Report Number: CP2C

Transcription

1 Evaluation of RAC-O-HB Project FRE I-5-PM 0-38 HB project on I-5 north of Bakersfield Report Number: CP2C July 7, 2007 California Pavement Preservation Center 203 Langdon Hall California State University Chico, California (530)

2 PROJECT SUMMARY PAGE Technical Report: CP Title: Evaluation of RAC-O-HB Project FRE I-5-PM 0-38 Author: Way, G. B. Prepared for: California Department of Transportation Office of Pavement Preservation Division of Maintenance 5900 Folsom Blvd Prepared by: George B. Way, P.E., consultant California Pavement Preservation Center California State University, Chico Chico, CA Client Reference No.: Contract No Date: July 7, 2007 Abstract: This report documents the performance of a 30 mm Rubberized Asphalt Concrete Open- Graded High Binder (RAC-O-HB) over an old, distressed Portland cement. The project is located FRE I-5, Post Miles 0-38 in District 6 in 2000, and approximately 70 miles north of the city of Bakersfield. This section of I-5 has more than 2,748,000 annual ESAL s. After 7 years of traffic, the RAC-O-HB is still firmly bonded to the PCC surface, with only limited transverse and/or reflective cracking. An estimate of close proximity noise indicates this thin surface treatment is quieter than either old traditional hot mix asphalt or nearby PCC surfaces by about 4 dba. Keywords: Rubberized Asphalt, RAC-O-HB, Thin Surface Treatments i

3 ACKNOWLEDGEMENT The author thanks Dr. Gary Hicks and Dr. Shakir Shatnawi for their assistance on this project. In addition much thanks to Dr. Kamil Kaloush of Arizona State University who assisted in reviewing the project and assembling the field measurements and observations. Also thanks to Luiz Mello for helping with the noise measurements and data recording. Luiz is an Arizona State University graduate research assistant from Brazil studying for his PhD in Civil Engineering. 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 no necessarily reflect the official views or polices of the State of California or the Federal Highway Administration ii

4 Table of Contents 1.0 INTRODUCTION THE RAC-O-HB STRATEGY PERFORMANCE OF RAC-O-HB PROJECTS BACKGROUND OF FRE I-5 PM 0-38 PROJECT LOCATION AND GENERAL INFO. OF I-5 PROJECT CONSTRUCTION PERFORMANCE REVIEW OF FRE I-5 PROJECT Cracking Level Rut Depth Measurement Smoothness Rating PCI Rating Noise measurement FINDINGS AND CONCLUSIONS... 8 Appendix A- Example RAC-O-HB Mix Design.. 9 Appendix B- Photos taken in each area 10 Appendix C- Example PCI computer screen copies.17 Appendix D- Lexus Car, Noise meter and example of noise measurement computer screen...18 List of Tables Table Summary of RAC-O-HB Projects in California 3 Table 2- Noise Measurements. 9 List of Figures Figure 1-District 6 Project FRE I-5 PM 0-38 Location... 1 Figure 2 Vicinity map showing location of FRE I-5 project... 4 Figure 3 California PG grade zones.. 5 Figure 4- Distress areas 6 Figure 5- Rut Depth Measurement... 7 iii

5 1.0 INTRODUCTION This report documents the performance of a Rubberized Asphalt Concrete Open-Graded High Binder (RAC-O-HB) project placed on FRE I-5, Post Miles 0-38 in District 6 in 2000 ( Figure 1). This was the second time Caltrans tried this product even though a very similar product like it has been extensively used by the Arizona Department of Transportation (ADOT) since The report focuses primarily on reporting on the performance of the RAC-O-HB mix after seven years of service. Information in this report was compiled from the following list of historical data related to the project: Correspondence and draft report information from Dr. Gary Hicks. District correspondence by . Site Visit to both RAC-O-HB projects, May Figure 1-District 6 Project FRE I-5 PM 0-38 Location 1

6 1.1 THE RAC-O-HB STRATEGY Rubberized asphalt concrete (RAC) is a material produced for hot mix applications by mixing asphalt rubber with graded aggregate. RAC-O indicates that asphalt rubber is mixed with open-graded aggregate; RAC-O-HB indicates that asphalt rubber is mixed with open-graded aggregate, but with higher binder content. Appendix A shows a typical RAC-O-HB mix design as placed on the SAC-99 project. Mix design data was not available from the district offices. The primary difference between RAC-O and RAC-O-HB is the features or functions they provide. RAC-O provides a durable, highly flexible pavement surface with enhanced drainage and frictional characteristics, reduces splash and spray to improve visibility during wet weather, reduces hydroplaning in wet conditions to reduce potential for skidding, provides increased resistance to reflective cracking and oxidation, and provides a smooth ride. RAC-O-HB is used mainly to restore surface friction and provide improved resistance to fatigue and reflective cracking, as well as to stripping and oxidative aging. These features increase the durability of the pavements. The other difference is the binder content. RAC-O is designed using the California Test 368 with asphalt rubber binder content set at 1.2 times the optimum neat asphalt binder content with a check test for drain off. Typical binder content would be about 6.2 % by weight of dry aggregate. RAC-O-HB is designed according to the RAC-O procedure, but the multiplier for asphalt rubber binder content is increased to Generally, RAC-O- HB mixes have at least 8.5 % binder by weight of the dry aggregate. By comparison the same type of mixes as placed in Arizona by the ADOT have an average asphalt rubber binder content of 9.1 % by weight of the mix. The 9.1 % is equivalent to 10.0 % by weight of the dry aggregate. RAC-O-HB mix offers many benefits to the user. It can provide the following attributes: Noise reduction over concrete pavements. This has been proven in the state of Arizona. Improved durability and resistance to reflection cracking. However, when placed over badly distressed pavement, surface preparation work must be undertaken. 1.2 PERFORMANCE OF RAC-O-HB PROJECTS IN CALIFORNIA Several projects have been constructed with RAC-O-HB mixes in California and they have performed extremely well. A summary of the projects is given in Table 1 below. 2

7 Table Summary of RAC-O-HB Projects in California Project PM Lane Miles Date Const. Range in % Binder Pre-Overlay Surface Current Condition SAC Concrete Pavement with considerable distress FRE I Asphalt Concrete over a crack and seat concrete which had varying degree of rutting and cracking MONO 395 MONO Asphalt concrete with some thermal cracking Asphalt concrete with thermal and alligator B cracking SBD Asphalt concrete with some minor distress SBD Asphalt concrete with some minor distress Fair Condition PCI was not measured Very good condition with minor reflected concrete joints. Some concrete punch outs. PCI= 87 Good condition with thermal cracks reflected through. PCI= 80 Fair condition With small thermal Cracks-2006 Overlaid in 2006 Surface wear, low severity random cracks. Overall condition good to excellent. PCI= 88 Four distinct areas of performance from good to excellent. Surface wear, random and transverse cracks, some rutting and potholes and patches. PCI = 77 3

8 1.3 BACKGROUND OF FRE I-5 PM 0-38 PROJECT The RAC-O-HB was placed over a pre-existing HMA overlay of a cracked and seated PCC pavement. The HMA surface was in good to fair condition, with some cracking and rutting. 1.4 LOCATION AND GENERAL INFORMATION OF FRE I-5 PM 0-38 PROJECT The FRE I-5 project is located in District 6, on Interstate 5 approximately 70 miles north of the city of Bakersfield. Figure 2 is a vicinity map showing the location of the project. The project is within a valley farming area where the high temperature in the summer can reach over 100 F and in the winter it can be as cold as 32 F. The annual rainfall averages 5.7 inches. The approximate elevation of the project is 500 feet. The project is within the asphalt PG grade zone as shown in Figure 3 which is indicative of a relatively mild but warm climate. Interstate 5 is a very heavily trafficked highway with a very high percentage of large and heavy trucks. Caltrans records indicate an AADT of 33,500 two way daily vehicle traffic, with 8,899 trucks. The truck ESALs loading is estimated to be 2,748,000 per year. FRE I-5 PM 0-38 Figure 2 Vicinity map showing location of FRE I-5 project 4

9 Figure 3 California PG grade zones 2.0 CONSTRUCTION The RAC-O-HB binder content range was 8.5% to 10%. The specific mix design information for this project was not available. 3.0 PERFORMANCE REVIEW OF FRE 5 PROJECT On May 21, 2007, a review of the pavement condition was made to determine the current condition of the pavement after 7 years of service under heavy Interstate 40 traffic conditions. The project was reviewed by George B. Way and Dr. Kamil E. Kaloush of Arizona State University. They were assisted by Luiz Mello and post graduate student studying under Dr. Kaloush. Measurements taken on project: Observation of cracking level, extent and severity Numerous Photos, digital and 35 mm Rut depth, four foot straightedge Rating of smoothness PCI rating Noise measurements 5

10 3.1 Cracking Level A review was made of the type of cracking and level of severity and extent. In driving the length of the project in both directions and stopping at several locations it appears that the degree of cracking and distress is essentially the same throughout the project and in both the north bound and south bound direction. Figure 4 shows the limits of the project and the approximate locations where both pictures and rut depth measurements were taken of the pavement distress. Appendix B shows some of the pictures taken in each of the areas and representative of the observed condition. It should be noted that Dr. Gary Hicks supplied some of the pictures. Figure 4- Photo and Rut Depth locations At each of the photo locations and along the pavement in general the cracking was described in manner that would be useful to calculate the Pavement Condition Index (PCI). Below are the general descriptions of the cracking for each for each location. NB PM 2- Smooth ride, joints and random transverse cracks reflecting through surface. A few occasional punch outs were noted in right wheel path travel lane. NB PM 16- Punch out past bridge need of repair, could see thickness of HB friction course. Shattered concrete slab, center of slab, lots of movement of concrete slab: leaving slab beyond the bridge. Very little cracking. May be why section selected for fog seal experiment. However, we do not see the need for any fog seal of the whole project. NB PM Very little cracking. May be why section selected for fog seal experiment. However, we do not see the need for any fog seal of the whole project. Good ride, few cracks. Very good ride, virtually no cracks. Wondered 6

11 why it was necessary to remove open graded. Some punch outs in right wheel path travel lane. More joint cracks, cracks not sealed. NB PM 30- Stopped at interchange, pavement looked very good. Granite USA marked painted indicating some construction. Ride good, minor damage, joints reflecting through and random cracks. No evidence any maintenance required SB 30-0 Very quiet, very smooth ride, few joints and random transverse cracks reflecting through. Very good ride, again few joints and random transverse cracks reflecting through. Also, very few sealed cracks. Very few sealed cracks. Sealed transverse cracks and right edge line cracks, ride not as good as before, more sealed cracks. 3.2 Rut Depth Rut depth measurements were taken with a four foot straightedge and ruler. Measurements were recorded to the nearest 1/8 of and inch. As an illustration of the rut depth measurement method used is the photo shown in Figure 5. The rut depth was minimal on the project, no more than 1/8 inch. Figure 5- Rut Depth Measurement 7

12 3.3 Smoothness Rating The ride smoothness was subjectively rated good to very good throughout the project. 3.4 PCI Rating The Pavement Condition Index was calculated by use of a computer program developed by Dr. Kamil Kaloush and referred to as the Highway Consulting Services PCI program. This program is patterned after ASTM D 5340, Standard Test Method for Airport Pavement Condition Index Surveys an adapted for evaluating flexible, rigid and composite highway pavements. Dr. Kaloush has used this PCI method and computer program for over 15 years and evaluated over 4,000 different pavement sections in the United States and in various foreign countries. Appendix C shows example copies of the computer screen output for this project. By reviewing the photos and condition notes and using the computer program the overall PCI rating for each of the review locations is as follows: NB - Overall NB Rating PCI = 84 SB- Overall SB Rating PCI = 90 The overall PCI rating is 87 which is considered as an excellent as shown on the ASTM D 5340 rating scale. 3.5 Noise measurement Noise measurements taken on various surfaces have shown that a RAC-O-HB surface can reduce the tire pavement interface noise. During the review of the RAC-O-HB surfaces noise measurements were taken inside the car. All the RAC-O-HB sites were reviewed while driving in a 2001 Lexus ES 300 Sedan, shown in Appendix D. The measurements were taken with a recording noise meter, SPER Scientific Model as shown in Appendix D. The noise measurements were taken at 65 MPH with the windows closed and the air conditioner in the low fan level. Appendix C shows a copy of the computer screen which gives the average, maximum and minimum noise level for the recorded test interval. Table 2 shows the noise measurements as they were taken during the course of reviewing the various sections. By chance while traveling north to the project several different and older surfaces of concrete and asphalt were noted as sounding somewhat noisy. The noise measurements were taken on these other sections outside of the RAC-O- HB project for comparative purposes and as expected the RAC-O-HB noise readings were quieter. As can be seen in Table 2 the RAC-O-HB noise readings inside the car vary to some degree, however for the most part they are still relatively low considering the age of the pavement. 8

13 Table 2- Noise Measurements, highlighted measurements taken on FRE I-5 project Surface Type PM Start PM End Noise dba Noise dba Noise dba County Route Dir. Type Start End Average Maximum Minimum Kern I-5 NB PCC Kern I-5 NB AC Kern I-5 NB AC Kim I-5 NB AC Fresno I-5 NB HB Fresno I-5 SB HB Fresno I-5 SB HB FINDINGS AND CONCLUSIONS After reviewing project FRE I-5 RAC-O-HB, PM 0 to 38, the following findings and conclusions apply: The project was constructed in 2000, however little is known about the design or construction other that the final one inch wearing course is a RAC-O-HB mix placed on top of an older section of plain jointed concrete. The RAC-O- HB mix is of a darker color than the shoulder area which would indicate that a good quantity of asphalt rubber was used in the mix. Apparently the quantity of asphalt rubber used in the mix is in the percent range as a percentage of the dry aggregate in the mix. Numerous transverse concrete joints have reflected through the RAC-O-HB, however the cracks are narrow or healed over. For the most part the cracks are not sealed. There are some concrete punch outs but amazingly the HB mix is still stuck to the concrete. The ride smoothness is overall very good. The rut depth was minimal, no more than 1/8 inch. The PCI values indicate that the RAC-O-HB is generally performing in the very good category. The performance of this project is similar to pavements constructed in Arizona using a similar material referred as an asphalt rubber open graded mix. Although based on the reviewers experience in general the Arizona mixes seem to perform a little better when placed over the concrete this could be due to more asphalt rubber in the mix. Likewise concrete punch outs are relatively rare in Arizona. In Arizona this could be due to the concrete either 9

14 being thicker than the California pavement or that Arizona Interstate concrete pavements have transverse dowel reinforcement. It should be noted that the Arizona asphalt rubber open graded mixes use a Type 1 asphalt rubber binder whereas the California mixes use a Type 2 asphalt rubber binder. Also for the Arizona mixes the percent asphalt rubber is based on the weight of the total mix, thus for the same percentage the Arizona mixes have a little more asphalt rubber binder than the California RAC-O-HB. Noise measurements of the RAC-O-HB mix seem comparable to those measured in Arizona and are reasonably quiet. Overall this project is performing very good with only minimal distress and no maintenance treatment appears needed at this time. 10

15 Appendix A Example RAC-O-HB Mix Design 11

16 Appendix B Photos taken at various locations on the project 12

17 13

18 14

19 15

20 16

21 Dr. Gary Hicks Selected Photos from the FRE I-5 Project (March 1, 2007) MP 30 looking north At MP 30 17

22 Dr. Gary Hicks Selected Photos from the FRE I-5 Project (March 1, 2007) At MP 15 Northbound at MP 0.0 Northbound at MP 4.5 At MP

23 Appendix C Example PCI computer screen copies PCI for I-5 North Bound, PM

24 Appendix D Lexus Car, Noise meter and example of noise measurement computer screen Noise meter as positioned for test in the back seat of the car 20

25 Example of a noise screen showing average, maximum and minimum noise measurements 21