksurface ktexture, ksurface kchemistry, kporosity kand kmineralogy kThe

kproperties kof kbinder kcharacteristics kinclude kchemical kcomposition kand kits kviscosity

kat kthe ktime kof kaggregate kapplication. kIn kthe kcase kof kemulsified kasphalts, kthe ktype

kof kemulsion k(cationic, kanionic) kand kit’s kbreaking kand kcuring kcharacteristics keffect

kon kthe kbonding kbetween kaggregate kand kbinder k[3]

2.2 THE ADVANTAGES OF CHIP SEAL

The kfirst kreason kto kseal kan kasphalt kpavement kis kto kdefend kthe kpavement kfrom

kthe kdeteriorating keffects kof kwater kand kambient katmosphere. kWhen kan kasphalt

kpavement kis kexposed kto kwind, ksun kand kwater, kthe kasphalt kbecome khardens kor

koxidizes. kThis kleads kthe kpavement kmore kbrittle. kAnd kafter kthat, kthe kpavement kwill

kcrack kbecause kit kis kunable kto kbend kand kflex kwhen kexposed kto ktraffic kand

ktemperature kchanges. kA kchip kseal kcorrect kthis kphenomena kby kproviding ka

kmembrane kwhich knot konly kslows kdown kthe koxidation kprocess kbut kit kalso khelps kthe

kpavement kto kresist kthe kwater kand kpreventing kthe kwater kfrom kentering kto kthe kbase

kof kpavement

Another kadvantage kof kchip kseal kis kto kincrease kthe ksurface kskid kresistance. kThis

kwork kis kaccomplished kby kthe kadditional ktexture kthat kthe kaggregate kadds kto kthe

kpavement. kBy kthe ktime, ktraffic kbegins kto kwear kthe kfine kmaterial kfrom kan kasphalt

kpavement ksurface. kThis kresults kwill klead ka kcondition kreferred kto kas kraveling kor kloss

kof kaggregate. kWhen kenough kamount kof kthe kfine kmaterial kis kworn koff kthe kpavement

ksurface, kthe ktraffic kis kmoving kmostly kon kthe kcourse kaggregate. kWhen kthese

kaggregate kbegin kto kbecome kpolished kand ksmooth, kthe kroadway kmay kbecome

kslippery kand kmaking kit kdifficult kto kstop kquickly kfor kthe kdrivers k[4]

When kwe kapplied kto kan kasphalt kpavement ksurface, ka kchip kseal kprovides ka

kdurable kbenefits kthat kall kweather ksurfacing kthat:

 Seals kan kexisting kasphalt kpavement kagainst kthe kintrusion kof kwater kand kair

 Improves kraveled ksurface

 Improves kskid kresistance

 Provides kthe kdesired ksurface ktexture

 Provides klight kreflecting kcharacteristics

 Makes kpaved kshoulders kor kother kgeometric kfeatures kto kbe kdemarcated kby

kproviding ka kdifferent ktexture kcolor

 Improve ka kuniform kappearing ksurface

The kroles kof kthe kasphalt kbinder kare kto kbind kthe kaggregate kparticles kto kstick kwith kthe

kunderlying ksurface kand kto kprovide ka kwaterproof. kThe kroles kof kthe kaggregate kare kto

kresist ktraffic kabrasion, kto ktransmit kwheel kloads kand kto kprovide kskid kresistance kand

kprovide ka kdesired ksurface ktexture k[8]

2.3 CHIP SEAL MATERIALS SELECTION

2.3.1 Aggregate uses in chip seal

2.3.1.1 Aggregate types

Chip seal aggregates are selected based on several factors such as availability, cost, the type of road being sealed and traffic volume and movement and guidelines for choosing aggregate are described below:

 Resistance to traffic wear and snow plow damage

 Effect on asphalt binder quantity

 Cost

 Resistance to turning & scuffing [4]

2.3.1.2 Aggregate application rate

The kcover kaggregate kuse kin kchip kseal kshould kbe kapplied kso kit kis konly kone

klayer kthickness, kunless ka kdouble kor kchoke kseal kis kbeing kused. kApplying ktoo kmuch

kaggregate knot konly kincreases kthe kchance kof kwindshield kdamage kto kpassing kvehicles

kbut kcan kalso kdislodge kproperly kembedded kstones. kThe kexception kto kthis kis kin kareas

kwhere kextensive kstopping kand kturning kmovements ktake kplace, ksuch kas kintersections

kand kturn klanes. k kTo kreduce kthe kscuffing kcaused kbe kvehicle ktires kturning kon kthe

kfresh kchip kseal, ka kslight kexcess kof kaggregate, kabout k5 kor k10 kpercent kshould kbe

kapplied kin kchip kseal kconstruction kprojects k[4]

2.3.1.3 Aggregate shape

The shape of an aggregate chip is characterized by:

 Cubical or flat

 Angular or round

 The effect of aggregate flatness

Traffic kplays kvery kimportant krole kin kdetermining kthe kchip korientation kof kchip

kseal kconstructed kwith kflat kand kelongated kaggregate. kThe kmore kflatter kof

kaggregate, kthe kmore ksusceptible kthe kchip kseal kwill kbe kto keither kbleeding kin kthe

kwheel kpaths kor kexcessive kchip kloss kin kthe knon-wheel kpath kareas kbecause kthe

ktraffic kwill kcauses kany kflat kchips kin kthe kwheel kpath kto klie kon ktheir kflattest kside

kThis kresults kin ka kthinner kchip kseal kin kthe kwheel kpath kthan kin kthe knon-traffic

kareas kas kshown kin kFigure 2.5. kIf kthe kbinder kis kapplied ktoo kthick kin kthe kwheel

kpaths, kbleeding kwill kresult kwhen kthe kchips klie kon ktheir kflat kside.The kchips kin

kthe knon-traffic kareas kwill kbe kdislodged kby ktraffic kand ksnow kplows kblades k[4]

Figure 2.5 Traffic causes flat chips in the wheel path to lay down on their flattest

side Wood, et al [4]

On klow kvolume kroadways kand kparking klots, kthe kdifference kin kchip kseal

kthickness kmay knot kbecome ka kproblem kbecause kit krequires krepeated kapplications kof

ktraffic kto kreorient kthe kchips kon ktheir kflattest kside. kIf kthe ktraffic kvolume kis klow

kenough, kor knot kconfined kto ka kspecific karea, ksuch kas ka kwheel kpath, kthere kmay knot kbe

ka klarge kenough kdifference kin kchip kheight kto kcause ka kproblem. kWith kcubical

kaggregate, ktraffic kwill knot khave ka kpronounced keffect kon kchip korientation. kNo

kmatter khow kthe kchips kare koriented, kthe kseal kcoat kheight kwill kbe kessentially kthe

ksame kand kchip kembedment kwill kbe kuniform Aggregate with flakiness index over 30 percent should not be used for chip seal On high volume roadways, the flakiness index should not exceed 20 percent [4]

Figure 2.6 Traffic has little effect on cubical aggregate Wood, et al [4]

 The effect of aggregate roundness

The kroundness kof kthe kaggregate kdetermine khow kresistant kthe kchip kseal kwill kbe

kto kturning kand kstopping kmovements. kRound kaggregates kare kmuch kmore

ksusceptible kto krolling kand kdisplacement kby ktraffic kthan kangular kaggregates

kwhich ktend kto klock ktogether kbetter. kBecause kof ktheir kshape, kit kis kvery kdifficult

kto kachieve kthis ksame kresult kwith kround kaggregate kunless kthe kaggregate kis

kextremely kgraded. kThe kgraded kaggregate kwill kallow kthe ksmaller kstones kto kfill kin

kthe kareas kbetween kthe klarger kones [4]

2.3.1.4 Aggregate gradation

Aggregate kgradation kplays kan kimportant krole kin kchip kseal kdesign, kconstruction

kand kperformance. kGradation khere, krefers kto kthe kdistribution kof kthe kvarious ksized

kstones kthat kmake kthe kaggregate kmatrix. kAggregates kused kin kchip kseal kconstruction

kare knormally kclassified kas keither kone ksize kor kgraded

 One-size aggregate

The best chip seal gradations are those that are essentially one-size An aggregate

is considered one-size if nearly all of the material is retained on two consecutive sieves This results in most of the stone pieces being in a narrow range of sizes as

shown in Figure 2.7

Figure 2.7 Cross section of a one-size seal coat aggregate

All of the aggregate chips are fairly close to the same size Also, we noticed that the large amount of space (voids) that exists between each stone This is the space available for the asphalt binder to fill and a key component in determining the amount

of binder required for good performance of chip seal

 Graded aggregate

Graded aggregates cover a wide range of possibilities from dense graded to gap graded The more graded an aggregate is, the less desirable it will be for chip seal, because graded aggregates have lower air voids, there is less room to fit the binder in between the chips And the result, there is a fine line between applying too much binder (lead to bleeding) and not enough (lead to raveling) [4]

Figure 2.8 Cross section of a graded seal coat aggregate [4]

2.3.1.5 Dusty aggregate

Dusty aggregates should not be used for chip sealing unless certain precautions are taken To avoid dusty aggregate, the specified aggregate gradation should have 1 percent or less passing the #200 sieve (75 µm) When dust coat the outside of the aggregate particles, it prevents them from bonding with the asphalt binder and lead

to chip loss [4]

2.3.2 Chip seal binders

The asphalt binder is used in road applications because it is waterproof and can adheres to stone At room temperature, most asphalts are very stiff, too stiff to apply

to a roadway To get it into a form that can be applied requires the viscosity to be reduced and this can be reduced by:

 Heating the asphalt binder

 Making it as a cutback asphalt

 Making it as an asphalt emulsion

Cutback asphalts and asphalt emulsions are two method that often used in chip seal construction [4]

2.3.2.1 Cutback asphalts

Cutback asphalts (or liquid asphalts) are the asphalts that are dissolved in a petroleum solvent (or cutter) There are two typical solvents include naphtha (or gasoline) and kerosene The type of solvent controls the curing time of the cutback and thus when it will obtain its ultimate strength Rapid curing cutbacks use naphtha while medium curing cutbacks use kerosene The amount of cutter affects the viscosity of the cutback asphalt The higher the cutter content, the lower the viscosity and the more fluid it will be The use of cutbacks asphalt has declined over the years because of the concerns over pollution and health risks as the solvents evaporate into the atmosphere The advantage of cutbacks have over emulsions is a much higher residual asphalt percentage, over 80 percent With asphalt emulsions, there is just over 65 percent of residual asphalt

Cutbacks are divided into two classifications, Rapid-Curing (RC) and Curing (MC), and they are depending on the solvent used They are further defined

Medium-by a number which indicates the minimum kinematic viscosity (fluidity) of the cutback The lower the number, the more fluid the cutback is The shaded grades in Table 2.1 are the ones typically used for seal coating [4]

Table 2.1 The properties and grades of cutback asphalt [4]

2.3.2.2 Asphalt emulsions

The phenomena that occurs when you mix two incompatible components together called emulsion Emulsions are made up of two components with one dispersed in the other To maintain the dispersion requires some way of overcoming the lack of compatibility An asphalt emulsion consists of asphalt particles that dispersed in water and chemically stabilized and the only thing between the asphalt particles is water and the emulsifier Actually, asphalt is not soluble in water that keeping it dispersed in fine particles is a significant feat Emulsions are divided into

3 grades for classification: cationic, anionic and non-ionic In chip seal construction, only the first two types are used in roadway construction and maintenance The cationic and anionic designation refers to the electrical charge of the emulsifier surrounding the asphalt particles Cationic emulsions have a positive electrical charge surrounding the asphalt particles while anionic emulsions have a negative electrical charge Since opposite electrical charges attract, anionic emulsions should be used with aggregates having a positive charge Similarly, cationic emulsions should be

used with aggregates having a negative charge Failure to use materials with opposite electrical charges may result in the materials repelling each other, causing failure [4]

Table 2.2 The grades of anionic emulsified asphalt [4]

Table 2.3 The grades of cationic emulsified asphalt [4]

In addition to being classified by their electrical charge, emulsions are further classified according to how quickly they will revert back to asphalt cement The terms

RS, MS and SS have been adopted to simplify and standardize this classification They are relative terms only and stand for Rapid-Setting, Medium-Setting and Slow-Setting As the emulsifier is drawn toward aggregate surfaces with an opposite

electrical charge, the asphalt particles begin to settle to the bottom of the emulsion The speed at which this occurs is indicated by the RS, MS and SS designation Emulsions are subdivided by a series of numbers that relate to the viscosity of the emulsion and the hardness of the base asphalt binder The numbers of “1" and “2" are used to indicate the viscosity of the emulsion When the lower the number is, the lower the viscosity and the more fluid the emulsion is If the number is followed by the letter “h” then the emulsion has a harder asphalt binder [4]

 The properties of asphalt emulsion binders

The properties of emulsions and their behavior under various conditions are related

to the type and the strength of emulsifier used in them “Breaking” refers to the phenomena that the asphalt and water separate from each other This happens when the emulsifier leaves the surface of the asphalt binder particles due to its attraction to the surface of the aggregate Since asphalt is heavier than water, the asphalt particles will down to the bottom of the solution Since anionic emulsions have a negative charge, as does almost every mineral, there will be no electrostatic attraction between the emulsion and the aggregate surface since like charges push each other For an anionic emulsion, to break the particles must get so close to each other that the pushing forces are overcome by the attractive forces that exist between all them In chip seal, this occurs as the water evaporates out of the emulsion Cationic emulsions have a positive charge and since opposite charges attract, they are drawn toward most aggregate particles Therefore, a direct and very rapid reaction between the emulsion

and an aggregate or pavement is possible as shown in Figure 2.9 and Figure 2.10

The size of the charge, effects on the stability, the larger the charge, the more rapid the reaction can be The other mechanism which effects on the curing is evaporation After the chemical break is completed, the water must still be completely evaporated for the residual asphalt binder to success a full strength [4]

Figure 2.9 Cationic asphalt emulsion before breaking [4]

Figure 2.10 Cationic asphalt emulsion beginning to break [4]

 Polymer modified emulsion binders

The properties of asphalt emulsion binders can be enhanced by the addition of polymer binders Simple polymers used in emulsions are natural and synthetic latex, SBR and SBS polymers Usually, around 2.5% to 3% polymer by weight is added to the emulsion binder Some benefits of using polymer binders are:

 Increased the viscosity of the residual asphalt that can minimize bleeding

 Increased early stiffness

 Improve the flexibility

Anyhow, the main disadvantage of using polymer modified emulsions is the additional cost in chip seal project Modified emulsions usually cost 30 percent more than original emulsions [4]

2.3.2.3 The benefits of asphalt emulsion binders

The main benefits of using emulsions rather than cutback asphalts can be summarized cause of pollution control and safety factor

 About the pollution control

Actually, kerosene and gas fumes are greenhouse gases So in a cutback, they will evaporate into the air and become pollutants [4]

 About the safety

During the emulsions are based on water, so they have no flash point and will be not flammable or explosive When it’s based on water, emulsions will not make any health risk to people [4]

2.3.2.4 How to store and handling the asphalt emulsions

 Pumping

Pumps mean to compress or to shear the material that they pump This will lead the emulsion being compressed And if it happens too severely or too often the emulsion will become coarser and will be back to the original asphalt cement Pumps should

be selected very carefully [4]

 Temperature

When materials get cold they become shrink For an emulsion, it means that the asphalt droplets will get closer together Then, when the emulsion becomes too cold, the asphalt particles can will get too close together and will cause the emulsion to back to the original asphalt cement When the materials become hot then they will expand And for an emulsion, heating is a useful method However, when water gets hot, its evaporation rate will increases When the water leaves the emulsion, the asphalt droplets become closer to each other and will back to original asphalt cement

When any part of the emulsion gets hot more than (95 0C), localized boiling may occur and cause the droplets become original asphalt cement [4]

 Cleaning

Cleanliness is very important for emulsions If the emulsion get in touched with air it will begin to break And for a cationic emulsion, when it comes into contact with metal it also can begin to break To get a higher the performance of the emulsion, the more cleaning of emulsion will be needed [4]

2.4 CHIP SEAL DESIGN THEORY

The kchip-seal kdesign kmethods kis kfound kby kHanson k[9] kand kKearby k[10]

kprovided kthe kbasis kfor knowadays kand kfuture kdesign kmethodologies. kFrom kthe

koriginal kHanson kmethod kconcepts kdevelop kthe kMcLeod kprocedure k[5, 11] kthat kwas

kadopted kby kthe kAsphalt kInstitute kand kthe kAustroads kand kthe kSouth kAfrican

kmethods. kThe kKearby kmethod kwas klater kimproved k[12, 13] kand kthen kadopted kby

kTexas. kThe kUK kdesigned ksurface kdressings kor kchip kseals kused kfew kof kthe kHanson

kconcepts kcombined kwith kideas kof kJackson k[14]. kThe kmain kpurpose kof kchip kseal

kdesign kis kto kselect kthe kaggregate kand kthe kasphalt kemulsion kbinder kapplication krates

kthat kwill kcause kthe kin ka kdurable kpavement kchip kseal. kThe kquantity kof kasphalt

kbinder krequired kwill kdepends kon kthe kshape, ksize, kand korientation kof kthe kaggregate

kparticles, kthe kembedment kof kaggregate kinto kthe ksubstrate, kthe ktexture kof kthe

ksubstrate, kand kthe kabsorption kof kasphalt kbinder kinto keither kthe ksubstrate kor

kaggregate. kThis kdesign kmethod kis kactually kbased kon kthe kfollowing kassumptions kfor

kaggregate, ktraffic, kand kembedment

 Aggregate: kone-sized kaggregates kwith ka kflakiness kindex kof k15% kto k25%

 Traffic: k10%, kor kless, kheavy kvehicles

 Embedment: k50% kto k65% kchip kembedment kafter ktwo kyears

The kearly kapplication kof ksurface ktreatments klike kchip kseals kappear kto khave kused ka

kpurely kempirical kapproach kto ktheir kdesign. kChip kseal kdesign kinvolves kthe

kcalculation kof kcorrect kamounts kof kasphalt kbinder kand kaggregate kto kbe kapplied kover

ka kunit karea kof kthe kroad kpavement. kThe kmain kimportant kfactors kof kchip kseal kdesign

kprocess kare kthe ktypes kand kamounts kof kthe kasphalt kbinder kand kaggregate kto kuse. kThe

kaggregates kused kin kchip kseal krole kto ktransfer kthe kwheel kload kto kthe kunderlying

ksurface kand kto kprotect kthe knew kseal kfrom kabrasion kby ktraffic. kMoreover kthe

kaggregate kalso kimprove kthe kskid kresistant ksurface kby kproviding kenhanced ksurface

kdrainage, kwhich kin kturn kreduces kthe kprobability kof khydroplaning kphenomena [15]

2.5 CONSTRUCTION OF CHIP SEAL

2.5.1.1 Environmental conditions

On ka kwet kpavement ksurface, kwhile krain kwill kbe kimminent kor kduring kthe khigh

kwind kspraying kshould knot kbe kcarried kout k[16]. kThe ktemperature kof kpavement kfor

kchip kseal kapplications kshould kbe ka kminimum kof k21 k°C kwithout kor kvery klittle kwind

kHowever, kchip kseal kapplication kshould kbe kstarted kbefore kthe kpavement ktemperature

kreaches k21 k°C kas klong kas kthe kpavement ktemperatures kare kexpected kto kbe k21 k°C kand

krise kwithin k60 kminutes kafter kstarting kthe kwork. kWind kspeeds kin kexcess kof k20 kmph

ktransverse kto kthe kpavement kalignment kcan kblow kasphalt kemulsion konto kopposing

ktraffic kon ktwo klane kfacilities, ktherefore kchip kseal koperations kshould kbe kavoided

kunder kthese kconditions. kChip kseal kshould knot kbe kpursued kif kit kis kraining. kA krain

kstorm kcould kwash kthe kasphalt kemulsion konto kconcrete kgutters kor kinto kroadside

kditches. kAmbient kair ktemperatures kin kexcess kof k43 k°C kwith kthe ksun kshining kor kwith

kmedium kwind kcan kcause kthe kemulsified kasphalts kto kform ka kskin kon kthe ksurface

ksuch kthat kthe kemulsion kdoes knot kset kadequately. kTo kcorrect kthis ksituation kmay

krequire kthe kspread kof kchips kcloser kto kthe kdistributor kto kobtain kproper kembedment

kHowever, khigh kair ktemperatures kmay klead kto klower kviscosity kemulsion kresidue,

kresulting kin khigher kpotential kfor kpick kup kon krubber ktire krollers, ktherefore,

kincreasing kthe kdemulsibility kof kanionic kemulsion kbinders kmay khelp kremedy kthis

ksituation[17]

2.5.1.2 Emulsion binder application

For kemulsion kbinder kapplication, kthe kdistributor koperator kshould kposition kthe

kspray kbar kat kthe krear kof kthe kpaper kon ktakeoff kso kthat kthe kbar kreaches kthe kpavement

kthe kdistributor kspeed kis kappropriate kfor kthe kdesired kspray krate. kSpraying kshould kbe

kstopped kwhen kthe kspray kbar khas kpassed kover kthe kpaper. kWhen kapproximately k90%

kof kthe kdistributor kvolume khas kbeen ksprayed kis ka knice kmethod kto kdetermine kthe

kdistance kwhere kthe ksecond kstrip kof kroofing kpaper kshould kbe kplaced[18]

2.5.1.3 Application of cover aggregate

Chips kshould kbe kapplied kto kthe ksurface kof kthe kfresh kemulsion kbefore kit

kbegins kto kset kbut knot knecessarily kimmediately kafter kspraying. kIf kthe kchips kare

kapplied ktoo kearly, kthere kis krisk kthat kthe kchips kwill kroll kover kin kthe kemulsion kdue kto

kmomentum kcreated kby kthe kforward kmovement kof kthe kchip kspreader. kThus, kless

kbinder kwill kbe kavailable kto khold kthe kchips kin kplace kand kthe kexposed kbinder

kbecomes ksusceptible kto kbeing kpicked kup kon kroller ktires. kTherefore, kthe kadhesive

kquality kof kthe kemulsion kshould kbe kchecked kto kdetermine kwhen kto kapply kthe kchips

kThis kmay kbe kdetermined kby kthrowing ka khandful kof kchips konto kthe kemulsion kand

kobserving kwhether kthey kstick kto kthe ksurface kor ktend kto kroll kover. kSome

kexperimentation kis knecessary kto kestimate kthe kproper ktiming, kwhich kcan kbe

kaccomplished kduring kthe kfirst kdistributor kapplication. kIn kmany kcases, kchanges kin

kenvironmental kconditions kduring kconstruction kwill krequire kthis ktest kbe krepeated

kduring kthe kday kbecause khumidity, kchip kmoisture, kemulsion kproperties, kand kambient

kair ktemperature kaffect kthe kadhesive kquality kof kthe kemulsion [18]

2.5.1.4 Rolling operation

Some kdifferent ktypes kof krollers khave kbeen kused kto kembed kthe kchips kon kchip

kseals. kPneumatic krollers ktend kto kpick kthe kchips kup kcause kthe kaffinity kof kasphalt

kresidues kwith krubber ktires. kAnyway, kthese krollers kis kbetter kthan ksteel kwheeled

kroller kcauses kthey kdo knot kcrush kchips kin ksitu. kEven kthe klightweight ksteel krollers kof

k3 ktons kor kless kprovide ka kmeans kof kleveling kthe ksurface kof ka knew kchip kseal kafter

kpneumatic krolling, kbut kcaution kmust kbe kapplied kto kavoid kbreaking kthe kaggregate

kchips. kA krubber kcoated ksteel krollers kdrums kare kalso ka kgood kchoice kfor kembedding

kchips. kHowever, kany krigid kdrum kroller kwill klink kover kareas kof kthe kpavement kwith

kpermanent kdeformation kand kmake kthese kareas kto kbe kinadequately krolled. kNotice

kthat krollers kmust kbe kable kto kpreserve kboth kthe kdistributor kand kchip kspreader kand

kprovide kenough kpasses kto kembed kthe kaggregate kchips. kIf kthe krollers ktravel ktoo kfast,

kthen kthe kembedment kwill kbe kunsuccessful. kThat kis kwhy kthe knumber kof krollers kused

kwill kdepends kon kroller kwidth, kroller kspeed, kdistributor kand kchip kspreader kspeed kand

kthe knumber kof kpasses krequired kto kachieve kembedment ksuccessfully. kWhen kthe

krollers kmove kfaster, kthe kmore krollers kwill kbe kneeded kto kachieve kembedment kfor

kchip kseals [18]

2.5.1.5 Sweeping after rolling

Light kbrooming kshould kbe kcarry kout kas ksoon kas kpossible kafter krolling kand

kbefore kallowing kthe ktraffic kon kthe ksurface kto kremove kany kexcess kand kloose kchips

kAnd kthis kshould kbe kpossible kwhen kthe kmoisture kcontent kof kchip kseal kreaches kto kthe

klevel kthat k10% kchip kloss khappens kafter kthe ksweep ktest kin klaboratory. kThis kmoisture

kcontent, kmeasured kby kthe kmoisture kloss ktest kthat kwas kfound kto kbe kapproximately

k15% k- k25% kof kthe ktotal kmoisture kpresent kin kchip kseal kand kit kindicated kthat ktotal

kmoisture kconsists kof kwater kin kthe kemulsion kbinder kplus kmoisture kin kthe kaggregate

kchips. kMoisture kcontent kof kchip kseal kshould kbe kmeasured kin kareas kof kthe kproject

kthat kthe kmoisture kloss kis kexpected kto kbe kleast krapid ksuch klike ka kcooler kor kshady

klocations. kTo kavoid kdamaging kto kthe kfresh kchip kseal kthen kusing kvacuum kbrooms kor

kpush kbrooms kwith knylon kbristles kshould kbe kapplied kwith kmuch kcare [18]

2.5.1.6 Traffic control

Traffic may be allowed on the fresh chip seal after initial sweeping if the speeds can be controlled to less than 20 mph using the pilot vehicles It should not be allowed traffic on the new seal until final sweeping has been completed if the speeds cannot be controlled to this speed vehicles [18]

2.5.1.7 Removing traffic control

The traffic control may be removed and then the vehicular traffic will be allowed

on the fresh chip seal after brooming has been completed to remove excess or loose chips And the moisture content of the chip seal reaches the level that results in less than 10% chip loss after the sweep test in laboratory [18]

2.6 CHIP SEAL DISTRESSES

Some of the most serious distresses in chip seals are:

 Bleeding or flushing

 Raveling or aggregate loss

2.6.1 Bleeding (flushing)

When too much asphalt binder used during the construction of chip seals is one

of the simplest deterioration in chip seals The excess asphalt binder radiates upward onto the pavement surface and is the origin of the black and frequently gum surface condition referred to as flushing, bleeding, or fattening up and which can lead to a

loss of skid resistance The picture from Figure 2.11 shows a case of a flushed chip

seal surface roadway

Every element in the finished highway (width, alignment, profile) satisfies both engineering and aesthetic demands, and yet the surface is the most obvious part of the structure An inadequate designed and constructed chip seal begins its service life cycle with an imperfect appearance and a surface that may have bleeded so badly and

it will reveal a loss of skid characteristics Therefore, the completed surface fulfils neither the inventive nor the rudimentary engineering requirements that the public has a right to imagine The utilization of inadequate asphalt binder leads to a raveling

of aggregate because not enough asphalt binder has been applied to glue the aggregate particles into place Occasionally the surface on where a chip seal or a surface dressing is executed is too porous or open that makes a large part of the asphalt binder immerses into it Inadequate of asphalt binder remains on top of surface is to hold the aggregate chips and it might be dislodged by traffic easily But the utilization of too little asphalt binder shows less frequently than the application of too much one [8] 2.6.2 Raveling

There are some basically main factors of the loss of aggregate or raveling from

surface dressing or chip seals as shown in Figure 2.12 below:

 A long delay of time between spraying the asphalt binder and applying the aggregate chips and it causes the asphalt binder to become cool, hardened

 Chip seal project is too late in the season Chip seal is likely to perform better

if they are under traffic a few months before rainy season

 Lacking of asphalt binder provided to paste to the aggregate into place

 Choosing of asphalt binder for prevailing conditions not suitable

 Dust or film of moisture on aggregate chips effects on the adhesion to the asphalt binder

 Too fast to open for traffic before adhesion is fully completed

 A rainstorm happens earlier than the development of adhesion

 Applying of too much aggregate chips lead embedded aggregate to get out under traffic movement

Figure 2.11 Chip seal bleeding in Cambodia