Rubberized Hot Mix Asphalt Located in Butte County on ... · PDF file1.2 Project Objectives...

California Department of Resources Recycling and Recovery May 15, 2014

Contractor's Report Produced Under Contract By:

Lerose Lane and DingXin Cheng California Pavement Preservation Center

CSU, Chico

Rubberized Hot Mix Asphalt

Located in Butte County on

State Route 99, near Chico

from 0.1 Mile North of Broyles

Road to the Tehama County Line

Disclaimer: This report was produced under contract by the California Pavement Preservation

Center (CP2C), CSU, Chico. The statements and conclusions contained in this report are those of

the contractor and not necessarily those of the Department of Resources Recycling and Recovery

(CalRecycle), its employees, or the State of California and should not be cited or quoted as official

Department policy or direction.

The state makes no warranty, expressed or implied, and assumes no liability for the information

contained in the succeeding text. Any mention of commercial products or processes shall not be

construed as an endorsement of such products or processes.

S T A T E O F C A L I F O R N I A

Edmund G. Brown Jr.

Governor

Matt Rodriquez

Secretary, California Environmental Protection Agency

DEPARTMENT OF RESOURCES RECYCLING AND RECOVERY

Caroll Mortensen

Director

Department of Resources Recycling and Recovery Public Affairs Office

1001 I Street (MS 22-B) P.O. Box 4025

Sacramento, CA 95812-4025 www.calrecycle.ca.gov/Publications/

1-800-RECYCLE (California only) or (916) 341-6300

Publication # DRRR-XXXX-XXX [OPA editor will provide this]

To conserve resources and reduce waste, CalRecycle reports are produced in electronic format only. If printing copies of this document, please consider use of recycled paper containing 100 percent postconsumer

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Copyright © [Year] by the California Department of Resources Recycling and Recovery (CalRecycle). All rights reserved. This publication, or parts thereof, may not be reproduced in any form without permission.

Prepared as part of contract number DRR [11065].

The California Department of Resources Recycling and Recovery (CalRecycle) does not discriminate on the basis of disability in access to its programs. CalRecycle publications are available in accessible formats upon request by calling the Public Affairs Office at (916) 341-6300. Persons with hearing

impairments can reach CalRecycle through the California Relay Service, 1-800-735-2929.

http://www.calrecycle.ca.gov/Publications/

Contractor’s Report i

Table of Contents Table of Contents ........................................................................................................................................... i

List of Figures .............................................................................................................................................. iii

List of Tables ............................................................................................................................................... iv

Executive Summary ...................................................................................................................................... 1

Introduction ............................................................................................................................................ 1

Conclusion .............................................................................................................................................. 1

Recommendations .................................................................................................................................. 1

1 Introduction ................................................................................................................................................ 3

1.1 Background ...................................................................................................................................... 3

1.2 Project Objectives ............................................................................................................................. 4

1.3 Project Scope .................................................................................................................................... 5

2 Pre-construction Data ................................................................................................................................ 5

2.1 Existing Pavement Condition Survey ............................................................................................... 5

2.2 Existing Pavement Structure ............................................................................................................ 6

2.3 Materials and Mix Design ................................................................................................................ 6

3 Construction Process .................................................................................................................................. 8

3.1 Construction Paving Plan ................................................................................................................. 8

3.2 Weather During Construction ........................................................................................................... 8

3.3 Construction Observations ............................................................................................................... 9

3.4 QC Data from Contractor ............................................................................................................... 21

3.5 Testing Data from Caltrans ............................................................................................................ 21

3.6 Emissions and Energy Consumption .............................................................................................. 22

3.7 Problems Encountered .................................................................................................................... 22

4 Post Construction .................................................................................................................................... 23

4.1 Appearance of Finished Mat .......................................................................................................... 23

4.2 Future Plans .................................................................................................................................... 27

5 Findings .................................................................................................................................................. 28

6 Conclusions and Recommendations ....................................................................................................... 30

Abbreviations and Acronyms ..................................................................................................................... 32

Appendix A. Plant Mix #2013, Mix Design Verification by District 3 Materials Laboratory—3/4" HMA

Type A (R10), Dense Graded ..................................................................................................................... 33

Appendix B. Plant Mix #2013 G, Mix Design Verification by District 3 Materials Laboratory—1/2"

RHMA-G .................................................................................................................................................... 43

Appendix C. Asphalt Rubber Binder Formulation .................................................................................... 54

Contractor’s Report ii

Bibliography ............................................................................................................................................... 60

Endnotes ...................................................................................................................................................... 60

Contractor’s Report iii

List of Figures Figure 1 Project Location Map, District 03, Butte and Sutter Counties ........................................................ 3

Figure 2 Caltrans 03-3M5804 Project Limits ................................................................................................. 4

Figure 3 Existing Pavement with Alligator Cracking, and Rutting ................................................................. 5

Figure 4 Binder Storage Tanks for PG 64-16 and Rubberized Binder ......................................................... 7

Figure 5 Aggregate Bins and Cold Feed to Dryer Drum of Aztec Plant ....................................................... 7

Figure 6 Typical Belly Dump ....................................................................................................................... 10

Figure 7 Case Front Loader ........................................................................................................................ 10

Figure 8 Wirtgren Grinder ........................................................................................................................... 11

Figure 9 Self-contained Sweeper ................................................................................................................ 11

Figure 10 Self-contained Sweeper Dumping Grindings .............................................................................. 12

Figure 11 Distribution Truck Used for Emulsion Tack Coat ........................................................................ 12

Figure 12 Cedar Rapids Pick up Machine with Umbrella Lights, Front View ............................................. 13

Figure 13 Cat 20-20B Adjustable Vibratory Screed, Side View .................................................................. 13

Figure 14 Cat 20-20B Adjustable Vibratory Screed, Back View ................................................................. 14

Figure 15 Caterpillar 1000D Paver with Umbrella Lighting, Back View ...................................................... 14

Figure 16 Water Tank ................................................................................................................................. 15

Figure 17 Cat CB 54 Vibratory Rollers ........................................................................................................ 15

Figure 18 Caterpillar PS 150C Rubber Tire Roller ..................................................................................... 16

Figure 19 Caterpillar CB564D Steel Tire Roller .......................................................................................... 16

Figure 20 Paving RHMA-G near PM 44.4 ................................................................................................... 17

Figure 21 RoadTec MTV (shuttle buggy), Front View ................................................................................ 17

Figure 22 RoadTec MTV (shuttle buggy) Transfering Mix to Paver, Side View ......................................... 18

Figure 23 Windrow Temperature in Front of Cedar Rapids Pick Up Machine ............................................ 19

Figure 24 Mat Temperature Directly Behind Screed .................................................................................. 19

Figure 25 Mat Temperature Between 1st and 2

nd Rollers ........................................................................... 20

Figure 26 Mat Temperature Behind 2nd

Roller ............................................................................................ 20

Figure 27 Vibratory Rollers Directly Behind Paver...................................................................................... 21

Figure 28 Grinding on Bridge Deck Prior to Repaving ................................................................................ 22

Figure 29 RHMA-G Finished Mat ................................................................................................................ 23

Contractor’s Report iv

Figure 30 Beginning of Project, Looking North Near Broyles Road ........................................................... 24

Figure 31 Finished Project with Striping and Rumble Strips, Looking North .............................................. 24

Figure 32 Finished Project, with Rumble Strips on Shoulders .................................................................... 25

Figure 33 Rumble Strip on Centerline ......................................................................................................... 25

Figure 34 Finished Project, Looking North .................................................................................................. 26

Figure 35 Pine Creek Bridge near PM 45.5, Looking North ....................................................................... 26

Figure 36 End of Project at Tehama County Line ....................................................................................... 27

Figure 37 RHMA-G Finished Mat on October 2, 2013 ................................................................................ 27

Figure 38 James Cox and Sons, 4-Point Fatigue Testing Apparatus ......................................................... 28

Figure 39 State Route 99 Comparison for Conventional vs. RHMA-G for 4-Point Fatigue Testing ........... 30

List of Tables Table 1 Pavement Structure Thickness Information ..................................................................................... 6

Table 2 Paving Post Mile Limits State Route 99 ........................................................................................... 8

Table 3 Weather Data for August 7-9 and 13, 2013 ..................................................................................... 8

Table 4 HMA and RHMA Temperature Data for August 7-9 and 12-13, 2013 ........................................... 21

Table 5 Asphalt Binder Content and Stability, District 03 for RHMA-G ...................................................... 22

Table 6 State Route 99 Conventional 4-Point Fatigue Testing Results ..................................................... 29

Table 7 State Route 99 RHMA 4-Point Fatigue Testing Results ................................................................ 29

Contractor’s Report v

ACKNOWLEDGMENTS

We appreciate the financial support of CalRecycle for providing the funding for monitoring this

important and meaningful project. We would like to extend our gratitude to Nate Gauff of

CalRecycle, who provided continuous support to this project. We would also appreciate the

support from Caltrans District 03, Resident Engineer, Ben Hargrove, and various George Reed,

Inc. staff including Phil Reader, their Quality Control Manager.

The authors appreciate Gary Hicks of the CP2 Center for his review for both report content and

consistency.

Contractor’s Report 1

Executive Summary

Introduction

This report describes the construction on State Route (SR) 99 near Chico in Butte from Broyles

Road to the Tehama County line. The project includes a rubberized hot mix asphalt gap graded

(RHMA-G) overlay over dense graded hot mix asphalt (HMA). This is an innovative project

using a RHMA-G mix developed by George Reed, Inc. The RHMA-G mix had a high binder

content and was placed during cooler night time temperatures. The purpose of this project was to

maintain pavement on a heavily travelled highway.

The CP2C 's staff collected samples at the plant that were sampled during production. The

samples were tested by the CP2C Laboratory at Langdon Hall on the CSU, Chico campus. To

establish the comparison between the conventional HMA, and the RHMA-G both sets of samples

were prepared and ran on the James Cox and Sons' 4-point bending beam fatigue tester.

Conclusion

The project went down without any significant problems during construction and the District was

pleased with the result. Construction went well and the contractor had good equipment and good

crews. The plant appeared to be producing the RHMA-G mix without problems. The

performance of the project as of October 2013 is good, and it will be monitored over the life of

the treatment by the California Pavement Preservation Center (CP2C). The information on the

project can be found on the CP2C's website: http://www.ecst.csuchico.edu/cp2c/software/pptdb/.

The website includes a database where many of the innovative projects are included for review by

public agencies and contractors.

This project was constructed for a total cost of $650,700. This equates to $17.33 per square yard

for this maintenance project. This RHMA-G appeared to have no visible distresses on March 18,

2014. Overall, the pavement is in very good condition.

The following conclusions can be drawn from this project’s test results:

Rubberized Asphalt Concrete (RAC) does outperform conventional HMA.

o The RHMA laboratory samples sustained more than twice the number of micro

stain cycles before failing.

o The RHMA-G showed superior performance at all micro strain levels.

This performance was documented in lab studies from material samples collected on this

project.

The superior laboratory performance of the RHMA indicates a substantial long term cost

savings. With variability, the cost savings may be around 39%.

Recommendations

An important extension of this study is to document that the field performance of RHMA-G for

this project follows the laboratory performance. To obtain this documentation, it is recommended

that the CP2C continue to monitor this project to determine when distresses start to appear. The

http://www.ecst.csuchico.edu/cp2c/software/pptdb/


distresses that will be monitored are raveling, cracking, and rutting. Once the pavement is

showing distress, the performance of this RHMA-G can be compared to convention mixes, such

as RHMA dense graded mix, and HMAs with unmodified binders in similar climate conditions.


1 Introduction

1.1 Background

This project is best described as a pavement maintenance project which includes resurfacing of

the northbound (NB) and southbound (SB) lanes, including the shoulders, on SR 99 with HMA

and RHMA-G. This is an eco-friendly construction project that uses an average of approximately

1,200 recycled tires per lane mile. The pavement was in poor condition prior to the grinder dig

outs and the overlays. The work on the project was performed during the month of July, 2013,

and was monitored by Lerose Lane from the CP2C. Figure 1 shows the project location in Sutter

and Butte Counties in California. Figure 2 shows the project limits as depicted on the

construction plans.

Figure 1 Project Location Map, District 03, Butte and Sutter Counties


Figure 2 Caltrans 03-3M5804 Project Limits

1.2 Project Objectives

The primary objective of the project is to provide maintenance for SR 99 in Butte Counties. A

secondary object is to evaluate and monitor the effectiveness of using RHMA-G at cooler

temperatures with night time paving.

The project included digging out both northbound and southbound lanes to a depth of 0.25 foot

plus the removal of 0.06 foot of open-graded asphalt concrete. This was replaced with 0.25 foot

dense graded ¾ inch HMA using PG 64-16 binder from PM 45.0 to PM 46.0. A RHMA-G

overlay with a thickness of 0.10 foot was placed over the entire surface including the shoulder

areas from Post Mile (PM) 44.4 to PM 46.0. The HMA and the RHMA-G materials were placed

at typical paving temperatures throughout the project.


1.3 Project Scope

This report includes the following chapters:

Chapter 2 describes the condition of the highway before the rehabilitation.

Chapter 3 describes the construction observations and data.

Chapter 4 includes a post construction evaluation of the RHMA-G and identifies future

plans.

Chapter 5 provides some findings observed from field inspections.

Chapter 6 provides conclusions, and recommendations for the future

2 Pre-construction Data

2.1 Existing Pavement Condition Survey

According to Ben Hargrove, Resident Engineer (R.E.) for Caltrans, District 3, SR 99 had

pavements in varying conditions. The most severely deteriorated areas were ground and repaved

with 3/4 inch HMA mix prior to the RHMA-G overlay. No crack sealing was performed on this

project. The R.E. said that he would have preferred using a grinder digout strategy for the entire

project due to the deterioration of the existing pavement.

Figure 3 Existing Pavement with Alligator Cracking, and Rutting

The existing pavement had fatigue cracking and some rutting. Most of the existing HMA

surfacing was placed in 1991, and a friction course hot mix asphalt open graded (HMA-O) was


placed afterwards. As part of the 1991 project, much of the asphalt concrete was removed for

cross-slope correction, and profile grade correction.

SR 99 is a primary highway with an Annual Average Daily Traffic (AADT) of approximately

12,200. This is an important route for agricultural goods, and is considered to be a regional

corridor. During harvest season, it can have a high percentage of truck traffic. Due to the route’s

importance as a regional corridor, it is important that it be maintained in good condition.

2.2 Existing Pavement Structure

The existing pavement structure for the NB and SB mainline is shown in Table 1.

Table 1 Pavement Structure Thickness Information

Existing Road Mix Asphalt Surfacing (feet)

Mainline

Existing Road Mix Surfacing (feet)

Left Shoulder from Previous Widening

Existing Road Mix Surfacing (feet)

Right Shoulder from Previous Widening

Material Thickness (feet)



HMA-O 0.06 HMA 0.25 HMA 0.15

HMA 0.15 AB 1.30 HMA Var.

HMA Various -- -- AB 1.30

HMA with PRF 0.10 -- -- -- --

Various AS Thicknesses not shown on

plans


plans


plans

2.3 Materials and Mix Design

The RHMA-G mix design was furnished by George Reed, Inc. and was verified by Caltrans,

District 3 Materials Laboratory and is included in Appendix B. Plant Mix #2013 G, Mix Design

Verification by District 3 Materials Laboratory—1/2" RHMA-G The rubberized binder was a

blend of PG 64-16, crumb rubber, virgin rubber, and oil extender. The binder design was done

VSS Technologies, and is included in Appendix C. Asphalt Rubber Binder Formulation The mix

design binder target value was 7.6% total weight of mix.

The 3/4” HMA Type A R10 dense graded mix was PG 64-16, with a binder target value of 5.0%

total weight of mix. The mix design verification is included in Appendix A. Plant Mix #2013,

Mix Design Verification by District 3 Materials Laboratory—3/4" HMA Type A (R10), Dense Graded

This test data was furnished by Ben Hargrove, R.E.

Figure 4 shows the binder storage for the PG 64-16 unmodified binder and the blended rubber

binder. Figure 5 shows the 5 aggregate bins which supply the cold feed to the dryer drum.


Figure 4 Binder Storage Tanks for PG 64-16 and Rubberized Binder

Figure 5 Aggregate Bins and Cold Feed to Dryer Drum of Aztec Plant


3 Construction Process

3.1 Construction Paving Plan

George Reed, Inc. proceeded very quickly on the paving for this project. His plant, located on the

Yuba River near Marysville, California and is capable of producing 4,500 tons per day. There

was one paving crew with newer equipment. On August 7, 2013, his crew was paving ¾” HMA

Type A R10. Construction took place from August 7 to early September 2013, between the hours

of 6:00 P.M. to 6:00 A.M. The paving was completed on August 13, 2011. The project was

accepted on September 6, 2013. Table 2 shows the location limits.

Table 2 Paving Post Mile Limits State Route 99

Post Mile Direction RHMA-G Mix

Location BUT 44.4/46.0 Both NB and SB RHMA-G Mix

Total Mileage 3.2 Miles (+/-)

The project included the replacement of 1,109.6 cubic yard of HMA for digouts, and the placement of

2,267 Tons of RHMA-G.

3.2 Weather During Construction

The weather during the time of construction was warm and sunny. The high temperatures ranged

from 82 o F to 95

oF. The low temperatures ranged from 57

o F to 62

oF. Table 3 is a weather

summary from Oroville Airport (KOVE) for August 2013 for the days that paving was performed

on the project. Since the paving was performed at night time, the low temperatures as shown in

Table 3 are representative of the actual paving temperatures.

Table 3 Weather Data for August 7-9 and 13, 2013

Date High oF Low

oF Sky Condition

Wednesday Aug. 7

82 57 Clear

Thursday Aug. 8

86 57 Clear

Friday Aug. 9

87 59 Clear

Monday Aug. 12

91 61 Clear

Tuesday Aug. 13

95 62 Clear


3.3 Construction Observations

The equipment used on the job consisted of the following:

Various belly dump trucks and trailers

1- Front Loader

2-Wirtgren 4-foot grinders

2-Self contained sweepers, owner operator

1-Distribution truck for emulsion

1-Paver with pick up machine

1-Shuttle Buggy

3-Rollers (2-steel wheel, and 1- rubber tire)

1-Water truck, owner operator

1-Pick up used as a pilot vehicle (not pictured)

1-One ton flatbed truck used for traffic control (not pictured)

George Reed, Inc., located in Marysville, CA, supplied the HMA and the RHMA-G mix for the

project. The RHMA-G was transported to the construction site by belly dumps. Figure 6 through

Figure 22 RoadTec MTV (shuttle buggy) Transfering Mix to Paver, Side Viewshows the

equipment that was on the project for August 7th through 12th, 2013. Figure 6 shows a typical

belly dump trailer that was used to transport grindings for disposal, and to transport HMA and

RHMA-G to the project. Figure 7 shows a Case front loader that was used on the project. Figure

8 shows one of two 4-foot Wirtgren grinders that worked in tandem. Figure 9 and Figure 10 show

the two self-contained sweepers which were used on the projects. Figure 11 shows the

distribution truck that was used for the emulsion tack coat. Figure 12 shows the Cedar Rapids

pick up machine from the front. Figure 13 and Figure 14 shows the Caterpillar Extend a Mat

screed. Figure 15 shows the Caterpillar paver with lighting from the back.


Figure 6 Typical Belly Dump

Figure 7 Case Front Loader


Figure 8 Wirtgren Grinder

Figure 9 Self-contained Sweeper


Figure 10 Self-contained Sweeper Dumping Grindings

Figure 11 Distribution Truck Used for Emulsion Tack Coat


Figure 12 Cedar Rapids Pick up Machine with Umbrella Lights, Front View

Figure 13 Cat 20-20B Adjustable Vibratory Screed, Side View


Figure 14 Cat 20-20B Adjustable Vibratory Screed, Back View

Figure 15 Caterpillar 1000D Paver with Umbrella Lighting, Back View


Figure 16 Water Tank

Figure 17 shows the two steel wheel Caterpillar CB 54 rollers used by George Reed, Inc. to

compact the RHMA-G mix for both immediate break-down of the mix and compaction rolling.

Figure 18 shows the Caterpillar PS 150C rubber tired roller used for finish rolling for the HMA.

Figure 19 shows the Caterpillar CB564D steel wheel roller used for the RHMA-G.

Figure 17 Cat CB 54 Vibratory Rollers


Figure 18 Caterpillar PS 150C Rubber Tire Roller

Figure 19 Caterpillar CB564D Steel Tire Roller

Figure 20 shows the paving operation near PM 44.4 with Cat paving machine and the RoadTec

Material Transfer Vehicle (shuttle buggy). The lighting was much better with the umbrella lights

than the direct lighting from light pods that have been used in the past.


Figure 20 Paving RHMA-G near PM 44.4

Figure 21 and Figure 22 show the RoadTec Material Transfer Vehicle (MTV) (shuttle buggy) that

was used to place the RHMA-G throughout the project.

Figure 21 RoadTec MTV (shuttle buggy), Front View


Figure 22 RoadTec MTV (shuttle buggy) Transfering Mix to Paver, Side View

Figure 23 through Figure 26 shows HMA mix temperatures from the windrow to the finish roller.

Figure 23 shows that the freshly placed mix in the windrow was 302oF. Figure 24 shows that the

mat temperature directly behind the paver was 286oF. Figure 25 shows that the mat temperature

behind the break down roller was 265oF. Figure 26 shows that the mat temperature between the

break down roller and the second roller was 256oF. Figure 27 shows that the mat temperature

between the second roller and the finish roller was 238oF.


Figure 23 Windrow Temperature in Front of Cedar Rapids Pick Up Machine

Figure 24 Mat Temperature Directly Behind Screed


Figure 25 Mat Temperature Between 1st

and 2nd

Rollers

Figure 26 Mat Temperature Behind 2nd

Roller

During the paving on the evening August 8th and the morning of August 9

th, the HMA mix started

out at 317 oF in the windrow at 7:30 P.M. and dropped to 282

oF by 1:30 A.M. on the 9

th. The

paving equipment used was the same as the previous night.

On the evening of August 12th through the morning of August 13

th, the ½-inch RHMA-G mix was

placed for the entire project. The mix temperatures were very consistent throughout the RHMA-


G placement of the 0.1 foot thick mat. Figure 26 shows roller 1 and 2 running in tandem for the

breakdown behind the screed.

Table 4 HMA and RHMA Temperature Data for August 7-9 and 12-13, 2013

HMA Temperature During Placement RHMA-G Temperature during

Placement

Location Mix Temperature Degrees Fahrenheit

Mix Temperature Degrees Fahrenheit

Windrow Varied on 8/8-9/2013 282-317, mostly 302

302

Behind Paver at Screed 263-276 280-288

Behind Roller No. 1 221-256 251 (in tandem w/roller 2)

Behind Roller No. 2 221-256 251 (in tandem w/ roller 1)

Behind Roller No. 3 175 Varied—not used in vibratory mode

Figure 27 Vibratory Rollers Directly Behind Paver

3.4 QC Data from Contractor

This project was not a Quality Control/Quality Assurance (QCQA) project, and Quality Control

(QC) data was not furnished by the Contractor for this project.

3.5 Testing Data from Caltrans

Table 5 shows Caltrans test results from the George Reed, Inc. plant located on the Yuba River.

The RHMA-G shows a very high stability of 34 when a minimum stability of 23 is specified.

The target value for the oil was 8.1 % by dry weight of the aggregate, which places the acceptable


range at 7.6 to 8.0 percent by dry weight of aggregate. This data was furnished by the Resident

Engineer, Ben Hargrove.

Table 5 Asphalt Binder Content and Stability, District 03 for RHMA-G

Date Sampled: 8/12/2013 Sampled by: Jeff McKeehan

Test No. Oil Content (actual) Stability (actual)

13-174 7.71 (DWA) 34

3.6 Emissions and Energy Consumption

On this project, the mix temperatures were approximately 320 oF at the plant during production.

The RHMA-G arrived at the job site at a temperature of 295 oF to 302

oF. The emissions

appeared to be typical for these mix temperatures.

3.7 Problems Encountered

The existing HMA as well as the open graded asphalt concrete had to be removed prior to

repaving over the existing bridge decks at Pine Creek Bridge (12-0028) at PM 45.72, and at

Campbell Creek Bridge (12-0029) at PM 45.70. The full depth grind was critical so that the

existing concrete bridge deck was not damaged, and that the new RHMA would not create an

overload to the existing bridge structures. On both sides of both bridges, digouts and tapers were

constructed so that the new paving over the bridges matched the new pavement’s profile grade.

Figure 28 shows Ben Hargrove, R.E., with inspectors checking the removal depth prior to

repaving.

Figure 28 Grinding on Bridge Deck Prior to Repaving

The RHMA-G transport trucks would arrive at the job site in groups on a sporadic basis causing

the paving crew to wait for loads. This also slowed down the overall production since the trucks

had to wait to unload. Sometimes bumps are caused by stop and go operations that result in

“must grind” conditions. There were no “must grinds” on this project after construction.


The roller operators for the steel wheel rollers appeared to roll several feet beyond the centerline

onto the opposite mat that had already cooled. When the rollers were in vibratory mode, this

could cause damage to the cool finished mat.

4 Post Construction

4.1 Appearance of Finished Mat

The surface of the RHMA-G mix was uniform and smooth riding after construction. Figure 29

shows the RHMA-G finished mat on August 13, 2013.

Figure 29 RHMA-G Finished Mat

Finished project photographs were taken on October 2, 2013. The ride quality was excellent and

there was no visible rutting. The surface of the RHMA-G mix was uniform and smooth riding.

The pavement appeared to be in as good of condition as it was prior to striping. No pavement

distresses were noted.

Figure 30 through Figure 36 are photos of the finished project at various locations (looking

north). Figure 30 shows the beginning of the project near Broyles Road, Figure 31 shows the

finished project with striping and rumble strips, Figure 32 shows the rumble strip on the the

northbound shoulder, and Figure 33 shows the rumble strip on the centerline of the highway.

Figure 34 shows a picture of the finished project looking north, Figure 35 shows Pine Creek

Bridge near PM 45.5, and Figure 36 shows the end of project at the Tehama County Line.


Figure 30 Beginning of Project, Looking North Near Broyles Road

Figure 31 Finished Project with Striping and Rumble Strips, Looking North


Figure 32 Finished Project, with Rumble Strips on Shoulders

Figure 33 Rumble Strip on Centerline


Figure 34 Finished Project, Looking North

Figure 35 Pine Creek Bridge near PM 45.5, Looking North


Figure 36 End of Project at Tehama County Line

Figure 37 shows the RHMA-G mat after nearly 2 months of traffic.

Figure 37 RHMA-G Finished Mat on October 2, 2013

4.2 Future Plans

The CP2C plans to continue monitoring this project for distress by inspecting it on regular

intervals. A field performance evaluation will be done and the test results will be documented

and compared to the laboratory test results with the approval of CalRecycle.


5 Findings Construction went well and the contractor had good equipment and good crews. The plant

appeared to be producing the RHMA-G mix without problems. The CP2C’s staff collected

samples at the plant that were sampled during production. The RHMA-G mix was placed on the

night of August 12th, and the morning of August 13

th in night time conditions.

The samples were tested by the CP2C Laboratory at Langdon Hall on the CSU, Chico campus.

To establish the comparison between the conventional HMA, and the RHMA-G both sets of

samples were prepared and ran on the James Cox and Sons' 4-point bending beam fatigue tester

shown in Figure 38.

Figure 38 James Cox and Sons, 4-Point Fatigue Testing Apparatus

The testing used AASHTO Test 321-07: “Determining the Fatigue Life of Compacted HMA

Subjected to Repeated Flexural Bending” to test the SR 99 samples. The following procedures

were used for obtaining the test results:

Beam specimen is subjected to a sinusoidal loading at a frequency of 10 Hz and a

temperature of 20 °C


Desired initial strain (250 to 750 microstrain) is selected such that the specimen will

undergo at minimum of 10,000 load cycles before failure

Failure life is defined as a stiffness reduction at 50% of the initial stiffness

Table 6 shows the conventional HMA data, and Table 7 shows the RHMA data. Figure 39 shows

a log-log plot of the data for both HMA and RHMA-G. There appears to be more variability in

the RHMA test results, however in every strain level, the RHMA-G outperforms the HMA mix

by more than double the number of repetitions.

Table 6 State Route 99 Conventional 4-Point Fatigue Testing Results

Material Source Sample ID

Strain Level (micro strain)*

# Cycles to Failure

Conventional George Reed 1-1 350 7455








Conventional George Reed 3-1 250 26343 *Note: Conventional HMA did not meet the criteria for testing at the 400 micro strain level

Table 7 State Route 99 RHMA 4-Point Fatigue Testing Results

Material Source Sample

ID

Strain Level (micro strain)

# Cycles to Failure

Asphalt Rubber George Reed 3-2 400 70208












900800700600

500

400

300

200y = 3031.2x-0.241

R² = 0.9077

y = 1414.5x-0.119

R² = 0.8208

100

1000

1,000 10,000 100,000 1,000,000 10,000,000

Stra

in L

eve

l (lo

g)

Fatigue Life (# of cycles) log

US 99 Conventional vs RHMA

Conventional

Asphalt Rubber

Figure 39 State Route 99 Comparison for Conventional vs. RHMA-G for 4-Point Fatigue Testing

It is also recommended by the CP2C that the jobs should have adequate staffing to monitor key

processes during plant production as well as field operations. It is recommended by the CP2C

that more RHMA-G mix projects be placed for further evaluation.

6 Conclusions and Recommendations This project was constructed for a total cost of $650,700. This equates to $17.33 per square yard

for this maintenance project. This RHMA-G appeared to have no visible distresses on March 18,

2014. Overall, the pavement is in very good condition.

The following conclusions can be drawn from this project’s test results:

RAC does outperform conventional HMA.

o The RHMA laboratory samples sustained more than twice the number of micro

stain cycles before failing.

o The RHMA-G showed superior performance at all micro strain levels.

This performance was documented in lab studies from material samples collected on this

project.

The superior laboratory performance of the RHMA indicates a substantial long term cost

savings. With variability, the cost savings may be around 39%1.


An important extension of this study is to document that the field performance of RHMA-G for

this project follows the laboratory performance. To obtain this documentation, it is recommended

that the CP2C continue to monitor this project to determine when distresses start to appear. The

distresses that will be monitored are raveling, cracking, and rutting. Once the pavement is

showing distress, the performance of this RHMA-G can be compared to convention mixes, such

as RHMA dense graded mix, and HMAs with unmodified binders in similar climate conditions.


Abbreviations and Acronyms AADT Annual Average Daily Traffic

Caltrans California Department of Transportations

CP2 California Pavement Preservation Center

HMA Hot Mix Asphalt

HMA-O Hot Mix Asphalt Open Graded

PG Performance Grade

PM Post mile

QC Quality Control

QCQA Quality Control and Quality Assurance

RAC Rubberized Asphalt Concrete

R.E. Resident Engineer

RHMA-G Rubberized Hot Mix Asphalt Gap Graded

SB Southbound

SR State Route

NB Northbound


Appendix A. Plant Mix #2013, Mix Design Verification by District 3 Materials Laboratory—3/4" HMA Type A (R10), Dense Graded











Appendix B. Plant Mix #2013 G, Mix Design Verification by District 3 Materials Laboratory—1/2" RHMA-G












Appendix C. Asphalt Rubber Binder Formulation







Bibliography Caltrans Plans and Specifications for Contract No. 03-3M5804, dated December 3, 2012.

George Reed, Inc., various personnel, August 2013

Hargrove, Ben, Caltrans District 3 Resident Engineer, August 2013.

Endnotes

1 Cheng, DingXin and R. Gary Hicks, "2014 Tire Conferende," April 2014.

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