Field-Focused Superpave Validation...The Superpave design system came into existence in the...

Field-Focused SuperpaveValidation

FINAL REPORT

November 2008

By Mansour Solaimanian and Scott M. MilanderThe Thomas D. LarsonPennsylvania Transportation Institute

COMMONWEALTH OF PENNSYLVANIADEPARTMENT OF TRANSPORTATION

CONTRACT # 510401PROJECT # 009

Technical Documentation Page

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized

1. Report No. FHWA-PA-2008-009-510401-009

2. Government Accession No.

3. Recipient’s Catalog No.

5. Report Date August 2008

4. Title and Subtitle Field-Focused Superpave Validation

6. Performing Organization Code

7. Author(s) Mansour Solaimanian, Scott M. Milander

8. Performing Organization Report No. LTI 2009-03 10. Work Unit No. (TRAIS)

9. Performing Organization Name and Address The Thomas D. Larson Pennsylvania Transportation Institute Transportation Research Building The Pennsylvania State University University Park, PA 16802-4710

11. Contract or Grant No. 510401, Work Order No. 9 13. Type of Report and Period Covered Final Report 7/10/2006 – 6/30/2008

12. Sponsoring Agency Name and Address Pennsylvania Department of Transportation Bureau of Planning and Research Commonwealth Keystone Building 400 North Street, 6th Floor Harrisburg, PA 17120-0064

Mid-Atlantic Universities Transportation Center The Pennsylvania State University Transportation Research Building University Park, PA 16801-4710

14. Sponsoring Agency Code

15. Supplementary Notes COTR: Mr. Tim Ramirez 16. Abstract The Superpave design system came into existence in the mid-1990s. Many pavements have been constructed with Superpave designed hot mix asphalt (HMA). Today, this technology is well established in many states. It has been over a decade since the Commonwealth of Pennsylvania began using this system for designing HMA. There has been general satisfaction with the pavements constructed with this mix, and anecdotal evidence suggests that Superpave pavements are performing well in Pennsylvania; however, within the last several years, there has been concern raised in regard to the durability of some Superpave mixes. Some have reported these problems as a result of insufficient binder content in the mix. This issue has been the driving force for several states to take measures to increase the binder content in the mix. There has also been a move by some to increase the minimum required VMA to allow more space within the aggregate structure for asphalt and therefore provide a higher binder content mix at a specified design air void level. The Pennsylvania Department of Transportation is now specifying 1/2 percent higher VMA for all aggregate-size gradations than is specified in AASHTO M323. As the Superpave design criteria are evolving, it is worth looking back into the performance of the pavements constructed with Superpave mixes. The research findings presented in this report are the result of such effort, evaluating the long-term performance of Superpave-designed mixes. 17. Key Words SuperPave, asphalt, asphalt binder, rutting, fatigue, thermal cracking, pavement performance

18. Distribution Statement No restrictions. This document is available from the National Technical Information Service, Springfield, VA 22161

19. Security Classif. (of this report) Unclassified

20. Security Classif. (of this page) Unclassified

21. No. of Pages 138

22. Price

v

TABLE OF CONTENTS

LIST OF FIGURES ...................................................................................................................... vii

LIST OF TABLES.......................................................................................................................... x

EXECUTIVE SUMMARY.................................................................................... xiii

CHAPTER ONE ........................................................................................................1

INTRODUCTION......................................................................................................1 BACKGROUND .............................................................................................................................1

Objectives ........................................................................................................................................2

Research Approach and Scope of Work ..........................................................................................3

CHAPTER TWO .......................................................................................................4

SCOPE OF FIELD AND LABORATORY INVESTIGATION...............................4 Pavement Condition Survey ............................................................................................................4

Status of Available Data for Projects Considered Under WO-43 .................................................. 4

Inventory of Materials .................................................................................................................... 5

Projects Selected for Performance Evaluation................................................................................ 6

Scope of Performance Evaluation................................................................................................... 7

Detailed Pavement Evaluation Procedure....................................................................................... 8

Transverse Profiles (Rutting).......................................................................................................... 9

Criterion to Determine Rut Depth ................................................................................................ 10

Field Seismic Modulus Testing .................................................................................................... 11

Laboratory Investigation................................................................................................................15

Preparation of Cores ..................................................................................................................... 16

Indirect Tensile Creep and Strength Testing ................................................................................ 16

Resilient Modulus Testing ............................................................................................................ 17

Asphalt-Aggregate Extraction ...................................................................................................... 20

Binder Recovery ........................................................................................................................... 21

CHAPTER THREE..................................................................................................23

ANALYSIS, INTERPRETATION, AND FINDINGS ...........................................23 Section 1: Results of Pavement Condition Evaluation .................................................................23

Evaluation Results for SR 15 Northbound, Lycoming County .................................................... 23

vi

Evaluation Results for Highway SR 11, Snyder County .............................................................. 32

Evaluation Results for SR 153-Section 225, Clearfield County....................................................37

Evaluation Results for I-80, EastBound, Centre County ...............................................................44

Evaluation Results for SR 522, SouthBound – Huntingdon County.............................................52

Rutting........................................................................................................................................... 52

Section 2: Results from Laboratory Investigation ........................................................................55

Low Temperature Creep and Strength Testing Results ................................................................ 56

Results from Resilient Modulus Testing ...................................................................................... 77

Results form PSPA Tests .............................................................................................................. 77

Analysis of Rutting Data............................................................................................................... 80

Investigation of Aging in Superpave Binders............................................................................... 83

CHAPTER FOUR....................................................................................................88

SUMMARY AND CONCLUSIONS ......................................................................88 References......................................................................................................................................91

APPENDIX A: Inventory of Data and Materials from PennDOT WO-43 Project ……… A-1 APPENDIX B: Pictures of Cores Obtained Under WO-9 ……………………………….. B-1

APPENDIX C: Scope of Pavement Condition Survey …………………………………… C-1

APPENDIX D: Aggregate Gradations Obtained from WO-9 Cores ……………………… D-1

vii

LIST OF FIGURES

Figure 1 Transverse profiling using the digital depth meter........................................................ 10

Figure 2 Approach used in this project to determine rut depth. .................................................. 11

Figure 3 Portable Seismic Pavement Analyzer (PSPA) .............................................................. 13

Figure 4 Sample PSPA data......................................................................................................... 14

Figure 5 Compression testing of the cores in diametral direction to determine indirect

tensile creep and strength...................................................................................................... 17

Figure 6 Load cycle (kN) vs. time(s). .......................................................................................... 19

Figure 7 Horizontal deformation (mm) vs. time(s)...................................................................... 19

Figure 8 Vertical deformation (mm) vs. time(s). ......................................................................... 20

Figure 9 Transverse profile at Lycoming SR 15- northbound, ID2 section. ............................... 25

Figure 10 Transverse profile at Lycoming SR 15- northbound, Superpave section.................... 26

Figure 11 Transverse profile at Lycoming SR 15- southbound, Superpave overlay section. ..... 26

Figure 12 Transverse profile at Lycoming SR 15- southbound, Superpave full section............. 27

Figure 13 Pictures of Lycoming SR 15 pavement – ID2, northbound. ....................................... 29

Figure 14 Pictures from Lycoming SR 15, Superpave full depth, northbound. .......................... 30

Figure 15 Pictures of Lycoming SR 15 pavement, Superpave over concrete, southbound......... 31

Figure 16 Transverse profile at Snyder SR 11- southbound passing lane. .................................. 33

Figure 17 Transverse profile at Snyder SR 11- southbound travel lane...................................... 33

Figure 18 Transverse profile at Snyder SR 11- southbound travel lane...................................... 34

Figure 19 Pictures of Snyder SR 11 pavement, southbound. ...................................................... 36

Figure 20 Transverse profile at Clearfield SR 153- northbound, PG 64-22 section. .................. 39

Figure 21 Transverse profile at Clearfield SR 153- northbound, PG 64-28 section. .................. 39

Figure 22 Pictures of Clearfield SR 153 pavement, PG 64-22 section........................................ 42

Figure 23 Pictures of Clearfield SR 153 pavement, PG 64-28 section........................................ 43

Figure 24 Transverse profile at Centre I-80, eastbound, MP 167.0 to MP 167.5........................ 46

Figure 25 Transverse profile at Centre I-80, eastbound, MP 167.5 to MP 168........................... 46


Figure 27 Transverse profile at Centre I-80, eastbound, MP 168.5 to MP 169........................... 47

viii


Figure 29 Pictures of Centre I-80 pavement. ............................................................................... 50

Figure 30 Pictures of Centre I-80 pavement. ............................................................................... 51

Figure 31 Transverse profile at Huntingdon SR 522, southbound. ............................................. 53

Figure 32 Pictures of Huntingdon SR 522 pavement. ................................................................. 54

Figure 33 Creep Compliance versus reduced time for ID-2 and Superpave Sections

at Lycoming SR 153. ............................................................................................................ 57

Figure 34 Creep compliance (1/MPa) vs. time(s) for CR 64-22. ............................................... 59

Figure 35 Creep compliance (1/MPa) vs. reduced time(s) for CR 64-22.................................... 59

Figure 36 Log shift factors vs. temp for CR 64-28...................................................................... 60

Figure 37 Creep compliance (1/MPa) vs. time(s) for CR 64-28. ................................................ 60

Figure 38 Creep compliance (1/MPa) vs. reduced time(s) for CR 64-28.................................... 61

Figure 39 Log shift factors vs. temp for CR 64-28...................................................................... 61

Figure 40 Comparison of master curves of both sites on log-log domain. .................................. 62

Figure 41 Comparison of shift factor curves for both sites. ........................................................ 63

Figure 42 Strength test results for CR 64-22. .............................................................................. 64

Figure 43 Strength test results for CR 64-28. .............................................................................. 64

Figure 44 Creep compliance vs. time – Huntingdon. .................................................................. 66

Figure 45 Creep compliance vs. reduced time – Huntingdon...................................................... 66

Figure 46 Log shift factor curve – Huntington. ........................................................................... 67

Figure 47 Indirect tensile strength test results– Huntington SR 522. .......................................... 68

Figure 48 Creep compliance vs. time for cores 10, 11, and 12 between MP 169 and

169.5 (I-80 Centre). .............................................................................................................. 70

Figure 49 Creep compliance vs. reduced time for cores between MP 169 and

169.5 (I-80 Centre). .............................................................................................................. 70

Figure 50 Log shift factor vs. temp for cores 10, 11, and 12....................................................... 71

Figure 51 Creep compliance vs. time for cores 6 and 7 between MP 168 and

168.5 (I-80 Centre). .............................................................................................................. 71

Figure 52 Creep compliance vs. reduced time for cores between MP 168 and 168.5................. 72

Figure 53 Log shift factor vs. temp for cores 6 and 7.................................................................. 73

Figure 54 Comparison of master curves for I-80......................................................................... 73

ix

Figure 55 Comparison of shift factors (I-80)............................................................................... 74

Figure 56 Strength values for cores between MP 169 and 169.5. ............................................... 75

Figure 57 Strength values for cores between MP 168 and 168.5. ............................................... 75

Figure 58 Measure rut depth at different sites. ............................................................................ 81

Figure 59 Rut Depth versus CHRST permanent shear strain of the wearing layer. .................... 83

Figure 60 Binder modulus for Clearfield SR 153-PG 64-28 from PAV simulation

and field cores. ...................................................................................................................... 85

Figure 61 Binder modulus for Clearfield SR 153-PAV simulation: PG 64-28 versus

PG 64-28. .............................................................................................................................. 85

Figure 62 Binder modulus for Clearfield SR 153 field cores: PG 64-28 versus PG 64-28........ 86

Figure 63 Binder modulus for Huntingdon SR 522 PAV simulation versus field cores............. 86

x

LIST OF TABLES

Table 1 Projects Selected for Condition Survey under Task 2. ..................................................... 6

Table 2 Projects Selected for Coring. ............................................................................................ 7

Table 3 Pavement Sections Surveyed or Cored Under WO-9....................................................... 8

Table 4 Tests Conducted on the Cores for WO-9 Project. .......................................................... 15

Table 5 Tests Conducted on the Asphalt Binder for WO-9 Project. ........................................... 15

Table 6 Measured Rut Depth for Lycoming SR 15 – Northbound.............................................. 27

Table 7 Measured Rut Depth for Lycoming SR 15 – Southbound.............................................. 28

Table 8 Measured Rut Depth for Snyder SR 11 – Southbound................................................... 34

Table 9 Measured Rut Depth for Snyder SR 11- Southbound. ................................................... 35

Table 10 Measured Rut Depth for Clearfield SR 153-Northbound............................................. 40

Table 11 Measured Rut Depth for Centre I-80, Eastbound. ........................................................ 48



Table 14 Measured Rut Depth for Huntingdon SR 522, Southbound. ........................................ 53

Table 15 Thicknesses and Specific Gravities for Cores Tested Under WO-9............................. 55

Table 16 Comparison of Design and Measured Gmm for the Wearing Course .......................... 56

Table 17 SR 153 Cores Selected for IDT. ................................................................................... 58

Table 18 Log Shift Factors for Both Sections at SR 153............................................................. 63

Table 19 Sigmoidal Coefficients for Both Sections at SR 153.................................................... 63

Table 20 Huntingdon SR 522 Cores Selected for IDT. ............................................................... 65

Table 21 Sigmoidal Coefficients – Huntington. .......................................................................... 67

Table 22 Shift Factors – Huntington............................................................................................ 67

Table 23 Strength Test – Huntington........................................................................................... 68

Table 24 Details of Cores Selected for IDT from Centre I-80. ................................................... 69

Table 25 Strength Values for All Cores in I-80........................................................................... 76

Table 26 Log Shift Factors for All Cores in I-80. ....................................................................... 76

Table 27 Sigmoidal Coefficients for All Cores in I-80. .............................................................. 76

Table 28 Results of Resilient Modulus Test for Centre I-80....................................................... 77

xi

Table 29 Results of Resilient Modulus Test for Huntingdon SR 522. ........................................ 77

Table 30 Results of PSPA Testing at Huntingdon SR 522.......................................................... 79

Table 31 Shear Test Results for Cored Projects and Correspondence with Measured

Field Rut Depth..................................................................................................................... 82

Table 32 Comparing Modulus of Binder from PAV Simulation with That of Field Cores. ....... 84

xii

ACKNOWLEDGEMENTS The work upon which this report is based is the result of two years of field and laboratory investigation. Financial support for this project was provided by the Pennsylvania Department of Transportation (PennDOT) and the Mid-Atlantic Universities Transportation Center (MAUTC). This support is greatly appreciated. Ms. Michelle Tarquino and Ms. Lisa Karavage of the PennDOT Bureau of Research and Planning served as project managers. Their guidance is truly appreciated. Mr. Tim Ramirez of the PennDOT Bureau of Construction and Materials served as technical liaison with PennDOT. His counsel and directions were great and highly needed. Also recognized is the invaluable help provided by Mr. Dean Maurer of the Bureau of Construction and Materials. Mr. Maurer was instrumental in helping the research team with all of the site visits and identifying the projects to be investigated. The authors are also grateful to Ms. Janice Dauber of Penn State, who served as the research coordinator and oversaw the MAUTC portion of the project. Mr. Michael Casper and Ms. Mara Poorman provided support with editing and formatting the report and their assistance is appreciated. Penn State graduate students Qinwu Xu and Laxmikanth Premkumar provided valuable assistance with the laboratory testing. Finally, great appreciation is extended to all PennDOT personnel who assisted the research team with field visits, traffic control, and coring the pavements of the visited sites.

This work was sponsored by the Pennsylvania Department of Transportation and the U.S. Department of Transportation, Federal Highway Administration. The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of either the Federal Highway Administration, U.S. Department of Transportation, or the Commonwealth of Pennsylvania at the time of publication. This report does not constitute a standard, specification, or regulation.

xiii

EXECUTIVE SUMMARY

At the beginning of the implementation of the Superpave system in the Commonwealth of

Pennsylvania, a series of projects were selected for detailed study to validate and determine the

effectiveness of this system in designing asphalt concrete mixtures. Consequently, a research project

titled “Superpave Validation Studies” was sponsored by Pennsylvania Department of Transportation

(PennDOT) in 1999. That study, known as Work Order 43, was conducted by the Northeast Center

of Excellence for Pavement Technology (NECEPT) at The Thomas D. Larson Pennsylvania

Transportation Institute (LTI). In a 2003 report, the data, findings, and conclusions from that study

were presented to PennDOT (Anderson et al., 2003). The WO 43 study was focused on the general

characteristics of materials used in Superpave design. That includes both binder and mixture

properties. Overall, the study included extensive laboratory testing of the materials obtained at the

time of construction to capture the engineering properties and to determine if the Superpave

mixtures exhibit adequate levels of resistance to rutting, thermal cracking, and fatigue damage.

Asphalt binder and asphalt concrete from more than 10 Superpave projects were obtained and tested

at NECEPT laboratories during WO 43. The WO 43 study did not include field performance

evaluation and in that respect the laboratory test results could not be correlated to the observed field

performance. As a result, PennDOT initiated a new work order (WO-9) titled “Field Focused

Superpave Validation” to complement findings of WO 43 through field performance measurements.

A number of WO 43 pavements were selected for evaluation. The projects were visited and detailed

data of observed distresses (rutting, cracking, and raveling) were collected. Some of the projects

were cored and the cores were tested at NECEPT laboratories. Major laboratory tests on cores

included specific gravity measurements, indirect tensile resilient modulus, indirect tensile creep and

strength, extraction and binder recovery, and finally, determination of the binder dynamic modulus

using the dynamic shear rheometer.

The pavement sections evaluated for this research were 9 to 10 years old at the time of the

pavement condition survey. They mostly exhibited satisfactory performance. The average rutting

was 5.4 mm and 6.4 mm for right wheel path and left wheel path, respectively, when all surveyed

projects are considered. The lowest measured rutting was about 2 mm (Centre I-80 right lane) and

the highest 11 mm (Lycoming SR 15, Southbound). The laboratory test results from the repeated

shear constant height tests on the wearing course at 52 ºC, conducted during the WO 43 project were

compared with the rut levels observed. No clear trend could be found. However, it could be

xiv

concluded that the laboratory shear strain values under 1 percent result in an acceptable rutting level

in the field.

The two pavement sections with the most dominant cracking were the ID-2 Marshall section

on the northbound lanes of Lycoming SR 15 and the PG 64-22 section of Clearfield SR 153.

Laboratory tests of indirect creep at low temperatures indicated lower compliance of these two

mixes compared to their companion sections at each site.

An investigation was also made into the level of aging observed in the field and how this

aging compares with laboratory-simulated aging. Such comparative analysis was conducted for

those projects from which cores were available. That includes Clearfield SR 153, Huntingdon SR

522, and Centre I-80. The results indicated that for both PG 64-28 and PG 64-22 sections at

Clearfield SR 153, the PAV laboratory simulation provided a significantly higher aging level (stiffer

binder) compared with actual aging observed in the field for a 10-year-old pavement. For the

Huntingdon SR 522 with an original PG 64-28 binder, the field-aged binder is closer to the PAV-

aged binder for this 9-year-old pavement. However, the wheel path core indicated lower stiffness

than the PAV laboratory simulation while the between-wheel-path core indicted higher aging.

Significantly higher air void level of between-wheel-path core could have contributed to the higher

level of aging observed for the binder of this core.

The overall conclusion from this study was that most of the projects included in the detailed

survey demonstrated satisfactory performance considering their age. Rutting levels were acceptable

and there were no considerable levels of cracking except the two cases mentioned above. Surveys of

these pavements indicated that longitudinal joint construction continues to be a serious concern, as

several projects were found with longitudinal joint cracks extending over a significant stretch of the

pavement.

Laboratory rutting tests (constant height repeated shear test at high temperature) on wearing

course did not deliver a good correlation with rutting levels observed, but the data provide a guide as

to the range of laboratory strain levels that could result in acceptable rutting levels. Unfortunately,

sufficient laboratory shear strain data were not available for the binder course of all pavements

surveyed, and it did not become possible to investigate the relationship between the rutting level and

the laboratory test results on the pavement binder layer.

1

CHAPTER ONE INTRODUCTION

The Superpave design system came into existence in the mid-1990s. Many pavements have

been constructed with Superpave designed hot mix asphalt (HMA). Today, this technology is well

established in many states. It has been over a decade since the Commonwealth of Pennsylvania

began using this system for designing HMA.

Since its inception, the system has gone through several specification revisions. The

compaction effort in the Superpave Gyratory Compactor was revised at the early stages, and a

simplified compaction requirement was introduced (Brown and Buchanan, 1999). The restriction on

aggregate grading, referred to as the restricted zone, was eliminated (Kandhal and Cooley, 2001).

There has been general satisfaction with the pavements constructed with this mix, and anecdotal

evidence suggests that Superpave pavements are performing well in Pennsylvania; however, within

the last several years there has been concern raised in regard to the durability of some Superpave

mixes. Some have reported these problems as a result of insufficient binder content in the mix. This

issue has been the driving force for several states to take measures to increase the binder content in

the mix. Some have been designing at a reduced number of gyrations while others have been

designing at an air void level about 1/2 percent lower than what is specified in Table 6 of AASHTO

specification M323-04. Both of these changes result in higher design binder content. There has also

been a move by some to increase the minimum required VMA to allow more space within the

aggregate structure for asphalt and therefore provide a higher binder content mix at a specified

design air void level. The Pennsylvania Department of Transportation (PennDOT) is now

specifying 1/2 percent higher VMA for all aggregate-size gradations than is specified in AASHTO

M323.

As the Superpave design criteria are evolving, it is worth looking back into the performance

of the pavements constructed with Superpave mixes. The research findings presented in this report

are the result of such effort, i.e., evaluating long-term performance of Superpave-designed mixes.

BACKGROUND

At the beginning of the implementation of Superpave in the Commonwealth, a series of

projects was selected for detailed study to validate and to determine the effectiveness of the

Superpave system in designing asphalt concrete mixtures of superior durability. Consequently, a

2

research project titled “Superpave Validation Studies” was sponsored by the Pennsylvania

Department of Transportation (PennDOT) in 1999. That study, under the University-Based

Cooperative Agreement (Contract No. 359704) Work Order 43, was conducted by the Northeast

Center of Excellence for Pavement Technology (NECEPT) at the Thomas D. Larson Pennsylvania

Transportation Institute (LTI). The data, findings, and conclusions from that study were presented to

PennDOT (Anderson et al., 2003). The WO-43 study focused on the general characteristics of

materials used in Superpave design, which includes both binder and mixture properties. Overall, the

study included extensive laboratory testing of these materials to capture the engineering properties

and to determine whether the Superpave mixtures exhibit adequate levels of resistance to rutting,

thermal cracking, and fatigue damage. Asphalt binder and asphalt concrete from more than 10

Superpave projects were obtained and tested at NECEPT laboratories during the WO-43. The goal

of the WO-43 study was also to determine whether the Superpave mixture performance-related tests

could be used to reliably predict mixture performance in the field. While laboratory testing was

comprehensive in the WO-43 project, it did not include field performance evaluation, and in that

respect, the laboratory test results could not be correlated to the observed field performance. No field

survey was conducted on these projects during the WO-43, and, therefore, no analysis was

conducted in regard to the relationship between the predicted performance from laboratory

characterization and the actual performance of these projects in the field. It was considered essential

for many of the WO-43 projects to be monitored and surveyed after several years in service and for

accurate measurements of rut depth, fatigue cracking, and thermal cracking to be made for these

projects. As a result, PennDOT initiated a new work order (WO-9) titled “Field Focused Superpave

Validation” to complement findings of WO-43 through field performance measurements. This work

was undertaken to evaluate the performance of these projects after they have been in service for

several years and determine their relationship with the material properties established in the

laboratories.

OBJECTIVES

The objectives of the WO-9 project could be summarized as follows:

• Follow up on the actual field performance of all the projects analyzed in the WO-43 project where materials were collected and materials characterization testing was performed.

• Conduct a pavement distress survey and performance measurements (rutting, cracking, etc.) of selected project pavement sections.

3

• Conduct laboratory material characterization testing on material from pavement cores drilled from some of the projects.

• Analyze and compare field-collected performance measurements and laboratory materials characterization results to the predicted performance from the original laboratory material characterization testing.

RESEARCH APPROACH AND SCOPE OF WORK

Through coordination with the PennDOT technical manager for this research project, a

number of WO-43 pavements were selected for evaluation. Selection was based on a number of

factors: availability of laboratory data and worthiness of the project in terms of comparative analysis

among different sections built for the pavement under the same project. In two cases, in spite of

insufficient laboratory data, the decision was made to conduct the pavement evaluation because of

the significance of the project in terms of comparing different designs or binders. The projects were

visited, and detailed data of observed distresses were collected. Some of the projects were cored,

and the cores were tested at NECEPT laboratories. Information from the pavement condition survey

and laboratory testing were analyzed. Findings are provided in this report.

4

CHAPTER TWO Scope of Field and Laboratory Investigation

Two major goals of this project were to evaluate and assess the condition of selected

pavements constructed during WO-43 research project, and to conduct an investigation into the

relationship between laboratory results and field observations. This chapter provides details of how

these two tasks were completed.

PAVEMENT CONDITION SURVEY

The first step toward establishing a framework for conducting field survey of projects

considered under WO-43 was to determine the extent of available laboratory data and sampled

materials. Task 1 of this research was directed toward this goal and was the basis for selection of

projects studied under WO-9.

Status of Available Data for Projects Considered Under WO-43

Nineteen projects were identified as the projects considered under WO-43. These projects

had been selected to evaluate the impact of a range of project variables on pavement performance.

Examples of such variables include differences in performance grade (PG) binders, differences in

performance of polymer modified binders, Superpave versus ID-2 Marshall mixes, layer thickness,

slow-moving vehicles, and pavement grade. Not all of these projects were selected for

comprehensive evaluation and material characterization under WO-43. The extent of material

procurement was vastly different for these projects. For some, a considerable amount of binder and

mixture had been collected. For others, no material was procured at the time of construction. The

extent of the laboratory work on the procured materials also varied within a wide range. Data from a

relatively comprehensive set of tests on both the binders and mixtures are available for some

projects. For others, testing has been very limited, and little laboratory data are available.

Table A.1 (Appendix A) presents the list of projects under WO-43. It is clear from this table

that the level of available data from laboratory material characterization varies within a wide range.

For four of the projects (Warren 0062, Schuylkill 0081, Bucks 0131, and Indiana 0022), no data are

available. The original plan called for the data from Schuylkill 0081 to come from a different

source; therefore, no material was received at NECEPT laboratories for this project. There was no

material received for Bucks 0131 and Indiana 0022 either. Of the four projects with no data, Warren

0062 is the only project for which materials of asphalt mixture for wearing and binder mixtures have

5

been received at NECEPT laboratories and are still available. Records also indicate that Warren

materials are available at PennDOT Materials and Test Division laboratories. For the Berks 0061

project, limited laboratory work has been conducted, and only volumetric and repeated shear test

data for the PG 64-22 mixture of this project are available.

For three of the projects (Crawford 0322, Centre 0080, and Huntingdon 522), only some

binder data are available. The Clearfield 0080 project is an important one considering the use of a

control binder along with five modified binders (with Novophalt, Polybilt, Kraton, Styrelf, and

Gilsonite). However, this project was milled and overlaid several years ago.

The Centre I-80 project is of interest because of using different aggregate size gradations for

wearing and binder courses and using different layer thicknesses. Unfortunately no mixture or

binder data is available for the Centre 0080 project, and there is currently no material of this mixture

available at NECEPT laboratories.

There is no mixture data currently available for the Huntingdon 522 project; however, binder

and base mixtures form this project are available at NECEPT laboratories in case of a future need to

conduct characterization tests on the mixtures. For the remaining projects, both the binder and

mixture data are available to various degrees. The most comprehensive laboratory data exists for

Lycoming 0015, York 0083, Franklin 0011, and Indiana 0422, and these were the projects originally

considered with the best chances of evaluation based on the laboratory data. Franklin 0011 is also of

interest because of using various polymer-modified binders.

Inventory of Materials

An investigation was conducted to determine the amount of binder and mixtures of WO-43

projects available at NECEPT laboratories. This was done to assess the possibility of conducting

further laboratory material characterization tests in case of a future need under an extension project.

Tables A.2 (Appendix A) presents the binder materials from WO-43 projects that are currently

available at NECEPT laboratories. The table indicates that the binder is available for several

projects; however, the available material is mostly for the projects for which binder characterization

data are already available. No material could be found for projects that have not been already

included for binder testing. Currently available binders could be used to complete the direct tension

test for those projects for which this property has not been already determined.

The available mixtures from different projects are presented in Table A.3 (Appendix A).

Available mixture from the Snyder 0011 project could possibly be used in limited testing, in case

6

needed under an extension project, to complete the current data set and to provide data from indirect

tensile test (IDT) for evaluation of low temperature cracking. In addition, the repeated shear test

data are not available for the binder course of this project, but the material is available to conduct a

limited number of such tests. For Fayette 0119, there is sufficient material to conduct one or more of

the mixture tests (strain controlled frequency sweep, the repeated shear test, and IDT) for the base as

well as the IDT for the binder course, for which there are no data available at this point. Similarly,

as shown in Table A.3, there is limited mixture available for York 0030. While there is currently

binder data available for this project, no mixture data could be found. Therefore, the available

mixture material for York 0030 could be tested to provide characterization of the mixture for this

project.

A list of cores currently available at NECEPT laboratories, as obtained as part of WO-43

project, is provided in Table A.4. The largest number of available cores belongs to binder layers of

Lycoming SR 15 and York SR 30. The existing inventory of materials (binders and mixtures) at

NECEPT could be integrated with the existing inventory at the laboratories of PennDOT Materials

and Tests Division.

Projects Selected for Performance Evaluation

Task 2 of WO-9 was dedicated to surveying the condition of pavements considered under

WO-43. The results of Task 1 analysis and consultation with the PennDOT technical manager were

used in deciding which of the WO-43 projects should be included in the pavement condition survey.

The projects presented in Table 1 were selected for evaluation under Task 2.

Table 1 Projects Selected for Condition Survey under Task 2.

District S.R.-Sec. - County 2-0 0153 - 225 - Clearfield 2-0 0080 - B22 - Centre 3-0 0015 - B43 - Lycoming 3-0 0015 - B42 - Lycoming 3-0 0011 - 38M - Snyder 8-0 0083 - 832 - York 8-0 0030 – B01 - York 8-0 0011-024 - Franklin 9-0 0070 - 009 - Fulton 9-0 522 - 001- Huntingdon 10-0 0422 - 404 - Indiana

7

Out of the projects presented in Table 1, six were selected for further evaluation and more

detailed analysis through procurement of cores (Table 2). This selection was considered to include

those projects with the largest available mixture and binder data or at least those for which a

comparative study of different sections would be valuable.

Table 2 Projects Selected for Coring.

District S.R.-Sec. - County

2-0 0080 - B22 - Centre

2-0 0153 - 225 - Clearfield

3-0 0011 - 38M - Snyder

3-0 0015 - B43 - Lycoming

3-0 0015 - B42 - Lycoming

9-0 522 - 001- Huntingdon

Scope of Performance Evaluation

Evaluation of pavements was conducted at two stages. The first stage, considered

preliminary evaluation, was carried out to

• identify location of the sections for detailed evaluation. • provide initial assessment of pavement condition. • determine whether the pavement is a good candidate for detailed evaluation.

The PennDOT and PTI personnel were both present at the site for the preliminary evaluation.

Based on this evaluation, I-70 in District 9 and SR 422 in District 10 were dropped from the list for

detailed evaluation. The former was found to be too extensive in terms of number of sections to be

included in this research and appeared to be a good candidate for thorough investigation under a

different research project. The latter was dropped since the pavement was found to have been

overlaid. The decision was made to continue with a detailed condition survey of the remaining nine

projects presented in Table 1. As the detailed investigation of projects began, difficulties arose with

scheduling site visits for some of the sites within the time frame of the project, and finally, the

detailed evaluation could only be conducted for six of the nine selected projects. Similarly, coring

was only conducted for three of the six projects selected even though all six were marked for coring

at the time of the detailed evaluation. Table 3 summarizes what was finally accomplished regarding

8

the pavement condition evaluation and coring for selected projects. The date of completing the

activity is also provided in the table.

Table 3 Pavement Sections Surveyed or Cored Under WO-9.

District S.R.-Sec. - County

Preliminary

Evaluation

Detailed

Evaluation

Coring

2-0 0153 - 225 - Clearfield

11/14/06

07/11/07

07/18/07

07/11/07

07/18/07

2-0 0080 - B22 - Centre 11/14/06 07/19/07

07/31/07

07/31/07

3-0 0015 - B43 - Lycoming 11/13/06 06/05/07 __

3-0 0015 - B42 - Lycoming 11/13/06 06/06/07 __

3-0 0011 - 38M - Snyder 11/13/06 06/14/07 __

8-0 0083 - 832 - York 04/09/07 __ __

8-0 0030 – B01 - York 04/09/07 __ __

8-0 0011-024 - Franklin 12/05/06 __ __

9-0 0070 - 009 - Fulton 12/05/06 __ __

9-0 522 - 001- Huntingdon 12/05/06 11/08/2007 11/08/2007

01/08/08

10-0 0422 - 404 - Indiana 11/14/06 __ __

Detailed Pavement Evaluation Procedure

Conducting a detailed pavement performance evaluation was a major part of this project.

The main idea was to determine the quality of these Superpave pavements after being in service for

9 to 10 years. The surveyed pavements were built between 1997 and 1998. The total length of the

pavement section surveyed varied for each project depending on the project size, number of sections,

geometric limitations, and time limitations. Overall, the total length of each surveyed section was

between 750 and 1500 feet. The total length surveyed for each project was dependent on the number

of sections surveyed and for the longest one was 5,000 feet. The travel lane (right-hand lane in

direction of traffic) was selected as the survey lane. Clearfield SR 153 and Huntingdon SR 522,

9

were both two lane roads, and therefore, for the former, the northbound lane was surveyed, and for

the latter, the southbound was considered. Another exception was the Snyder SR 11 project, for

which both the passing and travel lanes on the southbound side were surveyed.

At each site location, once traffic control was established, the start and end points of the

survey area were established. The pavement shoulder was then marked at 100-ft intervals to provide

the opportunity for detailed mapping of distresses at small intervals. This was followed by taking

numerous photos of the pavement mat throughout the whole stretch of the road selected for survey.

A transverse profiler was used to determine the rut depth. Transverse profiling of the pavement and

determination of crack length and type were conducted in parallel. A wheel manufactured by

Calculated Industries (DigiRoller Plus 2) was used to measure the crack length. FHWA publication

“Distress Identification Manual for the Long-Term Pavement Performance Program” was used as a

guide for determination of crack type and severity.

Transverse Profiles (Rutting)

Transverse profiles at each site were captured at 200- to 400-ft intervals. At least five

profiles were captured for each project, and three profiles were obtained for each section if the

project contained more than one section.

The rut depth measurement equipment was a simple system consisting of a 14-ft long

aluminum I-beam, a depth gauge, and a laptop computer to capture data (Figure 1). The beam

spanned the pavement section transversely, resting on tripods at both ends. A Mitutyo Digimatic

Absolute Depth Gauge was aligned vertically adjacent to the beam and connected to a laptop

computer. Every time the triggering button on the meter was activated, the measured depth was

transferred to the spreadsheet file developed on the laptop computer. Measurements with this

system were conducted at 50 mm intervals along the beam.

10

Figure 1 Transverse profiling using the digital depth meter.

Criterion to Determine Rut Depth

Rutting manifested at the pavement surface is the result of densification of HMA layers and

shoving of the material to the sides due to shear load imposed by load on the wheel path. It is also

partly the result of densification and shear movement of the underlying unbound layers.

The approach presented in Figure 2 was uniformly followed for all projects to determine rut

depth. A straight line was applied tangent to the two peaks observed at the shoulder and at the line

between two lanes. The distance between the mid-point of this tangent and the deepest point in the

wheel path was measured and considered as the rut depth.

11

Typical Transverse Profile

98

100

102

104

106

108

110

04080120160200240280320360400440Distance, cm

Rea

ding

, mm

Rut

h D

epth

Figure 2 Approach used in this project to determine rut depth.

Field Seismic Modulus Testing

Parallel to obtaining cores, attempts were made to determine in-situ elastic modulus of

asphalt concrete using Portable Seismic Pavement Analyzer (PSPA).

Theoretical Background

If an elastic half-space is disturbed by a vertical impact on the surface, two types of waves

will propagate in the medium: body and surface waves. Body waves propagate radially outward in

the medium and are composed of two different types: compression and shear waves. These waves

are differentiated by the direction of particle motion relative to the direction of wave propagation.

Particle motions associated with shear waves are perpendicular to the direction of wave propagation,

whereas particle motions associated with compression waves are parallel to the direction of wave

propagation. Surface waves resulting from a vertical impact are primarily Rayleigh waves, which

propagate away from impact along a cylindrical wavefront near the surface of the medium.

The Spectral Analysis of Surface Wave (SASW) method can be used for in situ evaluation of

elastic moduli and layer thicknesses of layered systems like soils and pavements (Nazarian and

Stokoe 1984). The method is based on the phenomenon of Rayleigh wave dispersion in layered

12

systems, i.e. the phenomenon that the velocity of propagation is frequency dependent. Because shear

wave velocity and shear modulus are mainly dependent on the effective stress and density, the

SASW method is useful in estimating the changes in material strength and density. In layered media,

the velocity propagation of surface waves depends on the frequency (or wavelength) of the wave

because waves of different wavelengths sample different parts of the layered medium. The algorithm

of the SASW method is to determine the velocity-frequency relationship described by the dispersion

curve, and then, through the process of inversion or backcalculation, to obtain the shear wave

velocity profile. Elastic moduli profiles can then be easily obtained using simple relationships with

the velocity of propagation and measured or approximated values for mass density and Poisson’s

ratio in two steps:

1. The relationship amongst velocity, V, travel time, Δt, and receiver spacing, ΔX, can be written in the following form:

tXV

ΔΔ

= (1)

In this equation, V can be the propagation velocity of any of the three waves (i.e.

compression wave, VP; shear wave, VS; or surface (Rayleigh) wave, VR). Knowing wave

velocity, the modulus can be determined in several ways.

2. Elastic modulus, E, can be determined from shear modulus, G, through the Poisson's ratio, υ, using:

GE )1(2 υ+= (2)

Shear modulus can be determined from shear wave velocity, VS, and mass density, ρ,

using:

2

SVG ρ= (3)

Portable Seismic Pavement Analyzer

The Portable Seismic Pavement Analyzer (PSPA), as shown in Figure 3, is a device designed

to determine the modulus of the top pavement layer in real-time. The PSPA consists of two receivers

13

(accelerometers) and source packaged into a hand-portable system which can perform high

frequency seismic tests.

source

electronics box

receivers

source

electronics box

receivers

Figure 3 Portable Seismic Pavement Analyzer (PSPA)

The analysis method implemented in the PSPA is called the ultrasonic surface waves (USW)

method which is a simplified version of the SASW method. The major distinction between these two

methods is that, in the USW method, the modulus of the top pavement layer can be directly

determined without an inversion algorithm (Nazarian et al. 1993). As surface waves (Rayleigh, R

waves) contain most of the seismic energy, the USW method utilizes the surface wave energy to

determine the variation in modulus with wavelength. Detailed review of NDT applications using

surface wave methods can be found elsewhere (Nazarian et al. 1993, Goel and Das 2006). At

wavelengths less than or equal to the thickness of the uppermost layer, the velocity of propagation is

independent of wavelength. Therefore, if one simply generates high-frequency (short-wavelength)

waves, and if one assumes that the properties of the uppermost layer are uniform, the shear wave

velocity of the upper layer, VS, can be calculated from surface wave velocity, VR:

)16.013.1( υ−= RS VV (4)

Then, the elastic modulus of the top layer, E, can be determined:

14

[ ]2)16.013.1()1(2 sVE υυρ −+= (5)

Field PSPA Testing

To collect data with a PSPA, the technician initiates the testing sequence through the

computer. The high-frequency source is activated four to six times. The outputs of the two receivers

from the last three impacts are saved and averaged (stacked). The other (pre-recording) impacts are

used to adjust the gains of the amplifiers. The gains are set in a manner that optimizes the dynamic

range. Typical voltage outputs of the three accelerometers are shown in Figures 4a. In this plot, the

red line presents the signal from the electronic source, while black and green lines indicate signals

from accelerometers 1 and 2. An actual variation in modulus with wavelength from the time records

(data reduction process) is shown in Figures 4b. For practical reasons, the wavelength is simply

relabelled as depth. In that manner, the operator of the PSPA can get a qualitative feel for the

variation in modulus with depth. The red solid line represents the average seismic modulus of the

pavement layers. It should be noted that the modulus at a depth smaller than 50 mm could not be

determined due to the fixed spacing between the two accelerometers of the PSPA. The dispersion

curve shown in Figures 4b is developed from the phase spectra shown at the bottom of the same

figure. The phase spectrum, which can be considered as an intermediate step between the time

records and the dispersion curve (Nazarian et al. 1993), is determined by conducting Fourier

transform and spectral analysis on the time records from the two accelerometers. This step makes the

determination of the modulus with wavelength much easier.

(a) signal (b) data reduction

Figure 4 Sample PSPA data

15

LABORATORY INVESTIGATION

The laboratory investigation included preparation of the cores and conducting a series of

tests on the prepared cores. Preparation included taking pictures of the cores, assessment of the core

condition, measuring thickness of the different layers on each core, and cutting cores to separate

different layers. Testing included indirect tensile resilient modulus, indirect tensile creep and

strength, specific gravities, extraction, determination of gradation and asphalt content, binder

recovery, and determination of binder stiffness using a dynamic shear rheometer. Tables 4 and 5

present the tests conducted on the cores and the asphalt binder, respectively:

Table 4 Tests Conducted on the Cores for WO-9 Project.

Designation Standard Method of Test for AASHTO

T 322-03

Determining the Creep Compliance and Strength of Hot-Mix Asphalt

(HMA) Using the Indirect Tensile Test Device

ASTM D4123 Standard Test Method for Indirect Tension Test for Resilient Modulus of

Bituminous Mixtures

AASHTO

T 166-05

Bulk Specific Gravity of Compacted Hot-Mix Asphalt Using Saturated

Surface-Dry Specimens

AASHTO

T 209-05

Theoretical Maximum Specific Gravity and Density of Hot-Mix Asphalt

Paving Mixtures

AASHTO

T 164-05

Quantitative Extraction of Asphalt Binder from Hot-Mix Asphalt (HMA

AASHTO

T 30-05

Mechanical Analysis of Extracted Aggregates

Table 5 Tests Conducted on the Asphalt Binder for WO-9 Project.

Designation Standard Method of Test for ASTM

D5404-03

Recovery of Asphalt from Solution Using the Rotary Evaporator

AASHTO

T 315-05

Determining the Rheological Properties of Asphalt Binder Using A

Dynamic Shear Rheometer (DSR)

The bulk specific gravity of the cores was determined using AASHTO T166. This was

followed by the indirect tensile testing. Afterward, the cores were broken loose in an oven set at a

temperature of 135°C for a period of 30 to 60 minutes depending on the size of the specimen. This

16

was followed by determination of the maximum theoretical specific gravity (Gmm) of the cores

according to AASHTO T209. Upon completion of the Gmm tests, the cores were processed through

extraction (AASHTO T164) so that the binder could be recovered (ASTM 5404). The recovered

binder from these cores was subject to determination of the complex modulus using the dynamic

shear rheometer (AASHTO T315).

Preparation of Cores

Cores were first photographed, and the thickness of different layers for each core was

measured. The pictures of the cores are provided in Appendix B. The cores were then cut at the

layer interface using a single saw blade to provide separate specimens from each core representing

different pavement layers.

Indirect Tensile Creep and Strength Testing

Testing apparatus:

All IDT tests were carried out using hydraulic loading systems manufactured by MTS®. The

MTS system consists of a 100 kN (22 kip) load frame and actuator interfaced with an MTS® 458.20

Micro Console fitted with an MTS® 458.91 MicroProfiler to program loading modes. An MTS®

409.80 temperature controller is interfaced with an environmental chamber that contains an electric

heater and a mechanism for handling liquid nitrogen for cooling. This temperature controller is

supplemented by a separate mechanism to monitor specimen temperature before testing. This is

accomplished by monitoring the temperature readout measured from a thermocouple embedded in a

dummy specimen that is prepared with the same mixture and satisfies all specifications for the actual

test specimen. Data acquisition is performed using a separate computer fitted with a National

Instruments® 6329 DAQ card. For tests in IDT mode, four XS-B LVDTs with a range of ±0.25 mm

are used to measure the vertical and horizontal deformation. These LVDTs are fitted onto aluminum

mounts sitting on steel targets. The targets are glued on the specimen using a five-minute epoxy.

Testing Protocol:

The testing protocol is in accordance with AASHTO T322. In this test, tensile creep and

tensile strength are determined on the same specimen for thermal cracking analysis. The tensile

creep is determined by applying a static load of fixed magnitude along the diametric axis of a

specimen for 100 seconds at temperatures of 0°C, -10°C, and -20°C (Figure 5). The horizontal and

17

vertical deformations measured across a gauge length of 1.5 inches near the center of the specimen

are used to calculate creep compliance as a function of time. Loads are selected to keep horizontal

strains in the linear viscoelastic range (typically below a horizontal strain of 500 µstrains) during the

creep test. After the fixed load is applied, the tensile strength will be determined by applying a load

to the specimen at the rate of 12.5 mm per minute (vertical ram movement) to failure at -10°C.

Typically, the maximum strength of the specimen occurs at a point prior to failure, and, hence, the

vertical and horizontal LVDTs measurements are used to accurately determine the value of tensile

strength (AASHTO T322). It was found earlier (NCHRP 530), as well as during the course of this

testing, that there could be possible damage to the LVDTs when the specimen fails during the

strength test. Hence, the LVDTs were removed prior to the strength test, and the correct strength was

determined using a correction equation developed by Christensen and Bonaquist (2004).

σIDT/Corr = 0.27 + 0.78*σIDT

Figure 5 Compression testing of the cores in diametral direction to determine indirect tensile

creep and strength.

Resilient Modulus Testing

Prior to conducting the indirect tensile creep tests on cores, indirect tensile resilient modulus

tests were conducted on cores from Huntingdon SR 522 and Centre I-80. The purpose of this

testing was to provide further information on the engineering properties of these two projects since

no original IDT data were available.

The resilient modulus tests were conducted in accordance with ASTM D4123. The values of

resilient modulus can be used to evaluate the relative quality of materials and also as an input for

18

pavement design or pavement evaluation and analysis. Being non-destructive in nature, multiple

tests can be repeated on the same specimen. Furthermore, this test can be used to study the effects of

temperature, loading rates, rest periods, etc. (ASTM D4123). Though different temperatures and

loading rates can be used for the test, in this study, all the tests were conducted at 25˚C with a

loading time of 0.1 seconds and rest period of 0.9 seconds because of time constraints. The number

of load cycles was restricted to maintain the cumulative vertical deformation within 0.0381 mm (100

μstrains). Though this limit was exceeded in some of the tests, they were well within the limits

defined by ASTM standards. The total resilient modulus was calculated in accordance with the

ASTM standards using the last five deformation cycles. A poison’s ratio value of 0.35 was assumed

for the calculation (Barksdale et al., 1997). A sample of the loading cycle, horizontal deformation,

and vertical deformation, as a function of time, are shown in Figures 6 through 8, respectively.

19

Load cycles (kN) vs Time(s)

-0.4

-0.35

-0.3

-0.25

-0.2

-0.15

-0.1

-0.05

71.5 72 72.5 73 73.5 74 74.5 75 75.5

Time(s)

Load

(kN

)

Figure 6 Load cycle (kN) vs. time(s).

Horizontal Deformation (mm) vs Time(s)

-0.0065

-0.0064

-0.0063

-0.0062

-0.0061

-0.006

-0.0059

-0.0058

-0.0057

-0.005670 70.5 71 71.5 72 72.5 73 73.5 74 74.5 75

Time(s)

Hor

izon

tal d

efor

mat

ion

Figure 7 Horizontal deformation (mm) vs. time(s).

20

Vertical Deformation(mm) vs Time(s)

0.008

0.0082

0.0084

0.0086

0.0088

0.009

0.0092

0.0094

0.0096

0.0098

0.01

55 55.5 56 56.5 57 57.5 58 58.5 59 59.5 60

Time(s)

Vert

ical

Def

orm

atio

n(m

m)

Figure 8 Vertical deformation (mm) vs. time(s).

The total resilient modulus is calculated using the formula:

ERI = P (VRT +0.27)/ (tΔHT)

where

ERI = Total resilient modulus of elasticity in MPa

P = Repeated load (kN)

VRT = Total resilient poisons ratio ( assumed as 0.35)

t = Thickness of specimen (mm)

ΔHT = Total recoverable horizontal deformation

Asphalt-Aggregate Extraction

After completion of mechanical testing, the binder from the cores was first extracted using

centrifuge extraction according to AASHTO T 164. Briefly, the extraction uses a centrifuge and

solvent to dissolve and extract the asphalt from a sample. The procedure requires a centrifuge,

solvent, container for catching the solvent, filter ring, and other standard laboratory equipment to

21

perform the test method. To begin, the test sample, filter, and empty ignition dish are weighed, and

the values are recorded. Next, the test sample is placed into the centrifuge bowl and covered with

the solvent. Enough time is allowed for the sample to get dissolved. After the sample has been

dissolved, the filter is placed on the bowl and covered with the lid tightly. A container is placed to

catch the solvent beneath the drain of the centrifuge. The centrifuge is started slowly, and the speed

is gradually increased to the maximum of 3600 rpm until the solvent ceases to flow from the drain.

After the centrifuge has stopped rotating, an additional 200 mL of solvent is added, and the

extraction continues. Additional solvent must be added in 200 mL quantities until the extract is

clear and no darker than a light straw color.

When the extract color flows clear from the drain, the filter ring is removed from the bowl

and is let to air dry. After air drying, the mineral matter is removed from the filter ring as much as

possible and is placed into the centrifuge bowl with the aggregate. Then, the filter ring is placed into

an oven at 163oC and dried to a constant mass, after which its weight is recorded. Next, the collected

extract solvent is agitated, and a 100-mL aliquot is measured and placed into the ignition dish. First,

the ignition dish is dried on a hot plate; then, it is burned at a dull, red heat at 600oC, cooled, and

weighed, and then 5 mL of saturated ammonium carbonate solution is added per gram of the ash.

The mixture is then digested at room temperature for one hour and then placed into an oven at 110oC

to dry and then cooled in a desiccator and weighed to 0.001 grams. Last, the volume of the extracted

solvent solution and also the mass of the extracted mineral matter are recorded.

Binder Recovery

Once extraction was completed, the binder was recovered using a rotary evaporator

according to ASTM D 5404. In brief, the binder is recovered from the solvent solution by using a

rotary evaporator to evaporate, condense, and then recover the solvent in a separate flask. The

binder remains in the distillation flask. First, an oil bath is heated to 140oC, and water is circulated

through the condenser. A 500-mL sample of the solvent solution is added to the distillation flask

and then is attached to the evaporator. Next, a vacuum is applied at 5.3 kPa, and a nitrogen flow of

500 mL/min is added to the system. The distillation flask is then lowered into the hot oil bath and

begins to rotate until most of the solvent solution is evaporated, and then an additional 500-mL

sample of the solvent solution is added, and this procedure is repeated until all of the solvent

solution has evaporated. After the bulk of the solvent has been distilled from the asphalt and no

noticeable condensation is occurring in the condenser, the flask is then immersed to a depth of 1.5

22

in, a vacuum is applied at an increased pressure of 80.0 kPa, and the nitrogen flow is increased to

600 mL/min. This is applied for a total of 15 minutes, after which the asphalt is then poured into

containers for storage.

23

CHAPTER THREE ANALYSIS, INTERPRETATION, AND FINDINGS

This chapter covers the results of field and laboratory investigation as part of this research

project. The chapter is divided into two major sections. The first section provides a discussion of

pavement evaluation, and the second section covers laboratory tests results and comparison of field

and laboratory data.

SECTION 1: RESULTS OF PAVEMENT CONDITION EVALUATION

The projects selected and visited under this research project and the approach taken in

evaluating pavement condition was presented in a preceding chapter. Details of each pavement

section and the range of distress evaluation are covered in Appendix C. In this section, for each

project, explanation is provided on the distresses observed and the overall condition of the

pavement.

Evaluation Results for SR 15 Northbound, Lycoming County

Cracking

ID-2 Section-Northbound: Cracking appeared dominant in this section. The width of the

cracks were mostly in the range of 1 to 5 mm, with a few as wide as 15 mm. Longitudinal cracks

were not significant, and the total length of this type of crack did not exceed 50 ft for the whole

stretch of road surveyed, and this was mostly both in the left and right wheel path. Transverse cracks

were more dominant as the total measured length was approximately 100 ft. No pattern could be

found for this cracking and was mostly sporadic. Remaining cracks on the pavement were mostly

fatigue cracking of low to medium severity and in a few spots were of high severity. The total area

of fatigued pavement was approximately 200 ft2. Longitudinal construction joint cracks between the

two lanes were severe and continuous for a long stretch of the surveyed section. There was also

significant longitudinal crack length observed to the right of the white stripe between the travel lane

and shoulder heading north.

Superpave Section-Northbound: The section overall looked good. Compared to the ID-2

section, very few cracked areas were observed at this section. Total length of all cracks was

approximately 95 ft. These cracks were mostly superficial and sporadic with no specific pattern.

24

There was a continuous stretch of 400 ft of cracking observed in longitudinal direction between the

wheel path for the first 400 ft of the section surveyed. In this cracked area, there were small areas of

minor raveling and segregation. No transverse cracks could be found on this section. After this 400-

ft stretch, the mat appeared in a significantly better condition, with no signs of raveled or segregated

areas. Contrary to the ID-2 section, the longitudinal construction joint cracking was also absent

from this section.

Superpave Section-Southbound: This is a Superpave section over jointed concrete

pavement. Fatigue and transverse cracks were absent from this section. Longitudinal cracking

appeared to be the only type of cracking observed in this section. The total length of this type of

crack was 470 ft in the 750-ft stretch of road that was surveyed. This length includes the

longitudinal crack observed between the travel and passing lanes. The length between wheel path

cracking (close to the center of the lane) was about 70 ft. The longitudinal cracking under the left

wheel path was approximately 230 ft, while the right wheel path cracking was about 54 ft. No

construction joint was observed for this section, implying possible construction of both lanes

together.

Rutting

Rutting for different sections is presented in Figures 9 through 12, and Tables 6 and 7. The

ID-2 section exhibits lower rutting, on the average, compared with the full-depth construction of the

northbound full-depth Superpave section and the southbound overlay Superpave section. This is

consistent with laboratory shear strain results for the wearing course as the ID-2 section had the

lowest permanent shear strain for the wearing layer as well as for the average of the strain for both

the wearing and binder layers, compared with the Superpave sections.

25

Figure 9 Transverse profile at Lycoming SR 15- northbound, ID2 section.

26

Figure 10 Transverse profile at Lycoming SR 15- northbound, Superpave section.

Figure 11 Transverse profile at Lycoming SR 15- southbound, Superpave overlay section.

27

Figure 12 Transverse profile at Lycoming SR 15- southbound, Superpave full section.

Table 6 Measured Rut Depth for Lycoming SR 15 – Northbound.

Rut Depth (mm) Rut Depth (mm)

Distance, ft Left Right Distance, ft Left Right

100 4.5 6.0 500 10.5 3.5

700 5.0 5.0 800 7.5 5.0

1300 4.0 1100 8.0 7.0

1400 6.0 4.5

Average 4.5 5.5 Average 8.0 5.0

Std. Dev. 0.5 0.71 Std. Dev. 1.62 1.27

ID2

Full

Depth

Const.

C.O.V. 11.1 12.9

Superpave

Full

Depth

Const.

C.O.V. 20.3 25.5

28

Table 7 Measured Rut Depth for Lycoming SR 15 – Southbound.



100 8.5 4.5 800 5.0 7.0

200 6.0 3.0 900 7.5 9.0

300 7.0 3.5 1000 6.0 13.5

500 7.0 2.0 1100 6.0 15.0

600 5.5 5.0

Average 6.8 3.6 Average 6.1 11.1

Std. Dev. 1.15 1.19 Std. Dev. 1.03 3.75

Superpave

over

Concrete

C.O.V. 16.9 33.2

Superpave-

Full

Depth

Const.

C.O.V. 16.8 33.7

Pictures showing general appearance of the pavement sections are presented in Figures

13 through 15.

29

Figure 13 Pictures of Lycoming SR 15 pavement – ID2, northbound.

30

Figure 14 Pictures from Lycoming SR 15, Superpave full depth, northbound.

31

Figure 15 Pictures of Lycoming SR 15 pavement, Superpave over concrete, southbound.

32

Evaluation Results for Highway SR 11, Snyder County

Overall, this pavement appeared to be in good shape. A few spots of minor raveling and loss

of fines were observed on the surface.

Cracking

The level of cracking on the mat was found to be limited. No transverse cracks were

observed on this pavement. The total length of sporadic cracks was approximately 110 ft within the

1500-ft length surveyed. Most of this cracking was observed within the right wheel path of the

travel lane.

Major cracking was the continuous longitudinal crack at the construction joint between the passing

and travel lanes, as well as between the travel lane and shoulder. This longitudinal joint crack was

observed throughout most of the 1500-ft length surveyed.

The pavement was also surveyed for a length of 300 ft on the southbound lane, north of Mill

Rd. No distresses were observed except the longitudinal cracking at the joints. Most of the passing

lane within the 300 ft surveyed appeared to be in excellent shape.

Rutting

Figures 16 through 18 and Tables 8 and 9 present rutting results for Snyder SR 11. Rutting

in excess of 12 mm was observed at the vicinity of the 11th Street intersection due to slow-moving

traffic. As we moved farther from the intersection, the rutting decreased. Average rutting observed

at distances away from the intersection was approximately 6 to 7 mm. On average, the left and right

wheel paths indicated similar levels of rutting.

33

Figure 16 Transverse profile at Snyder SR 11- southbound passing lane.

Figure 17 Transverse profile at Snyder SR 11- southbound travel lane.

34

Figure 18 Transverse profile at Snyder SR 11- southbound travel lane.

Table 8 Measured Rut Depth for Snyder SR 11 – Southbound.



50 14.0 13.5 500 5.5 7.5

100 15.0 12.0 400 6.5 7.5

274 8.5 10.0 300 7.0 6.0

308 7.5 8.0 Average 6.3 7.0

500 7.0 7.0 Std. Dev. 0.76 0.87

700 6.5 9.0

Travel

Lane

North Of

Mill

Road

C.O.V. 12.1 12.4

Average 9.8 9.9

Std. Dev. 3.75 2.46

Travel

Lane

North of

11th Street

C.O.V. 38.5 24.8

35

Table 9 Measured Rut Depth for Snyder SR 11- Southbound.

Rut Depth (mm)

Distance, ft Left Right

500 7.0 5.0

400 6.5 4.5

300 6.0 4.5

Average 6.5 4.7

Std. Dev. 0.41 0.29

Passing

Lane

C.O.V. 6.3 6.2

Pictures showing general appearance of the pavement sections for Snyder SR 11 are

presented in Figure 19.

36

Figure 19 Pictures of Snyder SR 11 pavement, southbound.

37

EVALUATION RESULTS FOR SR 153-SECTION 225, CLEARFIELD COUNTY

Cracking

PG 64-22 Section: Cracking appeared dominant in this section. The first 600 ft of the

surveyed section exhibited significant cracking. The amount of cracking at the remaining 500 ft was

considerably lower than the first 600 ft. The width of the cracks was mostly in the range of 3 to 5

mm, but some were as wide as 10 to 17 mm. Longitudinal cracks both in the right and left wheel

paths were obvious, with medium severity (crack width > 6mm). Total length of wheel path

cracking was 227 ft in the right wheel path and 236 ft in the left wheel path. Non-wheel path

longitudinal cracking was measured to be approximately 51 ft, with low severity (crack width <

6mm). Transverse cracks were observed with low severity (crack width < 6mm), but no pattern

could be found, and they were sporadic. Total length of transverse cracks was about 157 ft.

Longitudinal joint cracks between the two lanes was severe, and in some cases very severe, and

continuous for a long stretch of the surveyed section. Of the 1100 ft surveyed, the total length of

longitudinal joint cracking was about 980 ft. Total length of cracking measured (excluding

longitudinal joint cracking) was approximately 735 ft. Cracking was also observed at the

shoulder/lane interface area. These cracks were mostly concentrated on the shoulder at a distance of

about 5 ft from the white stripe, but some were right at the edge close to the stripe. These cracks

were mostly of medium severity, with a total length of about 647 ft. Some of the edge cracks,

however, were very severe.

PG 64-28 Section: For the 1000-ft stretch of the road surveyed for the PG 64-28 section, the

pavement appeared in significantly better condition compared with the PG 64-22 section. There

were no cracks observed on the mat. The pavement for the most part looked very uniform. Only

minor raveling close to the left wheel path (between the center of wheel path and longitudinal

construction joint) was observed in some areas. The only cracking observed on the mat was the

longitudinal cracks in the left wheel path. This was limited as the total length of this low severity

cracking was about 46 ft.

Rutting

While multiple transverse profiles could be obtained for PG 64-22 section, only one

38

relatively meaningful graph for rutting could be obtained for the PG 64-28 section (Figures 20 and

21, and Table 10). Overall, it was observed that the left wheel path rutting was larger for the PG 64-

28 section compared to the PG 64-22 section. Average rutting for both sections was approximately

6 to 7 mm.

39

Figure 20 Transverse profile at Clearfield SR 153- northbound, PG 64-22 section.

Figure 21 Transverse profile at Clearfield SR 153- northbound, PG 64-28 section.

40

Table 10 Measured Rut Depth for Clearfield SR 153-Northbound.



0 6.0 6.5 800 9.5 4.0

200 7.0 4.0 Average 9.5 4.0

400 7.5 9.5 Std. Dev. 0 0

600 5.5 7.0

PG 64-28

C.O.V. 0 0

800 6.0 7.0

Average 6.4 6.8

Std. Dev. 0.82 1.96

PG 64-22

C.O.V. 12.8 28.8

Pictures showing general appearance of the pavement sections at Clearfield SR 153 are

presented in Figures 22 and 23.

42

Figure 22 Pictures of Clearfield SR 153 pavement, PG 64-22 section.

43

Figure 23 Pictures of Clearfield SR 153 pavement, PG 64-28 section.

44

EVALUATION RESULTS FOR I-80, EASTBOUND, CENTRE COUNTY

Cracking

MP 167-167.5: The pavement mat was free of cracks in the section surveyed. No cracks of

any type were found except longitudinal cracks at the white stripe between the travel lane and the

shoulder. This crack was continuous throughout the 1000-ft section surveyed. The cracks were

mostly located 4 to 7 inches to the right of the white stripe.

There was slight raveling and loss of fines observed on the surface in some areas throughout

the pavement; however, the pavement looked uniform and in a relatively good shape.

MP 167.5-168: Overall, this section was similar to the previous section. No cracks of any

kind were found except the edge crack between the travel lane and shoulder throughout the whole

section. Minor loss of fines from the surface was observed; otherwise, the mat looked very uniform.

MP 168-168.5: Similar to the two previous sections, no cracks were observed except the

edge crack discussed previously. Even though loss of fines and raveling was minor, it was more

prominent compared to previous sections. This is probably because the wearing course in this

section was a 19 mm mix, and in the previous two sections, a 12.5 mm mix was used at the surface.

MP 168.5-169: This section was very similar to the first two sections, with minor raveling

present. The crack between the travel lane and shoulder was observed as before except with less

severity in some areas.

MP 169-169.5: This section appeared the best section, with no cracks. Even the cracking

between the travel lane and shoulder were absent in this section. The mat looked uniform.

Rutting

The range of rutting for all sections varied between 2 and 6 mm (Figures 24 through 28, and

Tables 11 through 13) . For all cases, the level of rutting in the left wheel path was larger than that

in the right wheel path. The difference between different sections was in the aggregate size (12.5

mm versus 19 mm for the wearing course and 19 mm versus 25 mm for the binder course) and the

45

layer thickness (40 mm versus 50 mm for the wearing layer and 50 mm versus 75 mm for the binder

layer). From measurements, it can be concluded that none of the sections is manifesting excessive

rutting.

46

Figure 24 Transverse profile at Centre I-80, eastbound, MP 167.0 to MP 167.5.

Figure 25 Transverse profile at Centre I-80, eastbound, MP 167.5 to MP 168.

47


Figure 27 Transverse profile at Centre I-80, eastbound, MP 168.5 to MP 169.

48


Table 11 Measured Rut Depth for Centre I-80, Eastbound.



200 4.5 200 5.0 2.0

400 4.0 3.5 400 5.0 2.0

600 4.5 3.0 600 5.5 2.0

800 5.0 3.5 Average 5.2 2.0

Average 4.5 3.3 Std. Dev. 0.29 0.00

Std. Dev. 0.41 0.29

MP

167.5 to

168.0

C.O.V. 5.6 0.0

MP

167.0 to

167.5

C.O.V. 9.1 8.7

49

Table 12 Meas

Date post:	31-Jan-2021
Category:	Documents
Upload:	others
View:	5 times
Download:	1 times

Field-Focused Superpave Validation...The Superpave design system came into existence in the...

Documents