Arya Ebrahimpour, Ph.D., P.E. Professor & Interim Chair Dept. of Civil and Environmental Engineering, Idaho State University Sustainable Pavement Maintenance.

Arya Ebrahimpour, Ph.D., P.E.

Professor & Interim Chair

Dept. of Civil and Environmental Engineering, Idaho State University

Sustainable Pavement Maintenance via Chip Sealing

Application

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Outline

I. Introduction

II. Laboratory Experiments

III. Design Methodologies

IV. Test Results

V. Conclusions and Recommendations

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I. Introduction

1. Overview

2. Objectives

3. Scope of Work

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1. Overview

What is Chip sealing?

Comparative Studies and success stories from round the world.

Cost effectiveness of chip sealing compared to other preventive maintenance techniques.

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Field Observation

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2. Objectives of the Research

a) To evaluate the effectiveness of Idaho’s existing chip seal practice.

b) To identify the reasons for the loss of aggregate from the pavement surface.

c) To study the materials used and suggest the best material to improve the chip seal practice.

d) To evaluate the performance of different kinds of binders.

e) To establish a better rational design method based on experiments performed in this project.

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3. Scope of Work

Determine the properties of aggregate.

Utilize the parameters in design calcs.

Establish a better aggregate of the six districts of Idaho

Establishing a better rational design method which suites the conditions of Idaho.

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II. Laboratory Tests

a) Sieve Analysis

b) Flakiness Index Test

c) Loose Unit Weight

d) Cleanliness Value Test

e) Vialit Tests

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a) Sieve Analysis

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b) Flakiness Index Test

%55.4100)6.45678.21(

78.21

FI

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c) Loose Unit Weight

Wt of Aggregate = 9.519 lb.

Volume of the Container =

0.1 cubic feet.

Loose Unit Wt = 9.519/ 0.1

= 95.19 lb/cubic feet

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d) Cleanliness Value Test

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e) Vialit Test

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III. Design Methodologies

1. McLeod Design Method

2. Modified Kearby Method

3. New Zealand Chip Seal Design method

4. United Kingdom Road Note 39

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1. McLeod Design Method

The amount of aggregate is determined using the formula:

A = 46.8 (1-0.4V) ×H×G×E

))011506.0(139285.1( FI

MH

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McLeod Design Method Cont’d

Amount of binder to be used is given by:

R

ASVTHB

)244.2(

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2. Modified Kearby Method

The amount of aggregate is determined by:

S

WQ 27

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2. Modified Kearby Method

The asphalt spread ratio is determined by:

S + T×V×E× 5.61 =C

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3. New Zealand Chip Seals Method

The residue asphalt content is determined:

fT e)+ALD (0.138=R

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4. United Kingdom Road Note 39

United Kingdom Road Note 39

ALDFFR )0011.0(0375.0023.0625.0

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IV. Results and Discussions

1. Median Size

2. Flakiness Index

3. Average Least Dimension

4. Loose Unit Weight

5. Void Ratio

6. Cleanliness Value Test

7. Vialit Test

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1. Median Size of the Particle

The median size varied from 0.242 inches to 0.359 inches, the lowest for District 2 and the highest for District 1.

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2. Flakiness Index Value

The flakiness index values varied from 5.44 to 21.08, the lowest for District 5 and the highest for District 2.

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3. Average Least Dimension VS M/FI

District ALD M/FI

1 0.269 2.11

2 0.175 1.14

3 0.216 2.91

4 0.217 2.83

5 0.239 5.27

6 0.278 3.11

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4. Loose Unit Weight

District 5 had the highest loose unit weight of 95.92 and District 6 had the least of 87.15.

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5. Void Ratio

District Void Ratio

1 0.449

2 0.427

3 0.450

4 0.450

5 0.412

6 0.477

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6. Cleanliness Value Index

District CV (%)

Height of Sediment (in)

1 87.57 0.44

2 79.04 0.81

3 92.21 0.27

4 90.60 0.33

5 92.32 0.26

6 88.66 0.40

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7. Vialit Test Results

The Vialit Tests

Washed Unwashed0

102030405060708090

100

Per

cent

Ret

aine

d

Washed AggregateRetention (%)

Unwashed Aggregate (%)

95.13 89.44

95.04 91.29

92.6 90.68

93.24 90.42

94.00 90.47

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Vialit Test Results Cont’d

Vialit Test for Different Binders

CRS-2R CRS-2P CRS-2L CRS-2S80

82

84

86

88

90

92

94

Binder TypeA

vera

ge o

f P

erce

nt

Ret

ain

ed CRS-2R CRS-2P CRS-2L CRS-2S

89.44 91.19 87.73 88.64

91.29 93.80 93.06 89.70

90.68 92.78 90.37 89.32

90.47 92.59 90.37 89.22

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Vialit Test Results Cont’d

Vialit Test Cured at different temperatures

-20 -10 0 10 20 30 40 50 60 700

20406080

100120

Temperature, o C

Ave

rage

of

Per

cent

Re-

tain

ed

-10 Degrees C

25 Degrees C

40 Degrees C

60 Degrees C

54.83 89.44 95.58 93.4

52.93 91.29 97.12 94.6

55.06 90.68 95.32 92.8

54.27 90.47 95.92 93.6

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7. Vialit Test Results

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Vialit Test Results Cont’d

The amount of aggregate swept for different binders

CRS-2R CRS-2P CRS-2S CRS-2L

153.7 155.8 150.8 135.9

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V. Conclusions and Recommendations

1. Conclusions

2. Recommendations

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1. Conclusions

a. M/FI factor better than ALD

b. Void Ratio and its significance in the design.

c. Effect of fines on the aggregate retention

d. Effect of different binders on Aggregate

retention.

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Conclusions Cont’d

e. Effect of different aggregate on CRS-2R

f. Effect of temperature of curing on aggregate

retention.

g. Cleanliness Value compared to Percentage fines.

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a. Using washed aggregate or aggregate with least amount of fines is recommended.

b. Using aggregate which is more round in shape and is uniform in size are preferred.

2. Recommendations

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Recommendations Cont’d

c. Quantities of binder and aggregate should be used as per calculated in the design method procedure.

d. Using Digital Imagery technique and Finite element analysis.

e. Wheel Tracking better than dropping a ball.

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Questions?