PREPARED FOR:
California Department of Transportation
Division of Research and Innovation
Office of Roadway Research
PREPARED BY:
University of California
Pavement Research Center
UC Davis, UC Berkeley
July 2008
Research Report: UCPRC- RR- 2008- 11
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Authors:
David Jones, Rongzong Wu, Bor- Wen Tsai,
Qing Lu, and John T. Harvey
Partnered Pavement Research Program ( PPRC) Contract Strategic Plan Element 4: 18:
Warm- Mix Asphalt
UCPRC- RR- 2008- 11 i
DOCUMENT RETRIEVAL PAGE Research Report: UCPRC- RR- 2008- 11
Title: Warm- Mix Asphalt Study: Test Track Construction and First- Level Analysis of Phase 1 HVS and
Laboratory Testing
Authors: David Jones, Rongzong Wu, Bor- Wen Tsai, Qing Lu, and John T. Harvey
Prepared for:
Caltrans
FHWA No:
ca101562a
Work submitted:
December 18, 2008
Date
July 2008
Strategic Plan Element No:
4.18
Status:
Stage 6, Approved, final
Version No.:
1
Abstract:
This first- level report describes the first phase of a warm- mix asphalt study, which compares the performance of a
control mix, produced and constructed at conventional hot- mix asphalt temperatures, with three mixes produced
with warm- mix additives, produced and compacted at approximately 35° C ( 60° F) lower than the control. The
additives tested included Advera WMA ® , Evotherm DATTM, and Sasobit ® . The test track layout and design, mix
design and production, and test track construction are discussed, as well as the results of Heavy Vehicle Simulator
( HVS) and laboratory testing. Key findings from the study include:
• Adequate compaction can be achieved on warm- mixes at lower temperatures.
• Optimal compaction temperatures are likely to differ between the different warm- mix technologies. However, a
temperature reduction of at least 35° C ( 60° F) is possible.
• Based on the results of HVS testing, it is concluded that the use of any of the three warm- mix asphalt
technologies used in this experiment will not significantly influence the rutting performance of the mix.
• Laboratory moisture sensitivity testing indicated that all the mixes tested were potentially susceptible to moisture
damage. There was, however, no difference in the level of moisture sensitivity between the control mix and
mixes with the additives assessed in this study.
• Laboratory fatigue testing indicated that the warm- mix technologies used in this study will not influence the
fatigue performance of a mix.
• Quality control checks on the mix immediately after production revealed that lower specific gravities and higher
air- void contents were recorded on the warm mixes.
• The cost benefits of using the warm- mix technologies could not be assessed in this study due to the very small
quantities produced.
The HVS and laboratory testing completed in this phase have provided no results to suggest that warm- mix
technologies should not be used in California. Final recommendations on the use of this technology will only be
made after further research and monitoring of full- scale pilot studies on in- service pavements is completed. Interim
recommendations include:
• The use of warm- mix technologies should continue in full- scale pilot studies on in- service pavements.
• HVS testing to assess moisture sensitivity should continue to confirm the laboratory findings.
• Laboratory testing on laboratory- mixed, laboratory- compacted specimens should proceed to determine whether
representative mixes can be produced in the laboratory and to determine how and whether test results differ from
field- mixed, field- compacted specimens.
Keywords:
Warm- mix asphalt, WMA, accelerated pavement testing, Heavy Vehicle Simulator
Proposals for implementation:
Continue with Phase 2 moisture sensitivity testing. Continue with implementation in pilot studies.
Related documents:
Work plan, UCPRC- WP- 2007- 01.
Signatures:
D. Jones
1st Author
J. Harvey
Technical Review
D. Spinner
Editor
J. Harvey
Principal Investigator
T. J. Holland
Caltrans Contract Manager
ii UCPRC- RR- 2008- 11
UCPRC- RR- 2008- 11 iii
DISCLAIMER
The contents of this report reflect the views of the authors who are responsible for the facts and accuracy
of the data presented herein. The contents do not necessarily reflect the official views or policies of the
State of California or the Federal Highway Administration. This report does not constitute a standard,
specification, or regulation.
PROJECT OBJECTIVES
The objective of this project is to determine whether the use of additives to reduce the production and
construction temperatures of hot- mix asphalt influences performance of the mix. This will be achieved
through the following tasks:
1. Preparation of a workplan to guide the research;
2. Monitoring the construction of Heavy Vehicle Simulator ( HVS) and in- service test sections;
3. Sampling of mix and mix components during asphalt concrete production and construction;
4. Trafficking of demarcated sections with the HVS in a series of tests to assess performance;
5. Conducting laboratory tests to identify comparable laboratory performance measures;
6. Monitoring the performance of in- service pilot sections; and
7. Preparation of first- and second- level analysis reports and a summary report detailing the
experiment and the findings.
This report covers Tasks 2, 3, 4, 5, and 7.
iv UCPRC- RR- 2008- 11
ACKNOWLEDGEMENTS
The University of California Pavement Research Center acknowledges the following individuals and
organizations who contributed to the project:
 Ms. Terrie Bressette, Ms. Cathrina Barros, Mr. Glenn Johnson, and Dr. Joe Holland, Caltrans
 Mr. Mike Cook and Dr. Hongbin Xie, Graniterock Company
 The management and staff, Graniterock Company and Pavex Construction
 Ms. Annette Smith, PQ Corporation
 Dr. Everett Crews, Meadwestvaco
 Mr. John Shaw and Mr. Larry Michael, Sasol Wax Americas
 Mr. Matthew Corrigan and Mr. Satish Bellaguti, Federal Highway Administration Turner Fairbanks
Highway Research Center
UCPRC- RR- 2008- 11 v
EXECUTIVE SUMMARY
The first phase of a comprehensive study into the use of warm- mix asphalt has been completed for the
California Department of Transportation ( Caltrans) by the University of California Pavement Research
Center ( UCPRC). The study, based on a work plan approved by Caltrans, included the identification of an
appropriate site for the experiment, the design and construction of a test track, an accelerated loading test
using the Heavy Vehicle Simulator ( HVS) to assess rutting behavior, and a series of laboratory tests on
specimens sampled from the test track. The objective of the study is to determine whether the use of
additives to reduce the production and construction temperatures of asphalt concrete influences
performance of the mix. The study compared the performance of a control mix, produced and constructed
at conventional hot- mix asphalt temperatures, with three warm- mixes, produced and compacted at
approximately 35° C ( 60° F) lower than the control. The additives tested included Advera WMA ® ,
Evotherm DATTM, and Sasobit ® .
The test track is located at the Graniterock Company's A. R. Wilson Quarry and Asphalt Plant near
Aromas, California. The design and construction of the test track was a cooperative effort between
Caltrans, the UCPRC, Graniterock, and the three warm- mix technology suppliers. The test track is 80 m
by 8.0 m ( 262 ft by 26 ft) divided into four test sections ( Control, Advera, Evotherm, and Sasobit). The
pavement structure consists of the existing subgrade/ subbase material overlying bedrock, with 300 mm
( 12 in.) of imported aggregate base, and two 60 mm ( 2.4 in.) lifts of asphalt concrete. A standard mix
design was used and no adjustments were made to accommodate the additives. Target production
temperatures for the Control mix were set at 155° C ( 310° F) and at 120° C ( 250° F) for the warm- mixes.
The test track was constructed in September 2007, using asphalt from the commercial asphalt mix plant at
the quarry. Specimens were removed from the test track for laboratory testing.
The first phase of Heavy Vehicle Simulator ( HVS) testing commenced in October 2007 after a six- week
curing period and was completed in April 2008. This testing compared early rutting performance at
elevated temperatures ( pavement temperature of 50° C at 50 mm [ 122° F at 2.0 in.]), using a 40 kN
( 9,000 lb) load on a standard dual wheel configuration and a unidirectional trafficking mode. Laboratory
testing commenced in December 2007 and was completed in July 2008. The test program included shear
testing, wet and dry fatigue testing, Hamburg Wheel- Track testing, and determination of the wet- to- dry
tensile strength ratio. The results of this testing will be used to identify subsequent research needs.
vi UCPRC- RR- 2008- 11
Key findings from the study include:
 A Hveem mix design that met Caltrans requirements for Type A 19 mm maximum dense- graded
asphalt concrete was used in the study. The target gradation met Caltrans requirements for both the
Coarse and Medium gradations. The recommended bitumen content was 5.1 to 5.4 percent by mass
of aggregate, which was based on the minimum air- void content under standard kneading
compaction. The mix design had very high Hveem stabilities.
 A consistent base- course was constructed on the test track using material produced at the nearby
quarry. Some overwatering occurred in the early stages of construction resulting in some moist
areas in the pavement, which influenced measured densities and deflections. These areas are
unlikely to effect later performance of the test track. The very stiff base is likely to complicate any
planned fatigue cracking experiments in that a very high number of HVS repetitions will likely be
required before any distress occurs.
 Minimal asphalt plant modifications were required to accommodate the warm- mix additives.
 No problems were noted with producing the asphalt mixes at the lower temperatures. The target
mix production temperatures ( i. e., 155° C and 120° C [ 310° F and 250° F]) were achieved.
 Although a PG 64- 16 asphalt binder was specified in the work plan, subsequent tests by the Federal
Highway Administration indicated that the binder was rated as PG 64- 22. This should not affect the
outcome of the experiment. After mixing Advera and Sasobit to the binder, the PG grading changed
from PG 64- 22 to PG 70- 22. The addition of Evotherm did not alter the PG grade.
 The Control, Advera, and Evotherm mixes met the project mix design requirements. The binder
content of the Sasobit mix was 0.72 percent below the target binder content and 0.62 percent below
the lowest permissible binder content. This probably influenced performance and was taken into
consideration when interpreting the HVS and laboratory test results presented in this report.
 Graniterock Company did not perform Hveem compaction or stability tests for quality control
purposes as there is no protocol for adjusting the standard kneading compaction temperature for
mixes with warm- mix additives. Instead, Marshall and Superpave Gyratory compaction were
performed in the Graniterock laboratory next to the asphalt plant on mix taken from the silo.
 Laboratory quality control tests on the Control mix ( specimens compacted with Marshall and
Superpave Gyratory compaction) had a higher specific gravity and lower air- void content,
compared to the mixes with additives. It is not clear whether this was a testing inconsistency or is
linked to the lower production and specimen preparation temperatures. This will need to be
investigated during Phase 2 laboratory investigations.
 Moisture contents of the mixes with additives were notably higher than in the Control mix,
indicating that potentially less moisture will evaporate from the aggregate at lower production
temperatures. All mixes were, however, well within the minimum Caltrans- specified moisture
UCPRC- RR- 2008- 11 vii
content level. Aggregate moisture contents will need to be controlled in the stockpiles and
maximum moisture contents may need to be set prior to mix production when using warm- mix
technologies.
 Construction procedures and final pavement quality did not appear to be influenced by the lower
construction temperatures. The Advera mix showed no evidence of tenderness, and acceptable
compaction was achieved. Some tenderness was noted on the Evotherm and Sasobit sections
resulting in shearing under the rollers at various stages of breakdown and/ or rubber- tired rolling,
indicating that the compaction temperatures were still higher than optimal. No problems were
observed after final rolling at lower temperatures.
 Interviews with the paving crew after construction revealed that no problems were experienced
with construction at the lower temperatures. Improved working conditions were identified as an
advantage. Tenderness on the Evotherm and Sasobit sections was not considered as being
significantly different from that experienced with conventional mixes during normal construction
activities.
 Although temperatures at the beginning of compaction on the warm- mix sections were
considerably lower than the Caltrans- specified limits, the temperatures recorded on completion of
compaction were within limits, indicating that the rate of temperature loss in the mixes with
additives was lower than that on the Control mix, as expected.
 Some haze/ smoke was evident on the Control mix during transfer of the mix from the truck to the
paver. No haze or smoke was observed on the mixes with additives.
 Average air- void contents on the Control and Advera sections were 5.6 percent and 5.4 percent
respectively. Those on the Evotherm and Sasobit sections, which showed signs of tenderness
during rolling, were approximately 7.0 percent, with the caveat that the Sasobit mix binder content
was lower than the target while that for the Evotherm sections was not. Based on these
observations, it was concluded that adequate compaction can be achieved on warm- mixes at the
lower temperatures. Optimal compaction temperatures are likely to differ between the different
warm- mix technologies.
 Skid resistance measurements indicated that the warm- mix additives tested do not influence the
skid resistance of an asphalt mix.
 HVS trafficking on each of the four sections revealed that the duration of the embedment phases
( high early- rutting phase of typical two- phase rutting processes) on the Advera and Evotherm
sections were similar to the Control. However, the rut depths at the end of the embedment phases
on these two sections was slightly higher than the Control, which was attributed to less oxidation of
the binder during mix production at lower temperatures. Rutting behavior on the warm- mix
sections followed similar trends to the Control after the embedment phase. The performance of the
viii UCPRC- RR- 2008- 11
Sasobit section could not be directly compared with the other three sections given that the binder
content of the mix was significantly lower.
 Laboratory test results indicate that use of the warm- mix technologies assessed in this study does
not significantly influence the performance of the asphalt concrete when compared to control
specimens produced and compacted at conventional hot- mix asphalt temperatures. However,
moisture sensitivity testing indicated that all the mixes tested were potentially susceptible to
moisture damage. There was, however, no difference in the level of moisture sensitivity between
the Control mix and mixes with warm- mix additives.
The HVS and laboratory testing completed in this phase have provided no results to suggest that warm-mix
technologies should not be used in California. Final recommendations on the use of this technology
will only be made after further research and monitoring of full- scale pilot studies on in- service pavements
is completed. Interim recommendations include the following:
 The use of warm- mix technologies should continue in full- scale pilot studies on in- service
pavements.
 Although laboratory testing indicated that the warm- mix technologies assessed in this study did not
increase the moisture sensitivity of the mix, HVS testing to assess moisture sensitivity should
continue as recommended in the work plan to confirm these findings. Subsequent laboratory testing
of moisture sensitivity should assess a range of different aggregates given that all of the mixes
tested in this study where considered to be moisture sensitive.
 Phase 2 laboratory testing on laboratory- mixed, laboratory- compacted specimens should proceed to
determine whether representative mixes can be produced in the laboratory and to determine how
and whether laboratory test results on these specimens differ from those on field- mixed, field-compacted
specimens.
 As part of the Phase 2 laboratory study, protocols need to be developed for adjusting laboratory
specimen- preparation compaction temperatures for mixes with warm- mix additives. It is unlikely
that any national studies will develop these protocols for Hveem mix designs, which are still used
in California.
UCPRC- RR- 2008- 11 ix
TABLE OF CONTENTS
EXECUTIVE SUMMARY ......................................................................................................................... v
LIST OF TABLES ............................................................................................................................... ... xiii
LIST OF FIGURES ............................................................................................................................... ... xv
LIST OF ABBREVIATIONS ............................................................................................................... xviii
LIST OF TEST METHODS AND SPECIFICATIONS........................................................................ xix
CONVERSION FACTORS ...................................................................................................................... xx
1. INTRODUCTION ............................................................................................................................. 1
1.1 Background ............................................................................................................................... 1
1.2 Project Objectives..................................................................................................................... 1
1.3 Overall Project Organization..................................................................................................... 2
1.3.1 Deliverables .................................................................................................................. 4
1.4 Structure and Content of this Report ......................................................................................... 4
1.5 Measurement Units.................................................................................................................... 5
1.6 Terminology .............................................................................................................................. 5
2. TEST TRACK LOCATION, DESIGN, AND CONSTRUCTION ............................................... 7
2.1 Experiment Location ................................................................................................................. 7
2.2 Pavement Design..................................................................................................................... 10
2.2.1 Layer Thickness .......................................................................................................... 10
2.2.2 Mix Design.................................................................................................................. 11
2.2.3 Production and Construction Temperatures................................................................ 12
2.3 Test Track Layout ................................................................................................................... 12
2.4 Test Track Preparation ............................................................................................................ 12
2.5 Base- Course Construction....................................................................................................... 14
2.5.1 Equipment ................................................................................................................... 14
2.5.2 Construction ................................................................................................................ 14
2.5.3 Instrumentation ........................................................................................................... 15
2.5.4 Construction Quality Control...................................................................................... 16
2.6 Asphalt Concrete Production................................................................................................... 25
2.6.1 Plant Modifications ..................................................................................................... 25
2.6.2 Mix Production ........................................................................................................... 25
2.6.3 Quality Control ........................................................................................................... 27
2.7 Asphalt Concrete Placement ................................................................................................... 31
2.7.1 Placement.................................................................................................................... 31
2.7.2 Instrumentation ........................................................................................................... 38
2.7.3 Quality Control ........................................................................................................... 39
2.8 Sampling....................................................................................................................... .......... 53
2.8.1 Samples for Laboratory- Mixed, Laboratory- Compacted Specimen Testing .............. 53
2.8.2 Samples for Field- Mixed, Laboratory- Compacted Specimen Testing........................ 53
2.8.3 Field- Mixed, Field- Compacted Samples .................................................................... 55
2.9 Construction Summary............................................................................................................ 55
3. TEST TRACK LAYOUT AND HVS TEST CRITERIA............................................................. 59
3.1 Protocols...................................................................................................................... ........... 59
3.2 Test Track Layout ................................................................................................................... 59
3.3 HVS Test Section Layout........................................................................................................ 59
3.4 Pavement Instrumentation and Monitoring Methods .............................................................. 59
3.5 HVS Test Criteria.................................................................................................................... 62
3.5.1 Test Section Failure Criteria ....................................................................................... 62
3.5.2 Environmental Conditions .......................................................................................... 62
3.5.3 Test Duration............................................................................................................... 62
3.5.4 Loading Program......................................................................................................... 62
4. PHASE 1 HVS TEST DATA SUMMARY.................................................................................... 65
x UCPRC- RR- 2008- 11
4.1 Introduction ............................................................................................................................. 65
4.2 Rainfall ............................................................................................................................... .... 66
4.3 Section 600FD: Control.......................................................................................................... 67
4.3.1 Test Summary ............................................................................................................. 67
4.3.2 Outside Air Temperatures ........................................................................................... 67
4.3.3 Air Temperatures in the Temperature Control Unit.................................................... 68
4.3.4 Temperatures in the Asphalt Concrete Layers ............................................................ 68
4.3.5 Permanent Surface Deformation ( Rutting) ................................................................. 70
4.3.6 Visual Inspection......................................................................................................... 72
4.4 Section 601FD: Advera .......................................................................................................... 73
4.4.1 Test Summary ............................................................................................................. 73
4.4.2 Outside Air Temperatures ........................................................................................... 74
4.4.3 Air Temperatures in the Temperature Control Unit.................................................... 74
4.4.4 Temperatures in the Asphalt Concrete Layers ............................................................ 75
4.4.5 Permanent Surface Deformation ( Rutting) ................................................................. 76
4.4.6 Visual Inspection......................................................................................................... 78
4.5 Section 602FD: Evotherm ...................................................................................................... 79
4.5.1 Test Summary ............................................................................................................. 79
4.5.2 Outside Air Temperatures ........................................................................................... 79
4.5.3 Air Temperatures in the Temperature Control Unit.................................................... 80
4.5.4 Temperatures in the Asphalt Concrete Layers ............................................................ 80
4.5.5 Permanent Surface Deformation ( Rutting) ................................................................. 82
4.5.6 Visual Inspection......................................................................................................... 85
4.6 Section 603FD: Sasobit .......................................................................................................... 85
4.6.1 Test Summary ............................................................................................................. 85
4.6.2 Outside Air Temperatures ........................................................................................... 86
4.6.3 Air Temperatures in the Temperature Control Unit.................................................... 86
4.6.4 Temperatures in the Asphalt Concrete Layers ............................................................ 88
4.6.5 Permanent Surface Deformation ( Rutting) ................................................................. 89
4.6.6 Visual Inspection......................................................................................................... 89
4.7 Test Summary........................................................................................................................ . 92
5. PHASE 1 LABORATORY TEST DATA SUMMARY................................................................ 95
5.1 Experiment Design .................................................................................................................. 95
5.1.1 Shear Testing............................................................................................................... 95
5.1.2 Fatigue Testing............................................................................................................ 96
5.1.3 Moisture Sensitivity Testing ....................................................................................... 97
5.2 Test Results ............................................................................................................................. 97
5.2.1 Shear Tests .................................................................................................................. 97
5.2.2 Resilient Shear Modulus ( G)....................................................................................... 98
5.2.3 Fatigue Beam Tests................................................................................................... 103
5.2.4 Moisture Sensitivity: Hamburg Wheel- Track Test .................................................. 113
5.2.5 Moisture Sensitivity: Tensile Strength Retained ( TSR)........................................... 119
5.3 Summary of Laboratory Testing Results............................................................................... 121
6. CONCLUSIONS AND RECOMMENDATIONS....................................................................... 123
6.1 Conclusions ........................................................................................................................... 123
6.1.1 Comparative Energy Usage....................................................................................... 125
6.1.2 Achieving Compaction Density at Lower Temperatures.......................................... 125
6.1.3 Optimal Temperature Ranges for Warm- Mixes........................................................ 125
6.1.4 Cost Implications ...................................................................................................... 125
6.1.5 Rutting Performance ................................................................................................. 126
6.1.6 Moisture Sensitivity .................................................................................................. 126
6.1.7 Fatigue Performance ................................................................................................. 126
6.1.8 Other Effects ............................................................................................................. 126
UCPRC- RR- 2008- 11 xi
6.1.9 Rubberized and Open- Graded Mixes........................................................................ 126
6.2 Recommendations ................................................................................................................. 126
7. REFERENCES .............................................................................................................................. 129
APPENDIX A: MIX DESIGN EXAMPLES ..................................................................................... 131
APPENDIX B: BINDER COMPLIANCE CERTIFICATE ............................................................ 137
APPENDIX C: FATIGUE BEAM SOAKING PROCEDURE........................................................ 139
xii UCPRC- RR- 2008- 11
UCPRC- RR- 2008- 11 xiii
LIST OF TABLES
Table 2.1: Summary of Centerline DCP Survey........................................................................................ 10
Table 2.2: Key Mix Design Parameters ..................................................................................................... 12
Table 2.3: Summary of Base- Course Density Measurements after 7- day Dry Back................................. 19
Table 2.4: Summary of Base- Course Moisture Content Measurements after 7- day Dry Back ................. 19
Table 2.5: Summary of Base- Course LWD Measurements....................................................................... 22
Table 2.6: Summary of FWD Measurements on the Base- Course ............................................................ 23
Table 2.7: Summary of Mix Production Observations .............................................................................. 27
Table 2.8: Summary of Binder Performance- Grade Test Results.............................................................. 28
Table 2.9: Quality Control of Mix After Production ................................................................................. 29
Table 2.10: Strain Gauge Position Detail................................................................................................... 39
Table 2.11: Summary of Temperature Measurements............................................................................... 41
Table 2.12: Summary of Asphalt Concrete Density Measurements .......................................................... 47
Table 2.13: Summary of FWD Measurements .......................................................................................... 48
Table 2.14: Results of Skid Resistance Testing......................................................................................... 52
Table 3.1: Test Duration for Phase 1 HVS Rutting Tests .......................................................................... 62
Table 3.2: Summary of HVS Loading Program ........................................................................................ 63
Table 4.1: 600FD: Temperature Summary for Air and Pavement............................................................ 69
Table 4.2: 601FD: Temperature Summary for Air and Pavement............................................................ 75
Table 4.3: 602FD: Temperature Summary for Air and Pavement............................................................ 81
Table 4.4: 603FD: Temperature Summary for Air and Pavement............................................................ 88
Table 5.1: Summary of Air- Void Contents of Shear Test Specimens ....................................................... 97
Table 5.2: Summary of Ln( G*) Master Curves ....................................................................................... 101
Table 5.3: Summary of Phase Angle Master Curves ............................................................................... 101
Table 5.4: Summary of Air- Void Contents of Fatigue Beam Specimens................................................ 103
Table 5.5: Summary of Air- Void Contents of Flexural Frequency Sweep Specimens ........................... 103
Table 5.6: Air- Void Content Comparison of Top and Bottom Lifts........................................................ 105
Table 5.7: Summary of Master Curves and Time- Temperature Relationships........................................ 109
Table 5.8: Air- Void Content of Hamburg Wheel- Track Test Specimens................................................ 113
Table 5.9: Test Result Summary of Average Rut Progression Curves .................................................... 118
Table 5.10: Test Result Summary of Maximum Rut Progression Curves ............................................... 118
Table 5.11: Air- Void Content of TSR Test Specimens ........................................................................... 120
Table 5.12: Summary of TSR Test Results.............................................................................................. 120
xiv UCPRC- RR- 2008- 11
UCPRC- RR- 2008- 11 xv
LIST OF FIGURES
Figure 2.1: General location of test track site............................................................................................... 7
Figure 2.2: Location of the test track site at the A. R. Wilson Quarry.......................................................... 8
Figure 2.3: Site layout. ............................................................................................................................... . 9
Figure 2.4: Site prior to construction............................................................................................................ 9
Figure 2.5: Pavement structure for warm- mix asphalt test sections........................................................... 11
Figure 2.6: Test track layout....................................................................................................................... 13
Figure 2.7: K- rail placement and subgrade/ subbase preparation. .............................................................. 13
Figure 2.8: Base- course construction. ........................................................................................................ 14
Figure 2.9: Overwatering during base- course construction........................................................................ 15
Figure 2.10: Installation of moisture sensors. ............................................................................................ 16
Figure 2.11: Completed base- course showing tightly bound surface......................................................... 16
Figure 2.12: Isolated areas of distress on the base- course.......................................................................... 17
Figure 2.13: Base- course density and deflection measurement plan.......................................................... 18
Figure 2.14: Summary of average dry density ( backscatter)...................................................................... 20
Figure 2.15: Summary of average dry density at various depths ( probe)................................................... 20
Figure 2.16: Summary of moisture content at different depths ( probe). .................................................... 21
Figure 2.17: Summary of average LWD deflection by section.................................................................. 22
Figure 2.18: Summary of LWD base- course deflection measurements ( D1 geophone)............................ 23
Figure 2.19: Summary of average FWD deflection by section. ................................................................. 24
Figure 2.20: Summary of FWD base- course deflection measurements ( D1 geophone). ........................... 24
Figure 2.21: Summary of FWD subgrade deflection measurements ( D6 geophone)................................. 25
Figure 2.22: Plant modifications for admixtures........................................................................................ 26
Figure 2.23: Advera supply system............................................................................................................ 26
Figure 2.24: Evotherm supply system. ....................................................................................................... 26
Figure 2.25: Sasobit mixing. ...................................................................................................................... 26
Figure 2.26: Water spray prior to priming.................................................................................................. 32
Figure 2.27: Prime application. .................................................................................................................. 32
Figure 2.28: Damage to prime by vehicle and foot traffic. ........................................................................ 32
Figure 2.29: Control: Placement of first lift of asphalt concrete. .............................................................. 33
Figure 2.30: Control: Pick up during rubber- tire rolling........................................................................... 34
Figure 2.31: Advera: Mix delivery, no haze.............................................................................................. 35
Figure 2.32: Advera: Surface after final rolling. ....................................................................................... 35
Figure 2.33: Evotherm: Damage behind paver.......................................................................................... 35
Figure 2.34: Evotherm: Damage repair. .................................................................................................... 35
Figure 2.35: Evotherm: Shear after rubber- tired roller.............................................................................. 36
Figure 2.36: Evotherm: Surface after final rolling. ................................................................................... 36
Figure 2.37: Sasobit: Shearing during breakdown rolling......................................................................... 36
Figure 2.38: Sasobit: Pick up during rubber- tire rolling. .......................................................................... 36
Figure 2.39: Sasobit: Surface after final rolling. ....................................................................................... 37
Figure 2.40: Sasobit: Shearing during final rolling. .................................................................................. 37
Figure 2.41: Tack coat application ( Control). ............................................................................................ 37
Figure 2.42: Tack coat application ( Sasobit).............................................................................................. 37
Figure 2.43: Strain gauge layout. ............................................................................................................... 39
Figure 2.44: Strain gauge covered with mix. ............................................................................................. 39
Figure 2.45: Summary of temperature measurements ( first lift). ............................................................... 42
Figure 2.46: Summary of temperature measurements ( second lift). .......................................................... 42
Figure 2.47: Thermal images of test track during construction.................................................................. 43
Figure 2.48: Asphalt concrete density measurement plan.......................................................................... 47
Figure 2.49: Summary of average deflection by section............................................................................ 48
xvi UCPRC- RR- 2008- 11
Figure 2.50: Summary of Sensor- 1 deflection measurements on asphalt concrete surface. ...................... 49
Figure 2.51: Summary of subbase/ subgrade deflection measurements ( D6 geophone)............................. 49
Figure 2.52: Caltrans Portable Skid Tester................................................................................................. 50
Figure 2.53: Dynamic Friction Tester. ....................................................................................................... 50
Figure 2.54: Circular Track Meter. ............................................................................................................ 50
Figure 2.55: Preparation of field- mixed, laboratory- compacted specimens. ............................................. 54
Figure 2.56: Test track sampling plan and sample removal. ...................................................................... 56
Figure 3.1: Layout of test track and HVS test sections. ............................................................................. 60
Figure 3.2: Phase 1 test section layout and location of thermocouples. ..................................................... 61
Figure 4.1: Illustration of maximum rut depth and average deformation of a leveled profile. .................. 65
Figure 4.2: Measured rainfall during Phase 1 HVS testing........................................................................ 66
Figure 4.3: 600FD: Load history............................................................................................................... 67
Figure 4.4: 600FD: Daily average outside air temperatures...................................................................... 68
Figure 4.5: 600FD: Daily average inside air temperatures........................................................................ 69
Figure 4.6: 600FD: Daily average temperatures at pavement surface and various depths........................ 70
Figure 4.7: 600FD: Profilometer cross section at various load repetitions. .............................................. 71
Figure 4.8: 600FD: Average maximum rut. .............................................................................................. 71
Figure 4.9: 600FD: Average deformation. ................................................................................................ 72
Figure 4.10: 600FD: Contour plot of permanent surface deformation at end of test. ............................... 72
Figure 4.11: 600FD: Section photograph at test completion..................................................................... 73
Figure 4.12: 601FD: Load history............................................................................................................. 73
Figure 4.13: 601FD: Daily average outside air temperatures.................................................................... 74
Figure 4.14: 601FD: Daily average inside air temperatures...................................................................... 75
Figure 4.15: 601FD: Daily average temperatures at pavement surface and various depths...................... 76
Figure 4.16: 601FD: Profilometer cross section at various load repetitions. ............................................ 77
Figure 4.17: 601FD: Average maximum rut. ............................................................................................ 77
Figure 4.18: 601FD: Average deformation. .............................................................................................. 78
Figure 4.19: 601FD: Contour plot of permanent surface deformation at end of test. ............................... 78
Figure 4.20 602FD: Load history. ............................................................................................................. 79
Figure 4.21: 602FD: Daily average outside air temperatures.................................................................... 80
Figure 4.22: 602FD: Daily average inside air temperatures...................................................................... 81
Figure 4.23: 602FD: Daily average temperatures at pavement surface and various depths...................... 82
Figure 4.24: 602FD: Profilometer cross section at various load repetitions. ............................................ 83
Figure 4.25: 602FD: Average maximum rut. ............................................................................................ 83
Figure 4.26: 602FD: Average deformation. .............................................................................................. 84
Figure 4.27: 602FD: Contour plot of permanent surface deformation at end of test. ............................... 84
Figure 4.28: 602FD: Section photographs at test completion. .................................................................. 85
Figure 4.29: 603FD: Load history............................................................................................................. 86
Figure 4.30: 603FD: Daily average outside air temperatures.................................................................... 87
Figure 4.31: 603FD: Daily average inside air temperatures...................................................................... 87
Figure 4.32: 603FD: Daily average temperatures at pavement surface and various depths...................... 88
Figure 4.33: 603FD: Profilometer cross section at various load repetitions. ............................................ 90
Figure 4.34: 603FD: Average maximum rut. ............................................................................................ 90
Figure 4.35: 603FD: Average deformation. .............................................................................................. 91
Figure 4.36: 603FD: Contour plot of permanent surface deformation at end of test. ............................... 91
Figure 4.37: Comparison of average maximum rut.................................................................................... 92
Figure 4.38: Comparison of average deformation...................................................................................... 93
Figure 5.1: Air- void contents of shear specimens. ..................................................................................... 98
Figure 5.2: Summary boxplots of resilient shear modulus......................................................................... 98
Figure 5.3: Summary boxplots of cycles to 5% permanent shear strain. ................................................... 99
Figure 5.4: Summary boxplots of cumulative permanent shear strain at 5,000 cycles. ........................... 100
Figure 5.5: Summary of shear complex modulus master curves.............................................................. 102
Figure 5.6: Summary of shear phase angle master curves. ...................................................................... 102
UCPRC- RR- 2008- 11 xvii
Figure 5.7: Air- void contents of fatigue beam specimens ( dry and wet). ................................................ 104
Figure 5.8: Air- void contents of flexural frequency sweep specimens ( dry and wet).............................. 104
Figure 5.9: Summary boxplots of initial stiffness. ................................................................................... 105
Figure 5.10: Summary boxplots of initial phase angle............................................................................. 106
Figure 5.11: Summary boxplots of fatigue life. ....................................................................................... 107
Figure 5.12: Complex modulus ( E*) master curves ( dry). ....................................................................... 110
Figure 5.13: Temperature- shifting relationship ( dry)............................................................................... 110
Figure 5.14: Complex modulus ( E*) master curves ( wet)........................................................................ 111
Figure 5.15: Temperature- shifting relationship ( wet). ............................................................................. 111
Figure 5.16: Comparison of dry and wet complex modulus master curves. ............................................ 112
Figure 5.17: Maximum and average rut progression curves for Control and Advera specimens. ........... 114
Figure 5.18: Maximum and average rut progression curves for Evotherm and Sasobit specimens......... 115
Figure 5.19: Control mix specimens after Hamburg Wheel- Track Test. ................................................. 116
Figure 5.20: Advera specimens after Hamburg Wheel- Track Test.......................................................... 116
Figure 5.21: Evotherm specimens after Hamburg Wheel- Track Test...................................................... 117
Figure 5.22: Sasobit specimens after Hamburg Wheel- Track Test.......................................................... 117
Figure 5.23: Air- void content versus indirect tensile strength. ................................................................ 121
xviii UCPRC- RR- 2008- 11
LIST OF ABBREVIATIONS
AASHTO American Association of State Highway and Transport Officials
ASTM American Society for Testing and Materials
Caltrans California Department of Transportation
CTM Circular Track Meter
DCP Dynamic Cone Penetrometer
DFT Dynamic Friction Tester
DGAC Dense- graded asphalt concrete
ESAL Equivalent standard axle load
FHWA Federal Highway Administration
FMFC Field- mixed, field- compacted
FMLC Field- mixed, laboratory- compacted
FWD Falling Weight Deflectometer
HMA Hot- mix asphalt
HVS Heavy Vehicle Simulator
IFI International Friction Index
LMLC Laboratory- mixed, laboratory- compacted
LWD Light Weight Deflectometer
MDD Multi- Depth Deflectometer
MPD Mean profile depth
PIARC International Association of Road Congresses
PPRC Partnered Pavement Research Center
RHMA- G Gap- graded rubberized hot- mix asphalt
RSD Road Surface Deflectometer
SN Skid number
SPE Strategic Plan Element
TSR Tensile strength retained
UCPRC University of California Pavement Research Center
WMA Warm- mix asphalt
UCPRC- RR- 2008- 11 xix
LIST OF TEST METHODS AND SPECIFICATIONS
AASHTO M- 320 Standard Specification for Performance Graded Asphalt Binder
AASHTO T- 166 Bulk Specific Gravity of Compacted Asphalt Mixtures
AASHTO T- 209 Theoretical Maximum Specific Gravity and Density of Bituminous Paving Mixtures
AASHTO T- 245 Standard Method of Test for Resistance to Plastic Flow of Bituminous Mixtures
Using Marshall Apparatus
AASHTO T- 275 Standard Method of Test for Bulk Specific Gravity of Compacted Bituminous
Mixtures Using Paraffin- Coated Specimens
AASHTO T- 308 Standard Method of Test for Determining the Asphalt Binder Content of Hot Mix
Asphalt ( HMA) by the Ignition Method
AASHTO T- 320 Standard Method of Test for Determining the Permanent Shear Strain and Stiffness
of Asphalt Mixtures using the Superpave Shear Tester
AASHTO T- 321 Flexural Controlled- Deformation Fatigue Test
AASHTO T- 324 Standard Method of Test for Hamburg Wheel- Track Testing of Compacted Hot- Mix
Asphalt ( HMA)
ASTM E 274- 97 Standard Test Method for Skid Resistance of Paved Surfaces Using a Full- Scale Tire
ASTM E 1845- 96 Standard Test Practice for Calculating Pavement Macrotexture Mean Profile Depth
ASTM E 1911- 02 Standard Test Method for Measuring Paved Surface Frictional Properties Using the
Dynamic Friction Tester
ASTM E 1960- 03 Standard Practice for Calculating International Friction Index of a Pavement Surface
ASTM E 2157- 01 Standard Test Method for Measuring Pavement Macrotexture Properties Using the
Circular Track Meter
CT 342 Method of Test for Surface Skid Resistance with the California Portable Skid Tester
CT 366 Method of Test for Stabilometer Value
CT 371 Method of Test for Resistance of Compacted Bituminous Mixture to Moisture
Induced Damage
xx UCPRC- RR- 2008- 11
CONVERSION FACTORS
SI* ( MODERN METRIC) CONVERSION FACTORS
Symbol Convert From Convert To Symbol Conversion
LENGTH
mm millimeters inches in mm x 0.039
m meters feet ft m x 3.28
km kilometers mile mile km x 1.609
AREA
mm2 square millimeters square inches in2 mm2 x 0.0016
m2 square meters square feet ft2 m2 x 10.764
VOLUME
m3 cubic meters cubic feet ft3 m3 x 35.314
kg/ m3 kilograms/ cubic meter pounds/ cubic feet lb/ ft3 kg/ m3 x 0.062
L liters gallons gal L x 0.264
L/ m2 liters/ square meter gallons/ square yard gal/ yd2 L/ m2 x 0.221
MASS
kg kilograms pounds lb kg x 2.202
TEMPERATURE ( exact degrees)
C Celsius Fahrenheit F ° C x 1.8 + 32
FORCE and PRESSURE or STRESS
N newtons poundforce lbf N x 0.225
kPa kilopascals poundforce/ square inch lbf/ in2 kPa x 0.145
* SI is the symbol for the International System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E380.
( Revised March 2003)
UCPRC- RR- 2008- 11 1
1. INTRODUCTION
1.1 Background
Warm- mix asphalt is a relatively new technology. It has been developed in response to needs for reduced
energy consumption and stack emissions during the production of asphalt concrete, lower placement
temperatures, improved workability, and better working conditions for plant and paving crews. Studies in
the United States and Europe indicate that significant reductions in production and placement
temperatures are possible ( 1,2).
Research initiatives on warm- mix asphalt are currently being conducted in a number of states, as well as
by the Federal Highway Administration and the National Center for Asphalt Technology. Accelerated
pavement testing experiments are being carried out on warm- mix asphalt in Ohio and Alabama.
The California Department of Transportation ( Caltrans) has expressed interest in warm- mix asphalt with a
view to reducing stack emissions at plants, to allow longer haul distances between asphalt plants and
construction projects, to improve construction quality ( especially during nighttime closures), and to extend
the annual period for paving. However, the use of warm- mix asphalt technology requires the addition of
an additive into the mix, and/ or changes in production and construction procedures, specifically related to
temperature, which could influence the short- and long- term performance of the pavement. Therefore,
research is required to address a range of concerns related to these changes before statewide
implementation of the technology is approved.
1.2 Project Objectives
The research presented in this report is part of Partnered Pavement Research Center Strategic Plan
Element 4.18 ( PPRC SPE 4.18), titled “ Warm- Mix Asphalt Study,” undertaken for Caltrans by the
University of California Pavement Research Center ( UCPRC). The objective of this project is to
determine whether the use of additives intended to reduce the production and construction temperatures of
asphalt concrete influence mix production processes, construction procedures, and the short-, medium-,
and/ or long- term performance of hot- mix asphalt. The potential benefits of using the additives will also be
quantified. This is to be achieved through the following tasks:
 Develop a detailed work plan ( 3) for Heavy Vehicle Simulator ( HVS) and laboratory testing
( Completed in September 2007).
2 UCPRC- RR- 2008- 11
 Construct a test track ( subgrade preparation, aggregate base- course, tack coat, and asphalt wearing
course) at the Graniterock A. R. Wilson quarry near Aromas, California, with four sections as
follows ( Completed in September 2007):
1. Conventional dense- graded asphalt concrete ( DGAC) mix. This will serve as the control
section.
2. DGAC warm- mix asphalt with Advera WMA ® additive ( referred to as Advera in this report).
3. DGAC warm- mix asphalt with Evotherm DAT ™ additive ( referred to as Evotherm in this
report).
4. DGAC warm- mix asphalt with Sasobit ® additive ( referred to as Sasobit in the report).
 Identify and demarcate three HVS test sections on each section ( Completed in September 2007).
 Test each section with the HVS in separate phases, with later phases dependent on the outcome of
earlier phases and laboratory tests ( Phase 1 completed in April 2008).
 Carry out a series of laboratory tests to assess rutting and fatigue behavior ( Phase 1 completed in
August 2008).
 Prepare a series of reports describing the research.
 Prepare recommendations for implementation.
If agreed upon by the stakeholders ( Caltrans, Graniterock, warm- mix technology suppliers), the sequence
listed above or a subset of the sequence will be repeated for gap- graded rubberized asphalt concrete
( RHMA- G), and again for open- graded mixes.
Pilot studies with the technology on in- service pavements will also be supported as part of the study.
1.3 Overall Project Organization
This UCPRC project has been planned as a comprehensive study to be carried out in a series of phases,
with later phases dependent on the results of the initial phase. The planned testing phases include ( 3):
Phase 1 compares early rutting potential at elevated temperatures ( pavement temperature of 50° C at
50 mm [ 122° F at 2.0 in]). HVS trafficking would begin approximately 30 days after construction. Cores
and beams sawn from the sections immediately after construction would be subjected to shear, fatigue,
and moisture sensitivity testing in the laboratory. If the warm- mix asphalt concrete mixes perform
differently to the conventional mixes, moisture sensitivity, additional rutting, and fatigue testing with the
HVS would be considered ( Phases 2, 3 and 4).
UCPRC- RR- 2008- 11 3
 Depending on the outcome of laboratory testing for moisture sensitivity, a testing phase, if deemed
necessary, would assess general performance under dry and wet conditions with special emphasis
on moisture sensitivity.
 Depending on the outcome of laboratory testing for rutting, a testing phase, if deemed necessary,
would assess rutting performance on artificially aged test sections at elevated temperatures ( 50° C at
50 mm [ 122° F at 2.0 in.]). The actual process used to artificially age the sections has not been
finalized, but it would probably follow a protocol developed by the Florida Department of
Transport Accelerated Pavement Testing program, which uses a combination of infrared and
ultraviolet radiation.
 Depending on the outcome of the laboratory study for fatigue, a testing phase, if deemed necessary,
would assess fatigue performance at low temperatures ( 15° C at 50 mm [ 59° F at 2.0 in.]).
 Depending on the outcome of the above testing phases and if agreed upon by the stakeholders
( Caltrans, Graniterock, warm- mix technology suppliers), the sequence listed above or a subset of
the sequence would be repeated for gap- graded rubberized asphalt concrete ( RHMA- G), and again
for open- graded mixes.
This test plan is designed to evaluate short-, medium-, and long- term performance of the mixes.
 Short- term performance is defined as failure by rutting of the asphalt- bound materials.
 Medium- term performance is defined as failure caused by moisture and/ or construction- related
issues.
 Long- term performance is defined as failure from fatigue cracking, reflective cracking, or rutting of
the asphalt- bound and/ or unbound pavement layers.
The questions that will be answered during the evaluation include ( 3):
 What is the approximate comparative energy usage during mix preparation? This will be
determined from the asphalt plant records/ observations.
 Can satisfactory density be achieved at lower temperatures? This will be established from
construction monitoring and subsequent laboratory tests.
 What is the optimal temperature range for achieving compaction requirements? This will be
established from construction monitoring and subsequent laboratory tests.
 What are the cost implications? These will be determined with a basic cost analysis.
 Does the use of the additive influence rutting performance of the mix? This will be determined from
Phase 1 HVS and laboratory tests.
4 UCPRC- RR- 2008- 11
 Is the treated mix more susceptible to moisture sensitivity given that the aggregate is heated to
lower temperatures? This will be determined from Phase 1 laboratory tests and possible additional
laboratory and HVS testing.
 Does the use of the additive influence fatigue performance? This will be determined from Phase 1
laboratory tests and potential additional laboratory and HVS testing.
 Does the use of the additive influence the performance of the mix in any other way? This will be
determined from HVS and laboratory tests ( all phases).
 If the experiment is extended to rubberized and open- graded mixes, are the benefits of using the
additives in these mixes the same as for conventional mixes?
1.3.1 Deliverables
Deliverables from the study will include:
 A detailed work plan for the entire study;
 A report detailing construction, first level- data analysis of the Phase 1 HVS testing, first- level data
analysis of the Phase 1 laboratory testing, and preliminary recommendations ( this report);
 Reports detailing the first- level data analyses of subsequent HVS and laboratory testing phases;
 A detailed 2nd level analysis report for the entire study; and
 A summary report for the entire study.
A series of conference and journal papers documenting various components of the study will also be
prepared.
1.4 Structure and Content of this Report
This report presents an overview of the work carried out in Phase 1 to begin meeting the objectives of the
study, and is organized as follows:
 Chapter 2 summarizes the HVS test track location, design, and construction.
 Chapter 3 details the HVS test section layout and HVS test criteria.
 Chapter 4 provides a summary of the Phase 1 HVS test data collected from each test.
 Chapter 5 discusses the Phase 1 laboratory testing on field- mixed, field- compacted ( FMFC)
specimens sampled from the test track.
 Chapter 6 provides conclusions and preliminary recommendations.
UCPRC- RR- 2008- 11 5
1.5 Measurement Units
Although Caltrans has recently returned to the use of U. S. standard measurement units, metric units have
always been used by the UCPRC in the design and layout of HVS test tracks, and for laboratory and field
measurements and data storage. In this report, metric and English units ( provided in parentheses after the
metric units) are provided in general discussion. In keeping with convention, only metric units are used in
HVS and laboratory data analyses and reporting. A conversion table is provided on Page xxi at the
beginning of this report.
1.6 Terminology
The term “ asphalt concrete” is used in this report as a general descriptor for the surfacing on the test track.
The terms “ hot- mix asphalt ( HMA)” and “ warm- mix asphalt ( WMA)” are used as descriptors to
differentiate between the two technologies discussed in this study.
6 UCPRC- RR- 2008- 11
UCPRC- RR- 2008- 11 7
2. TEST TRACK LOCATION, DESIGN, AND CONSTRUCTION
2.1 Experiment Location
The experiment is located on a service road at the Graniterock Company’s A. R. Wilson Quarry near
Aromas, California. Images of the site are shown in Figure 2.1 through Figure 2.4.
Figure 2.1: General location of test track site.
Graniterock AR Wilson
Quarry and AC plant
8 UCPRC- RR- 2008- 11
Figure 2.2: Location of the test track site at the A. R. Wilson Quarry.
Test track site
Quarry operations
AC plant
Quarry pit
Access road
UCPRC- RR- 2008- 11 9
Figure 2.3: Site layout.
Figure 2.4: Site prior to construction.
View to the
north
View to the
south
Test track: 80m x 8m
Shed
Quarry operations access
road ( sealed)
Berm between test and
access road
Slope direction
10 UCPRC- RR- 2008- 11
2.2 Pavement Design
2.2.1 Layer Thickness
Dynamic Cone Penetrometer ( DCP) tests were performed over the length and width of the proposed test
section location prior to construction to obtain an indication of the subgrade thickness and strength.
Results of the centerline measurements are summarized in Table 2.1. The results indicate an irregular
thickness of imported material and overburden over bedrock. DCP penetration to 800 mm ( 32 in.) was
achieved at the southern end of the section, indicating a relatively thick cover over the bedrock. This
decreased comparatively uniformly northwards along the length of the section, with a penetration of only
200 mm at the northern end of the section. The DCP- determined strength of the upper layer of material
was similar at the various points tested along the length of the section.
Table 2.1: Summary of Centerline DCP Survey
Test Location1
( m)
Penetration Depth
( mm)
Penetration Rate in Top 250 mm
( mm/ blow)
10
20
30
40
50
60
70
80
800
680
590
490
380
300
240
200
2.5
2.5
2.7
2.6
2.4
2.4
2.3
2.4
1 Measured from southern end of section.
A sensitivity analysis of potential pavement designs using layer elastic theory models was carried out
using the DCP results obtained during the site investigation and estimates, based on previous experience,
of the moduli of an aggregate base- course and asphalt concrete surfacing. Components of the sensitivity
analysis included the following 24 cells:
 Three asphalt concrete thicknesses ( 100 mm, 125 mm, and 150 mm)
 Three asphalt concrete moduli ( 600 MPa, 1,000 MPa, and 3,000 MPa)
 Two base- course thicknesses ( 300 mm and 450 mm)
 Two base- course moduli ( 150 MPa and 300 MPa)
 One subbase ( existing layer, 250 mm with modulus of 400 MPa)
 One subgrade ( existing bedrock with modulus of > 3,000 MPa).
A test pavement design was selected to maximize the information that would be collected about the
performance of warm- mix asphalt, taking into consideration that a very strong pavement would lengthen
the testing time before results ( and an understanding of the behavior) could be obtained, while a very
weak pavement could fail before any useful data was collected. The pavement design shown in Figure 2.5
was considered appropriate for the study.
UCPRC- RR- 2008- 11 11
Layer: DGAC
Thickness: 2 x 60 mm = 120 mm ( 4.7 in)
Modulus: 1,000 MPa
Layer: Imported Class 2 Aggregate Base- Course
Thickness: 300 mm ( 12 in)
Modulus: 150 MPa
Layer: Existing Subbase
Thickness: 250 mm ( 10 in)
Modulus: 400 MPa
Layer: Bedrock
Thickness: Semi- infinite
Modulus: > 3,000 MPa
Figure 2.5: Pavement structure for warm- mix asphalt test sections.
2.2.2 Mix Design
A standard Graniterock Company mix design that meets specifications for “ Type- A Asphalt Concrete
19 mm Coarse requirements” ( similar to the example shown in Appendix A) was used in this study. This
mix design differs slightly from the example mix designs provided by Caltrans ( example also shown in
Appendix A) that were included in the study work plan ( 3). The Graniterock mix design has been
extensively used on projects in the vicinity of the asphalt plant. Although these mix designs list PG 64- 10
binder, the Valero Asphalt Plant in Benicia, California, from which the binder was sourced, generally only
supplies PG 64- 16. This binder, however, also satisfies the requirements for the PG 64- 10 grading. The
Hveem- type mix design was not adjusted for accommodation of the warm- mix additives. Key parameters
for the mix design are summarized in Table 2.2.
Aggregates
Aggregates for the base and asphalt concrete were sourced from the Graniterock Company’s nearby
A. R Wilson Quarry. This granitic aggregate is classified as a hornblende gabbro of the Cretaceous Age
and is composed of feldspar, quartz, small quantities of mica or hornblende, minor accessory minerals and
lesser amounts of dark ferromagnesium materials. It is quarried from a narrowly exposed mass of plutonic
rock close to the test track. Key aggregate parameters are provided in Table 2.2.
Warm- Mix Additive Application Rates
The warm- mix additive application rates were determined by the additive suppliers and were as follows:
 Advera: 0.25 percent by mass of mix ( equates to 4.8 percent by mass of binder)
 Evotherm: 0.5 percent by mass of binder
 Sasobit: 1.5 percent by mass of binder
12 UCPRC- RR- 2008- 11
Table 2.2: Key Mix Design Parameters
Parameter Wearing Course Base
Target Range Target Range
Grading: 1"
3/ 4"
1/ 2"
3/ 8"
# 4
# 8
# 16
# 30
# 50
# 100
# 200
100
96
84
72
49
36
26
18
11
7
4
-
91- 100
-
66- 78
42- 56
31- 41
-
14- 22
-
-
2- 6
100
93
-
-
51
-
-
17
-
-
6
100
90- 100
-
-
35- 60
-
-
10- 30
-
-
2- 9
Asphalt concrete binder grade
Recommended bitumen content (% by mass of aggregate)
Hveem Stability at recommended bitumen content
Air- void content (%)
Crushed particles (%)
Sand equivalent (%)
Los Angeles Abrasion at 100 repetitions (%)
Los Angeles Abrasion at 500 repetitions (%)
PG 64- 101
5.2
45
4.5
100
72
9
30
-
5.1- 5.4
-
-
-
-
-
-
-
-
-
-
-
≥ 50
-
-
-
-
-
-
-
-
-
-
Plasticity Index
R- Value
Course aggregate durability
Fine aggregate durability
Optimum moisture content (%)
Maximum dry density ( lb/ ft3)
-
-
-
-
-
-
-
-
-
-
-
-
Non- plastic
≥ 80
≥ 65
≥ 50
6.5
145
-
-
-
-
-
-
1 PG 64- 16 binder supplied as PG64- 10 by binder supplier
2.2.3 Production and Construction Temperatures
Based on discussions between Graniterock Company and the warm- mix additive suppliers, the mix
production temperatures were set at 155° C ( 310° F) for the Control mix and 120° C ( 250° F) for the mixes
with additives. Target breakdown compaction temperatures were set at 145° C to 155° C ( 284° F to 310° F)
for the Control mix and 110° C to 120° C ( 230° F to 250° F) for the mixes with additives.
2.3 Test Track Layout
The test track was laid out as shown in Figure 2.6: Test track layout.. All test track measurements,
locations, and chainage discussed in this report are based on this layout.
2.4 Test Track Preparation
A K- Rail concrete barrier ( referred to as a New Jersey Barrier in some states) was installed along both
sides of the demarcated test track to contain the base- course material and to allow for adequate
compaction of the edges of the test track, thereby providing adequate support for the HVS. The existing
surface was bladed to provide a uniform surface for construction of the base- course ( Figure 2.7).
UCPRC- RR- 2008- 11 13
0m ( y= 0) 2m ( y= 2) 4m ( y= 4) 6m ( y= 6) 8m
0m
Evotherm
Control
10m
20m
30m
Shed
40m
50m
60m
70m
Sasobit
Advera
80m 0m ( y= 0) 2m ( y= 2) 4m ( y= 4) 6m ( y= 6) 8m
Figure 2.6: Test track layout.
Figure 2.7: K- rail placement and subgrade/ subbase preparation.
14 UCPRC- RR- 2008- 11
2.5 Base- Course Construction
2.5.1 Equipment
The following equipment was used during the construction of the base- course:
 Caterpillar 140H grader
 Ingersoll Rand SD100- D steel- wheel vibrating roller
 Sakai SW320 steel- wheel vibrating roller
 15,000 L water tanker
 Dump trucks with trailers ( bottom dump)
 John Deere 210 LE skip loader
2.5.2 Construction
The test track base- course was constructed on August 17, 2007. Crushed base- course material ( granitic)
meeting Caltrans Class- 2 aggregate base- course specifications was imported from a nearby quarry
stockpile with a fleet of bottom- dump trucks and trailers. Material was dumped in windrows, spread with
the grader, watered, and compacted ( steel- wheel roller with vibration) in a series of lifts until the desired
300 mm ( 12 in.) thickness was achieved ( Figure 2.8). A total of 23 loads were dumped. Some early
overwatering was observed, which influenced compaction procedures ( Figure 2.9). Thereafter, the water
tanker was more strictly controlled to prevent further occurrences. Dry material was placed over the
affected areas to absorb excess moisture.
Final levels were checked with a rod- and- level survey to ensure that a consistent base- course thickness
had been achieved.
Figure 2.8: Base- course construction.
UCPRC- RR- 2008- 11 15
Figure 2.8: Base- course construction ( continued).
Figure 2.9: Overwatering during base- course construction.
2.5.3 Instrumentation
Instrumentation in the base- course was limited to four moisture sensors ( ESI Gro- PointTM) for monitoring
its moisture contents during the experiment. Given the proximity of the bedrock, Multi- depth
Deflectometers ( MDD) were not considered. Two transverse trenches were excavated into the base- course
at 20 m and 60 m ( 66 ft and 197 ft) respectively along the test track to accommodate the four moisture
sensors ( Figure 2.10). The excavated material was replaced after installation and compacted to the level of
the finished base- course surface.
16 UCPRC- RR- 2008- 11
Figure 2.10: Installation of moisture sensors.
2.5.4 Construction Quality Control
The base- course was inspected on August 22, 2007 after a seven- day dry back period. The surface was
generally acceptable ( Figure 2.11), but some isolated areas of loose material, segregated material,
shearing, and delamination were observed ( Figure 2.12). Some settlement was also noted in the immediate
proximity of the backfilled moisture sensor trenches.
Figure 2.11: Completed base- course showing tightly bound surface.
UCPRC- RR- 2008- 11 17
Loose surface/ raveling
Segregation/ raveling
Figure 2.12: Isolated areas of distress on the base- course.
These localized problems were corrected by spraying the surface with water and then rolling with a
smooth drum roller ( no vibration) to seal it.
After final rolling, density and deflection measurements were taken on the prepared surface to assess
compaction levels, uniformity, and structural integrity. Density was determined with a nuclear density
gauge, while deflection was measured with a Light Weight Deflectometer ( LWD) and Falling Weight
Deflectometer ( FWD). The plans shown in Figure 2.13 were followed for these measurements.
18 UCPRC- RR- 2008- 11
Base- course density measurement plan Base- course deflection measurement plan
Figure 2.13: Base- course density and deflection measurement plan.
Nuclear Density Gauge
The dry density and moisture content of the base- course, determined from nuclear density gauge
measurements, are summarized in Table 2.3 and Table 2.4 and in Figure 2.14 through Figure 2.16.
Measurements are the average of two readings, the first taken with the gauge positioned longitudinally,
and the second with the gauge positioned transversally ( see figure in Table 2.3). Surface measurements
were determined in the backscatter mode. The maximum dry density of the material was approximately
2,380 kg/ m3 ( 145 lb/ ft3) and the optimum moisture content was approximately 6.5 percent.
UCPRC- RR- 2008- 11 19
Table 2.3: Summary of Base- Course Density Measurements after 7- day Dry Back
Location Depth Dry Density ( kg/ m3)* Along Test Track
( mm) 5 m 10 m 20 m 30 m 40 m 50 m 60 m 70 m 75 m
y= 2 Surface
50
100
150
200
2,318
2,325
2,310
2,313
2,311
2,273
-
-
-
-
2,318
-
-
-
-
2,349
-
-
-
-
2,428
2,377
2,376
2,268
2,443
2,386
-
-
-
-
2,192
-
-
-
-
2,369
-
-
-
-
2,155
2,260
2,268
2,288
2,336
y= 4 Surface
50
100
150
200
2,217
2,289
2,288
2,303
2,291
2,308
-
--
--
--
2,232
-
-
-
-
2,420
-
-
-
-
2,371
2,294
2,375
2,354
2,373
2,322
-
-
-
-
2,294
-
-
-
-
2,390
-
-
-
--
2,276
2,300
2,299
2,345
2,378
y= 6 Surface
50
100
150
200
2,346
2,287
2,294
2,328
2,348
2,262
-
-
-
-
2,165
-
-
-
-
2,371
-
-
-
-
2,289
2,289
2,323
2,396
2,383
2,225
-
-
-
-
2,174
-
-
-
-
2,295
-
-
-
-
2,289
2,275
2,292
2,355
2,336
* Measurements are an average of two measurements taken from two gauge positions
( orientations), A and B, as shown in figure.
Table 2.4: Summary of Base- Course Moisture Content Measurements after 7- day Dry Back
Location Depth Moisture Content (%)
( mm) 5 m 40 m 75 m
y= 2 50
100
150
200
4.2
4.4
4.2
4.4
4.2
4.3
4.1
4.5
4.6
4.7
4.5
4.3
y= 4 50
100
150
200
4.9
5.2
5.0
4.8
5.7
5.4
5.5
5.4
6.3
6.2
6.1
6.1
y= 6 50
100
150
200
4.3
4.2
4.4
4.2
4.3
4.1
4.1
3.9
4.3
4.2
4.0
4.3
y
B
A
20 UCPRC- RR- 2008- 11
2000
2050
2100
2150
2200
2250
2300
2350
2400
2450
5 10 20 30 40 50 60 70 75
Chainage ( m)
Dry Density ( kg/ m3)
y= 2 y= 4 y= 6
Figure 2.14: Summary of average dry density ( backscatter).
2150
2200
2250
2300
2350
2400
2450
2500
5 40 75
Chainage ( m)
Dry Density ( kg/ m3)
y= 2 50mm y= 2 100mm y= 2 150mm y= 2 200mm
y= 4 50mm y= 4 100mm y= 4 150mm y= 4 200mm
y= 6 50mm y= 6 100mm y= 6 150mm y= 6 200mm
Figure 2.15: Summary of average dry density at various depths ( probe).
UCPRC- RR- 2008- 11 21
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
5 40 75
Chainage ( m)
Moisture Content (%)
y= 2 50mm y= 2 100mm y= 2 150mm y= 2 200mm
y= 4 50mm y= 4 100mm y= 4 150mm y= 4 200mm
y= 6 50mm y= 6 100mm y= 6 150mm y= 6 200mm
y= 2 y= 4 y= 6 y= 2 y= 4 y= 6 y= 2 y= 4 y= 6
Figure 2.16: Summary of moisture content at different depths ( probe).
The following observations were made:
 Dry density measured on the surface showed some variation along the length of the section. The
average density measured was 2,297 kg/ m3 or 97 percent of the maximum dry density relative to
California Test Method 216 ( standard deviation of 77 kg/ m3 [ 143 lb/ ft3 and 5 lb/ ft3]). The Caltrans
specification requires 95 percent relative density measured as wet density.
 The dry density increased with increasing depth. This was attributed to the construction method
followed ( compaction of multiple thin lifts). The average densities for the four depths were:
- 50 mm ( 2 in.): 2,299 kg/ m3 ( standard deviation of 34 kg/ m3 [ 143.5 lb/ ft3, SD 2.1 lb/ ft3])
- 100 mm ( 4 in.): 2,314 kg/ m3 ( standard deviation of 38 kg/ m3 [ 144.5 lb/ ft3, SD 2.4 lb/ ft3])
- 150 mm ( 6 in.): 2,328 kg/ m3 ( standard deviation of 39 kg/ m3 [ 145.3 lb/ ft3, SD 2.4 lb/ ft3])
- 200 mm ( 8 in.): 2,355 kg/ m3 ( standard deviation of 45 kg/ m3 [ 147.0 lb/ ft3, SD 2.8 lb/ ft3])
 Some variation in density was evident along the length and width of the section.
 The moisture content measured at three locations immediately after construction ( sampled from the
trenches excavated for the moisture sensors) varied between 7.0 percent and 10.8 percent, with
moisture content increasing with increasing depth. Some areas were considerably above the
optimum moisture content of the material, which was attributed to the overwatering in the early
stages of construction.
 Considerable drying occurred in the seven- day period between construction and measurements with
the nuclear gauge. The average gauge- determined moisture content was 4.7 percent ( standard
deviation of 0.7 percent). The lowest recording was 3.9 percent and the highest was 6.3 percent.
22 UCPRC- RR- 2008- 11
Light Weight Deflectometer
Measurements were taken at 1.0 m intervals ( start point at 5.0 m and end point at 75 m in Figure 2.13)
along the centerline of each section ( i. e., y = 2 m and y = 6.0 m in Figure 2.13) and at 5.0 m intervals
along the centerline of the test track ( i. e., y = 4.0 m). Only one set of measurements was taken as the base
material was not expected to be temperature sensitive. Average results of the 6.0 kN load drop are
summarized in Table 2.5 and Figure 2.17 and Figure 2.18. There was some difference in the deflections
measured in the base- course on the four sections, as well as some variation along the length of each
section. This was attributed to overwatering during construction, which probably resulted in inconsistent
drying of the base- course material. Deflections on the Control and Evotherm sections were higher than
those recorded on the Advera and Sasobit sections. This was attributed to slower drying of the former two
sections due to shading by the shed for a portion of each day. Deflections in the subgrade were very small
and consistent, as expected, due to the proximity of the bedrock.
Table 2.5: Summary of Base- Course LWD Measurements
Deflection @ D11
( micron)
Deflection @ D2
( micron)
Deflection @ D3
( micron)
Section
AM PM AM PM AM PM
Control
Advera
Evotherm
Sasobit
184.0
71.6
135.7
91.7
-
-
-
-
19.5
12.0
15.4
18.1
-
-
-
-
9.6
6.8
9.7
9.7
-
-
-
-
Average
Std deviation ( mm)
CoV2 (%)
120.7
50.0
41.4
-
-
-
16.2
3.3
20.4
-
-
-
8.9
1.4
16.0
-
-
-
1 Geophone D1, offset 0mm
2 CoV: Coefficient of variance
Geophone D2, offset 300mm Geophone D3, offset 600mm
0
20
40
60
80
100
120
140
160
180
200
Control Advera Evotherm Sasobit
Deflection ( micron)
D1 - AM D2 - AM D3 - AM
Figure 2.17: Summary of average LWD deflection by section.
UCPRC- RR- 2008- 11 23
0
50
100
150
200
250
0 10 20 30 40 50 60 70 80
Chainage ( m)
Deflection under 6kN Load ( micron)
Line 2m Line 4m Line 6m
Figure 2.18: Summary of LWD base- course deflection measurements ( D1 geophone).
Falling Weight Deflectometer
FWD measurements were taken at the same positions as those taken with the LWD. Only one set of
measurements was taken. Average results of the second 40 kN load drop are summarized in Table 2.6 and
in Figure 2.19 through Figure 2.21. Similar trends to those of the LWD measurements were observed with
similar variation along the length of each section. Higher deflections were again noted on the Control and
Evotherm sections. Deflections in the out sensors, which are influenced by the subgrade, were also very
small and consistent due to the presence of bedrock.
Table 2.6: Summary of FWD Measurements on the Base- Course
Deflection @ D11
( mm)
Deflection @ D62
( mm)
Deflection @ D33
( mm)
Deflection @ D54
( mm)
Section
AM PM AM PM AM PM AM PM
Control
Advera
Evotherm
Sasobit
0.666
0.552
0.390
0.479
-
-
-
-
0.053
0.056
0.043
0.061
-
-
-
-
0.201
0.152
0.101
0.167
-
-
-
-
0.078
0.075
0.055
0.087
-
-
-
-
Average
Std deviation ( mm)
CoV (%)
0.522
0.117
22
-
-
-
0.053
0.007
0.140
-
-
-
0.155
0.042
0.268
-
-
-
0.074
0.013
0.181
-
-
-
Average Temperatures
AM (° C) PM (° C) AM (° F) PM (° F)
Section
Air Surface Air Surface Air Surface Air Surface
Control
Advera 16.4 19.8 - - 61 34 - -
Evotherm
Sasobit 15.2 18.4 - - 59 65 - -
1 Geophone D1, 0 mm offset
3 Geophone D3, 315 mm offset
2 Geophone D6, 925 mm offset
4 Geophone D5, 630 mm offset
24 UCPRC- RR- 2008- 11
0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.700
D1 - AM D3 - AM D5 - AM D6 - AM
Deflection ( mm)
Control Evotherm Advera Sasobit
Figure 2.19: Summary of average FWD deflection by section.
0
0.2
0.4
0.6
0.8
1
1.2
0 10 20 30 40 50 60 70 80
Chainage ( m)
Surface Deflection under 40kN Load ( mm)
D1 along Y= 2m D1 along Y= 6m D1 along Y= 4m
Figure 2.20: Summary of FWD base- course deflection measurements ( D1 geophone).
UCPRC- RR- 2008- 11 25
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0 10 20 30 40 50 60 70 80
Chainage ( m)
Surface Deflection under 40kN Load ( mm)
D6 along Y= 2m D6 along Y= 6m D6 along Y= 4m
Figure 2.21: Summary of FWD subgrade deflection measurements ( D6 geophone).
2.6 Asphalt Concrete Production
Technical representatives from each of the additive suppliers were on site before and during mix
production, and worked with Graniterock Company staff to modify the plant and monitor mix production
with their additives.
2.6.1 Plant Modifications
Modifications were made to the asphalt binder feedline on the asphalt plant to accommodate the addition
of the Advera and Evotherm additives ( Figure 2.22). Customized, calibrated additive delivery systems
were provided by the two manufacturers ( Figure 2.23 and Figure 2.24), who oversaw all necessary
installations. It was originally intended that the Sasobit be blended at the refinery and delivered with the
binder. However, the refinery could not complete the terminal blend and the additive was instead added to
the binder tanker on site prior to mix production ( Figure 2.25). The tanker was later connected directly to
the asphalt plant feedline. The asphalt binder, sourced from the Valero Asphalt Plant in Benicia,
California, was delivered on the day of production.
2.6.2 Mix Production
Asphalt production started at 07: 40 AM on August 24, 2007. Production began with the Control mix,
followed by the Advera, Evotherm, and Sasobit mixes ( i. e., alphabetical order). Approximately 150 tonnes
of each mix were produced and then stored in insulated silos. The first approximately 20 tonnes of each
mix was “ wasted” to ensure that a consistent mix was used on the test track. This material was used to
26 UCPRC- RR- 2008- 11
pave a parking area close to the test track, providing the paving crew with an opportunity to familiarize
themselves with each mix.
Figure 2.22: Plant modifications for admixtures. Figure 2.23: Advera supply system.
Figure 2.24: Evotherm supply system. Figure 2.25: Sasobit mixing.
Initial planning required that production of all four mixes be completed before construction was started.
However, problems with the feedline from the tanker with Sasobit binder during the production run with
that additive required a halting of mix production to correct the problem, empty the silo, mix Sasobit in a
new binder tanker, and then restart mix production. Consequently, paving of the parking areas with the
“ wasted” material started prior to completion of the second Sasobit mix production run to allow sufficient
time for all paving to be completed and to use the discarded initial mix.
Although considered in the work plan, plant emissions were not monitored due to the small volume of
each mix produced.
Evotherm feed
Advera feed
Asphalt feed
Advera supply system
UCPRC- RR- 2008- 11 27
A summary of the mix production observations is provided in Table 2.7. Actual mix production
temperatures were at or close to the planned temperatures. The mix rates of the Evotherm and Sasobit
were as planned ( monitored by additive suppliers). The Advera was added at a slightly lower rate than
planned due to a feed- rate problem on their equipment. However, the rate was still within the range
usually used for the additive.
Table 2.7: Summary of Mix Production Observations
Mix Start Time End Time Mix
Temperature
(° C [° F])
Baghouse
Temperature
(° C [° F])
Production
Rate
( tonnes/ hour)
Control
Advera
Evotherm
Sasobit 1*
Sasobit 2
07: 45
08: 20
08: 47
09: 15
12: 25
08: 00
08: 35
09: 12
09: 26
12: 45
153 ( 308)
120 ( 248)
122 ( 252)
121 ( 251)
120 ( 248)
118 ( 245)
118 ( 245)
116 ( 240)
116 ( 240)
112 ( 235)
254
268
256
252
244
* Sasobit 1 mix rejected due to binder feed problems
Additive Application Rates
(% by mass of binder)
Mix Target Actual
Control
Advera
Evotherm
Sasobit
-
4.8
0.5
1.5
-
4.45
0.5
1.5
2.6.3 Quality Control
Asphalt Binder
A certificate of compliance was provided by the binder supplier with the delivery. A copy of this
certificate is provided in Appendix B.
Performance- grade testing of the asphalt binder was undertaken by the Mobile Asphalt Binder Testing
Laboratory ( MABTL) Program within the Federal Highway Administration ( FHWA) Office of Pavement
Technology. Testing followed the AASHTO M- 320 Table 1 ( M- 320) and AASHTO M- 320 Table 2
( M320- T2) requirements. The M320- Continuous grading is based on the Table 1 testing requirements.
Tests were undertaken on the base binder, on laboratory- blended base binder plus warm- mix additives,
and on field- blended base binder plus Sasobit. Field- blended samples of the binder with Advera and
Evotherm could not be collected due to the nature of the asphalt plant modifications. Samples of the
binder and warm- mix additives were collected at the asphalt plant on the day of production and then
shipped to the MABTL in five- liter metal paint can style containers with friction lids. These containers
were heated in order to further split the material into one- liter containers. The warm- mix additives were
blended in the laboratory using a low shear mixer and heating mantel at the same rates as those used on
the day of production. The binder was heated to 138° C for a minimum time to allow the binder to be fluid
enough to blend the WMA technology with the base binder in the low shear mixer.
28 UCPRC- RR- 2008- 11
Key results of the binder testing are listed in Table 2.8. Test results were considered by the FHWA as
acceptable. The base binder was graded as PG 64- 22, slightly better ( in terms of low- temperature
cracking) than the performance grade of PG 64- 16 specified in the work plan and shown on the supplier’s
certificate of compliance. The addition of Advera and Sasobit changed the performance grading from
PG 64- 22 to PG 70- 22 and increased the critical cracking temperature by approximately 1.0° C, implying
both have much better high- temperature rutting performance, but slightly worse ( 1.0° C and 0.9° C
respectively) low- temperature cracking performance than the base binder. The addition of Evotherm did
not alter the performance grading of the base binder.
An increase in the high temperature grade PG 64 to PG 70 due to the addition of Sasobit was expected due
to the stiffening effect of the wax additive. A change in the high and low temperature grade achieved with
the addition of Sasobit is dependant on the specific base binder. The increase in the high temperature
grade due to the addition of the Advera was not expected based on the zeolite’s material properties and
previous FHWA testing experience with Advera modified binders; which typically do not significantly
impact the performance grade. As shown in the M320- Continuous data column in Table 2.8, both the
Base- plus- Advera and the Base- plus- Evotherm high temperature performance grades were borderline on
the 70° C cutoff between a PG 64 and PG 70 designation. The Base- plus- Advera high temperature
continuous performance grade exceeded the 70° C limit by 0.2° C while the Base- plus- Evotherm
continuous grade was below the cutoff by 0.6° C. The difference in high temperature performance grade is
an effect of having the test results for this specific binder closely border this 70° C temperature. This
borderline difference in the Advera and Evotherm technologies with respect to the 70° C limiting value is
due to various factors including the reheating of the base binder in the laboratory for splitting and
blending, the inherent variability in the test procedures, the ageing criteria specified in the test procedures,
and the base binder’s sensitivity to ageing. An additional Base- plus- Advera sample was tested and graded
in the laboratory to confirm the test results. The original test results were confirmed, although one
additional re- heating cycle was required which further increased the M320 continuous grade temperatures.
Table 2.8: Summary of Binder Performance- Grade Test Results
Asphalt Binder M320 M320- T2 M320- Continuous Critical Crack Temp.
(° C)
Base
Base + Advera
Base + Evotherm
Base + Sasobit ( lab)
Base + Sasobit ( field)
PG 64- 22
PG 70- 22
PG 64- 22
PG 70- 22
PG 70- 22
PG 64- 22
PG 70- 22
PG 64- 22
PG 70- 22
PG 70- 22
67.0- 26.7
70.2- 26.0
69.4- 26.8
72.8- 26.0
71.7- 24.2
- 24.0
- 23.0
- 23.9
- 23.1
- 22.0
Asphalt Mix
The actual mix design properties were not assessed by Caltrans since numerous tests have been
undertaken in the past on the mix design used.
UCPRC- RR- 2008- 11 29
Quality control of the mixes produced for the test track was undertaken by Graniterock Company on mix
sampled from the trucks at the silos. Hveem tests and kneading compaction were not used for this testing
because no research or protocols are available for determining a kneading compaction temperature for
warm- mix asphalt. Graniterock instead undertook Marshall and Superpave Gyratory compaction and
Marshall Stability tests to compare the four mixes. The results are summarized in Table 2.9.
Table 2.9: Quality Control of Mix After Production
Parameter Target Range Control Advera Evotherm Sasobit
Grading
1"
3/ 4"
1/ 2"
3/ 8"
# 4
# 8
# 16
# 30
# 50
# 100
# 200
100
96
84
72
49
36
26
18
11
7
4
-
91- 100
-
66- 78
42- 56
31- 41
-
14- 22
-
-
2- 6
100.0
96.0
85.2
72.8
48.0
36.0
25.3
17.8
11.2
6.4
3.7
100.0
95.8
86.0
74.9
51.7
39.9
28.0
19.2
11.4
6.7
4.2
100.0
97.3
88.2
75.9
50.2
39.4
28.2
19.3
11.3
6.6
4.1
100.0
96.5
86.2
75.1
50.5
38.1
26.3
17.9
10.7
6.1
3.8
AC Binder Content (%) 1 5.2 5.1 - 5.4 5.29 5.14 5.23 4.48
Max. Specific Gravity2 - - 2.567 2.581 2.596 2.606
Marshall Compaction3
Compaction Temperature (° C)
Blows per face
Bulk Specific Gravity
Air- void Content (%)
-
-
-
-
-
-
-
-
139
75
2.511
2.18
115
75
2.474
4.15
112
75
2.493
3.97
124
75
2.464
5.45
Gyratory Compaction3
Compaction Temperature (° C)
Number of Gyrations
Bulk Specific Gravity
Air- void Content (%)
-
-
-
-
-
-
-
-
139
100
2.526
1.60
115
100
2.522
2.29
112
100
2.528
2.62
124
100
2.510
3.68
Marshall Stability ( lbs) 4
Marshall Flow ( 0.01 in.)
1,800 min
-
-
-
4,267
11.8
3,030
10.8
3,320
10.2
3,307
12.1
Moisture ( before plant) (%)
Moisture ( after silo) (%)
-
< 1.0
-
-
0.24
0.09
0.41
0.25
0.37
0.32
0.31
0.25
1 AASHTO T- 308 2 AASHTO T- 209 3 AASHTO T- 166 4 AASHTO T- 245
The following observations were made:
 The aggregate gradations of the four mixes were similar, generally met the targets, and were within
the required ranges.
 The binder contents of the Control, Advera, and Evotherm mixes were similar and all close to the
target. The binder content of the Sasobit mix was 0.72 percent below the target and 0.62 percent
below the lowest permissible content. This discrepancy is likely to influence behavior of the mix
and will be taken into consideration in performance discussions in Chapter 4. The problem was
attributed to the asphalt plant operation and binder feed rate from the tanker during mix production.
 The maximum specific gravities of the four mixes were within a relatively close range, but showed
an increase of between 0.010 and 0.015 with each subsequent mix produced.
30 UCPRC- RR- 2008- 11
 The bulk specific gravities of the four mixes, determined from Marshall- compacted specimens,
were within a relatively close range ( difference of 0.047 between highest and lowest). The Control
mix had the highest bulk specific gravity of the four mixes and Sasobit the lowest.
 The air- void contents of the four mixes, determined from Marshall- compacted specimens, were
notably different, with the Control mix having a significantly lower air- void content than the mixes
with additives. The Control mix had the lowest air- void content ( 2.18 percent) and the Sasobit mix
the highest air- void content ( 5.45 percent). It is not clear whether this was a testing inconsistency,
or a result of the warm- mix production process. This will be assessed in the proposed Phase 2
laboratory testing program ( 3). ( Laboratory mix- design testing procedures are also currently being
investigated as part of a National Cooperative Highway Research Project [ NCHRP 9- 43].)
 The bulk specific gravities of the four mixes, determined from gyratory- compacted specimens, were
within a closer range compared to the Marshall- compacted specimens ( difference of 0.018 between
highest and lowest). The Control, Advera, and Evotherm mixes essentially had the same bulk
specific gravity, with the Sasobit mix having a slightly lower value.
 The air- void contents of the four mixes, determined from gyratory- compacted specimens, were also
notably different, with the Control mix again having a significantly lower air- void content than the
mixes with additives. The Control mix had the lowest air- void content ( 1.60 percent) and the
Sasobit mix the highest ( 3.68 percent).
 The Marshall stability of the Control mix was significantly higher than the mixes with additives
( approximately 1,000 lb higher). However, the stabilities of all the mixes were well above the
minimum limit.
 The Marshall flows did not follow similar trends. The Evotherm and Advera mixes had the lowest
Marshall flows ( 10.2 and 10.8 respectively) followed by the Control mix ( 11.8) and the Sasobit mix
( 12.1). The Sasobit mix was expected to have the lowest flow, given that it had the lowest binder
content.
 There was some variability in the moisture contents of the aggregate just prior to it entering the
drum, with the material used in the Control mix having the lowest moisture content ( 0.24 percent)
and that used in the Advera mix the highest moisture content ( 0.41 percent). The moisture contents
of all four aggregate runs prior to entering the drum were still lower than the Caltrans end- of- drum
moisture content specification of 1.0 percent ( 4).
 The moisture contents of the mix samples collected at the silos showed a more interesting trend.
The moisture content of the Control mix was just 0.09 percent, considerably lower than those of the
mixes with additives, which had moisture contents of 0.25 percent ( Advera and Sasobit mixes) and
0.32 percent ( Evotherm mix). Although moisture contents in all mixes were well below the
UCPRC- RR- 2008- 11 31
minimum specified limit, the higher moisture content of the modified mixes indicates that
potentially less moisture evaporates from the aggregate at the lower production temperatures.
2.7 Asphalt Concrete Placement
Asphalt concrete lay- down and compaction were monitored and documented by UCPRC staff. The
proceedings were also observed by Caltrans staff and representatives from Graniterock Company and the
additive suppliers.
2.7.1 Placement
Introduction
Construction started with the ramps to the test track, thereby ensuring easier and more level access for the
paver and compaction equipment. The first “ wasted” tonnage from the Control mix was used for this
application. After completion of the ramps, test strips were constructed in an adjacent parking lot. This
consumed the first “ wasted” tonnage of each mix, as well the rejected first production run of the Sasobit
mix. It also provided an opportunity for the paving crew to familiarize themselves with the warm- mix
asphalt. Initially the test strip was planned to serve as an early- opening experiment under quarry truck
traffic to assess the potential for early rutting immediately after construction. However, this did not
materialize as there was no through- traffic in the area. The test strips and test track sections were
constructed in the same order as asphalt production ( i. e., Control, followed by warm- mix sections in
alphabetical order).
Equipment
The following equipment was used during placement of the asphalt concrete layers.
 Caterpillar 1000D paver
 Sakai SW850 steel- wheel vibrating roller ( breakdown compaction)
 Sakai SW850 steel- wheel vibrating roller ( final rolling)
 Sakai GW750 rubber- tired roller
 Sakai SW320 steel- wheel vibrating roller ( ramps)
 Binder distributor ( tack coat application)
 Dump trucks
 John Deere 1483 skip loader
32 UCPRC- RR- 2008- 11
Prime Coat
After a final visual inspection of the base, the test track was lightly sprayed with water to bind any surface
fines ( Figure 2.26, approximately 7: 55 AM). Once the water had penetrated, prime coat ( SS- 1 asphalt
emulsion) was applied with a hand- held lance over the entire test track ( Figure 2.27, approximately
8: 10 AM to 8: 25 AM). The application rate was estimated at 1.0 L/ m2 ( 0.25 gal/ yd2), but due to the
method of application it could not be accurately determined or controlled. The prime was allowed to break
during the construction of the test strip. Some areas of poor adhesion were noted, and some damage was
caused by foot and vehicular traffic ( Figure 2.28). Weather conditions at the time of priming were as
follows:
 Air temperature: 16° C ( 61° F)
 Surface temperature: 13° C ( 56° F)
 Relative humidity: 83 percent
 Dew point: 13° C ( 55° F)
Figure 2.26: Water spray prior to priming. Figure 2.27: Prime application.
Figure 2.28: Damage to prime by vehicle and foot traffic.
UCPRC- RR- 2008- 11 33
First Lift: Control Section
Placement of the asphalt concrete on the Control section started at 12: 15 PM with the positioning of the
paver at the start of the Control section. The first truck load was tipped into the paver at 12: 25 PM. Three
loads were used and the paver reached the end of the section eight minutes after starting. Some haze was
noted during tipping. Breakdown rolling started as soon as the paver was moved off of the section.
Density and temperature measurements were taken throughout ( see Section 0). Six passes were made with
the breakdown roller ( approximately six minutes). This was followed by the rubber- tired roller, which
applied ten passes in an 11- minute period. Final rolling was completed with the steel- wheel roller ( with
vibration) in three passes at 12: 57 PM. Paver spillage was removed from the end of the section to ensure a
clean and regular surface and join for the Advera section. The second part of the final rolling with the
steel- wheel roller ( three passes, no vibration) was completed when the section had cooled. This took place
between 1: 45 PM and 1: 50 PM. The construction process is illustrated in Figure 2.29.
Mix delivery ( note haze) Paver train
Breakdown rolling Density check
Figure 2.29: Control: Placement of first lift of asphalt concrete.
Haze
34 UCPRC- RR- 2008- 11
Rubber- tired roller Final rolling
Figure 2.29: Control: Placement of first lift of asphalt concrete ( continued).
No problems were noted during breakdown rolling, however, some pick- up was observed during rolling
with the rubber- tired roller ( Figure 2.30). This was corrected during the final roll.
Figure 2.30: Control: Pick up during rubber- tire rolling.
First Lift: Advera Section
The same process described above was followed for the placement of the Advera mix, which started at
1: 12 PM. No haze was observed during tipping of the mix into the paver ( Figure 2.31). Breakdown rolling
was achieved with eight passes. Ten passes were made with the rubber- tired roller followed by four passes
for initial final rolling ( with vibration). This phase of construction was completed at 1: 38 PM
( 33 minutes). The second part of the final rolling ( three passes, no vibration) was completed between
1: 45 PM and 1: 50 PM at the same time as the Control. No problems were observed during any of the
compaction phases and a tightly bound surface was achieved ( Figure 2.32).
UCPRC- RR- 2008- 11 35
Figure 2.31: Advera: Mix delivery, no haze. Figure 2.32: Advera: Surface after final rolling.
First Lift: Evotherm Section
The same process followed for the previous two sections was also followed for the Evotherm mix.
Construction started at 1: 50 PM. No haze was observed during tipping of the mix into the paver. A rag
was accidentally dropped in the paver, leaving an indentation on the mat that was repaired by hand
( Figure 2.33 and Figure 2.34). Six passes were made with the breakdown roller and twelve with the
rubber- tired roller. Initial final rolling was achieved in four passes ( with vibration). This phase of
construction was completed at 2: 15 PM and took 25 minutes. The second part of the final rolling ( three
passes, no vibration) was completed between 2: 45 PM and 2: 50 PM. No problems were observed during
the breakdown rolling, but some shearing was noted under the rubber- tired roller ( Figure 2.35). Final
rolling provided a smooth, tightly bound surface ( Figure 2.36).
Figure 2.33: Evotherm: Damage behind paver. Figure 2.34: Evotherm: Damage repair.
36 UCPRC- RR- 2008- 11
Figure 2.35: Evotherm: Shear after rubber-tired
roller.
Figure 2.36: Evotherm: Surface after final
rolling.
First Lift: Sasobit Section
The same process followed for the previous three sections was also followed for the Sasobit mix.
Construction started at 2: 17 PM. No haze was observed during tipping of the mix into the paver. Seven
passes were made with the breakdown roller, during which the mix appeared tender, with some shearing
noted ( Figure 2.37). This was attributed in part to higher temperatures on this section ( probably due to the
shorter period between mix production and placement) compared to the Advera and Evotherm sections.
Twelve passes were completed with the rubber- tired roller, during which some pick- up was also observed
( Figure 2.38). Initial final rolling was achieved in four passes ( with vibration), with tenderness still
evident in the form of shearing ( Figure 2.39). This phase of construction was completed at 2: 42 PM
( 25 minutes). The second part of the final rolling ( five passes, no vibration) was completed between
3: 00 PM and 3: 05 PM, after which a smooth and relatively tightly bound surface was achieved
( Figure 2.40).
Figure 2.37: Sasobit: Shearing during
breakdown rolling.
Figure 2.38: Sasobit: Pick up during rubber-tire
rolling.
UCPRC- RR- 2008- 11 37
Figure 2.39: Sasobit: Surface after final rolling. Figure 2.40: Sasobit: Shearing during final
rolling.
Tack Coat Between Lifts
Tack coat was applied in two separate passes, the first on the Control and Advera sections at 3: 00 PM
( Figure 2.41), and the second on the Evotherm and Sasobit sections at 3: 50 PM. An SS- 1 emulsion was
applied with a distributor at an application rate of approximately 0.5 L/ m2 ( 0.1 gal/ yd2). Some steam was
observed when applying over the Sasobit section ( Figure 2.42), probably due to the shorter cooling time
since the placement of the first lift compared to the other sections.
Figure 2.41: Tack coat application ( Control). Figure 2.42: Tack coat application ( Sasobit).
Second Lift: Control Section
The same placement and compaction process was followed for the second lift of the Control mix, which
started at 3: 03 PM, with the section completely shaded by the adjacent shed. Some haze was again
observed during tipping of the mix into the paver. Breakdown rolling was achieved with six passes, with
some tenderness observed. Twelve passes were made with the rubber- tired roller followed by three passes
for the first phase of final rolling ( with vibration). This phase of construction was completed at 3: 26 PM
38 UCPRC- RR- 2008- 11
( 23 minutes). The second part of the final rolling ( three passes, no vibration) was completed between
4: 08 PM and 4: 12 PM. No problems were observed during rubber- tired and final rolling.
Second Lift: Advera Section
The same placement and compaction process was followed for the second lift of the Advera mix, which
started at 3: 28 PM. No haze was observed during tipping of the mix into the paver. Breakdown rolling was
achieved with eight passes, followed by twelve passes with the rubber- tired roller and three passes with
the steel- wheel roller for the first phase of final rolling ( with vibration). This phase of construction was
completed at 3: 47 PM ( 19 minutes). The second part of the final rolling ( three passes, no vibration) was
completed between 4: 08 PM and 4: 12 PM at the same time as final rolling on the Control section. The
layer appeared very stable during all stages of compaction and no tenderness or shearing was observed.
Second Lift: Evotherm Section
The same placement and compaction process was followed for the second lift of the Evotherm mix, which
started at 3: 48 PM. The section was shaded by the adjacent shed for the duration of work. No haze was
observed during tipping of the mix into the paver. Breakdown rolling was achieved with six passes,
followed by twelve passes with the rubber- tired roller and three passes with the steel- wheel roller for the
first phase of final rolling ( with vibration). This phase of construction was completed at 4: 20 PM
( 30 minutes). The second part of the final rolling ( three passes, no vibration) was completed between
5: 00 PM and 5: 12 PM. Some tenderness was observed during the breakdown rolling and rolling with the
rubber- tired roller. No problems were observed during final rolling.
Second Lift: Sasobit Section
The same placement and compaction process was followed for the second lift of the Sasobit mix, which
started at 4: 20 PM. No haze was observed during tipping of the mix into the paver. Breakdown rolling was
achieved with six passes. Some tenderness was noted, similar to that observed during compaction of the
first lift. Twelve passes with the rubber- tired roller were applied in the next stage of compaction, with
pick- up again noted. The first phase of final rolling totalled six passes ( with vibration), during which the
layer appeared more stable. This phase of construction was completed at 4: 40 PM ( 30 minutes). The
second part of final rolling ( three passes, no vibration) was completed between 5: 00 PM and 5: 12 PM at
the same time as final rolling on the Evotherm section.
2.7.2 Instrumentation
Two strain gauges were placed on top of the primed base on each section. One gauge ( Tokyo- Sokki
KM- 100HAS) was placed in the transverse position, with the midpoint 1,800 mm ( 70.9 in.) from the
UCPRC- RR- 2008- 11 39
outside edge ( K- rail) of the pavement. The second gauge ( CTL ASG- 152) was placed in the longitudinal
position, with the midpoint 2,000 mm ( 78.7 in.) from the outside edge of the pavement ( Figure 2.43).
Actual positions on each section together with the gauge identifier are listed in Table 2.10.
Table 2.10: Strain Gauge Position Detail
Section Gauge Position*
( m) CTL Label Tokyo Sokki Label
Control
Advera
Evotherm
Sasobit
29.82
69.25
30.96
70.50
R- 45
R- 46
R- 47
R- 48
EKZ 04392
EKZ 04393
EKZ 04394
EKZ 04395
* Measured from x – y = 0 position on southern end of the section ( see Figure 2.6).
Figure 2.43: Strain gauge layout.
Asphalt concrete was removed from the first truck of each mix with a shovel and placed over the strain
gauges and wires to prevent damage by the trucks and the paver ( Figure 2.44).
Figure 2.44: Strain gauge covered with mix.
2.7.3 Quality Control
Quality control, both during and after construction, was undertaken jointly by Graniterock Company and
the UCPRC. This included:
40 UCPRC- RR- 2008- 11
 Placement and compaction temperatures
 Thickness
 Density
 Deflection
 Skid resistance
Placement and Compaction Temperatures
Temperatures were systematically measured throughout the placement of the asphalt concrete using
infrared temperature guns, thermocouples, and an infrared camera. Measurements included:
 Temperature of the mix as it was tipped into the paver
 Temperature of the mix behind the paver
 Temperature of the mat before compaction
 Temperature of the surface during compaction
 Temperature after priming
 Temperature of the surface prior to placing the second lift
 Temperature at the above locations during the second lift
A summary of the measurements is provided in Table 2.11 and in Figure 2.45 and Figure 2.46. The
following observations were made:
 Average temperatures of the Control mix measured in the trucks as it was tipped into the paver were
about 10° C ( 18° F) below the target compaction temperature. This was attributed to cooling in the
silo ( placing of the first lift of the Control mix started approximately four hours after mix
production) and during transport from the asphalt plant. The temperature was, however, still within
Caltrans- specified limits ( 4). The temperature of the Advera mix was within the target for the first
lift, but slightly below the target for the second lift. The temperature of the Evotherm mix was the
same for both lifts, but slightly below the target, while the Sasobit mix was slightly above the target
for the first lift and within the target range for the second lift. The Sasobit mix had the shortest wait
in the silo ( approximately two hours).
 There was very little temperature difference between the material being tipped into the paver and
the mat behind the paver before compaction. The Advera, Evotherm, and Sasobit mixes lost less
heat than the Control mix.
 Temperatures on the Control section dropped by 13° C and 18° C ( 23° F and 32° F) on the first and
second lift respectively between placement with the paver and start of compaction with the
breakdown roller. The drop on the Advera and Sasobit sections was 9° C and 12° C ( 16° F and 22° F)
for the two lifts, while the drop on the Evotherm section was 13° C and 16° C ( 23° F and 29° F).
UCPRC- RR- 2008- 11 41
Table 2.11: Summary of Temperature Measurements
Lift Measuring Point Temperature (° C)
Control Advera Evotherm Sasobit
1st Truck
Paver
Mat
Surface: begin compaction
Surface: average during compaction
Surface: end of compaction
Mid- depth: average during compaction
137
135
135
122
106
94
113
112
110
105
96
81
72
94
107
106
106
93
90
76
92
121
120
117
108
91
74
87
Surface before prime
Surface after prime
Surface before second lift
50
51
50
-
-
53
-
-
51
-
-
54
2nd
Truck
Paver
Mat
Surface: begin compaction
Surface: average during compaction
Surface: end of compaction
Mid- depth: average during compaction
134
128
127
109
93
68
122
109
109
109
97
82
73
100
107
107
107
91
80
72
105
115
113
113
101
84
74
91
Lift Measuring Point Temperature (° F)
Control Advera Evotherm Sasobit
1st Truck
Paver
Mat
Surface: begin compaction
Surface: average during compaction
Surface: end of compaction
Mid depth: average during compaction
279
275
275
252
223
201
235
234
230
221
205
178
162
201
225
223
223
199
194
169
198
250
248
243
226
196
165
189
Surface before prime
Surface after prime
Surface before second lift
122
124
122
-
-
127
-
-
124
-
-
129
2nd
Truck
Paver
Mat
Surface: begin compaction
Surface: average during compaction
Surface: end compaction
Mid- depth: average during compaction
273
262
261
228
199
154
252
228
228
228
207
180
163
212
226
226
226
196
176
162
221
239
235
235
214
183
165
196
 The average temperature difference between the start of breakdown compaction and final rolling on
the Control section was 28° C ( 50° F) for the first lift and 41° C ( 74° F) for the second lift. The
difference for the Advera section was 24° C ( 43° F) for both lifts. On the Evotherm section, the
difference was 17° C and 19° C ( 31° F and 34° F) respectively, and on the Sasobit section the
difference was 34° C and 27° C ( 61° F and 49° F) respectively.
 Average start- and end- compaction temperatures on the Control section were within the Caltrans
specification limits ( 4). The average start- compaction temperatures on the Advera, Evotherm, and
Sasobit sections were below the specification limits ( as required in the experimental design [ 3]), but
end- of- compaction temperatures were within limits ( 4).
42 UCPRC- RR- 2008- 11
0
20
40
60
80
100
120
140
160
Control Advera Evotherm Sasobit
Temperature ( C)
Mat Surface: begin compaction Surface: average during compaction Surface: end compaction
Figure 2.45: Summary of temperature measurements ( first lift).
0
20
40
60
80
100
120
140
160
Control Advera Evotherm Sasobit
Temperature ( C)
Mat Surface: begin compaction Surface: average during compaction Surface: end compaction
Figure 2.46: Summary of temperature measurements ( second lift).
 The rate of temperature loss between initial placement and completion of compaction on the
Control section was significantly higher than on the warm- mix sections.
 Temperature drop on the Control and Evotherm sections did not appear to be influenced by the
shade during placement of the second lift. The differences between the start and end of compaction
on the shaded sections were less than the differences on the Advera and Sasobit sections, which
were placed and compacted in direct sunlight.
UCPRC- RR- 2008- 11 43
Thermal camera images ( FLIR Systems ThermaCAM PM290, recorded by T. J. Holland of Caltrans) of
the mat behind the paver and after compaction with the rubber- tired roller are shown in Figure 2.47. The
images clearly show the lower temperatures of the warm- mix sections and the uniformity in temperature
over the mat. ( Note that temperature scales on the right side of the photographs differ between images.)
Control: First lift behind paver Control: First lift after rubber- tired roller
Advera: First lift behind paver Advera: First lift after rubber- tired roller
Figure 2.47: Thermal images of test track during construction.
44 UCPRC- RR- 2008- 11
Evotherm: First lift behind paver Evotherm: First lift after rubber- tired roller
Sasobit: First lift behind paver Sasobit: First lift after rubber- tired roller
Control: Second lift behind paver Control: Second lift after rubber- tired roller
Figure 2.47: Thermal images of test track during construction ( continued).
UCPRC- RR- 2008- 11 45
Advera: Second lift behind paver Advera: Second lift after rubber- tired roller
Evotherm: Second lift behind paver Evotherm: Second lift after rubber- tired roller
Sasobit: Second lift behind paver Sasobit: Second lift after rubber- tired roller
Figure 2.47: Thermal images of test track during construction ( continued).
46 UCPRC- RR- 2008- 11
Thickness
Thickness was monitored with probes throughout the construction process. The thickness of the slabs
removed for laboratory testing after construction ( see Section 0) was also measured. The average
thickness of the combined two layers was 112 mm ( 4.4 in.), 8.0 mm ( 0.3 in.) thinner than the design
thickness of 120 mm ( 4.7 in.). The thinnest measurement recorded was 98 mm ( 3.9 in.) and the thickest
124 mm ( 4.9 in.). This range of thicknesses was considered acceptable and representative of typical
construction projects. Actual thicknesses of the asphalt concrete layers adjacent to the HVS test sections
will be determined from cores taken during the planned forensic investigation after all HVS testing has
been completed.
Density
Compaction was monitored using nuclear and non- nuclear gauges throughout the construction process.
The results were used to manage the number of rolling passes, roller selection, and roller settings. These
densities were monitored but not recorded.
Final density measurements were taken on August 26, 2007 by Graniterock Company, using a calibrated
nuclear gauge. Measurements were taken according to the plan shown in Figure 2.48. A summary of the
results is provided in Table 2.12. The results show some variability among the four sections as well as
within each section. Air- void contents determined from these measurements correspond to observations
made during construction ( see Section 2.7). The Control and Advera sections, which appeared to compact
without problems on the day with little or no evidence of tenderness, had the lowest air- void contents ( 5.6
and 5.4 percent respectively). The Evotherm and Sasobit sections, which showed signs of tenderness at
various stages of the compaction process, had higher air- void contents ( 7.1 and 7.0 percent respectively).
Density increased with increasing distance from the outside edge ( i. e., K- rail) on the Advera, Evotherm
and Sasobit sections. Density was highest along the middle of the section for the Control.
Falling Weight Deflectometer
FWD measurements were taken on September 5, 2007 at 1.0 m intervals ( start point 5.0 m and end point
75 m) along the centerline of each section ( i. e., y = 2.0 m and y = 6.0 m) Average results of the second
40 kN load drop are summarized in Table 2.13 and in Figure 2.49 through Figure 2.51. There was no
significant difference in the deflections measured on the four sections and relatively little variation along
the length of each section, indicating consistent construction. Sensor 1 deflections on the asphalt concrete
decreased slightly with increasing chainage ( south to north), consistent with the changing depth of the
bedrock. The Advera section had the lowest average deflections, followed by the Sasobit, Control, and
Evotherm sections. The asphalt concrete layer exhibited some temperature sensitivity, as expected.
UCPRC- RR- 2008- 11 47
Figure 2.48: Asphalt concrete density measurement plan.
Table 2.12: Summary of Asphalt Concrete Density Measurements
Position Nuclear Gauge- Determined Specific Gravity
Control Advera Evotherm Sasobit
1
2
3
4
2.383
2.426
2.398
2.406
2.442
2.422
2.422
2.424
2.393
2.399
2.381
2.417
2.415
2.429
2.424
2.398
Average 1- 4 2.403 2.428 2.398 2.417
5
6
7
2.449
2.457
2.455
2.445
2.447
2.435
2.413
2.390
2.436
2.415
2.428
2.438
Average 5- 7 2.454 2.442 2.413 2.427
8
9
10
2.410
2.419
2.427
2.466
2.448
2.467
2.421
2.443
2.417
2.432
2.433
2.426
Average 8- 10 2.419 2.460 2.427 2.430
Overall average 2.423 2.442 2.411 2.424
Control Advera Evotherm Sasobit
Rice Specific Gravity
In- place air voids (%)
2.567
5.61
2.581
5.39
2.596
7.13
2.606
6.99
48 UCPRC- RR- 2008- 11
Table 2.13: Summary of FWD Measurements
Deflection @ D11
( mm)
Deflection @ D62
( mm)
Deflection @ D33
( mm)
Deflection @ D54
( mm)
Section
AM PM AM PM AM PM AM PM
Control
Advera
Evotherm
Sasobit
0.243
0.186
0.260
0.208
0.360
0.263
0.402
0.322
0.047
0.034
0.045
0.048
0.047
0.038
0.046
0.053
0.149
0.090
0.154
0.125
0.168
0.091
0.162
0.141
0.075
0.045
0.074
0