Innovation Project: Interlayers on Highway 36 near Chester, California

Transcription

1 Innovation Project: Interlayers on Highway 36 near Chester, California Highway 36 One Year After Report Number: CP March 12, 2008 California Pavement Preservation Center 203 Langdon Hall California State University Chico, California (530)

2 PROJECT SUMMARY PAGE Technical Report: CP Title: Innovation Project: Interlayers on Highway 36 near Chester, California Authors: Lance Brown, P.E., and M. Stroup-Gardiner Prepared for: CALTRANS California Department of Transportation Client Reference No.: Project 02-PLU-036 Prepared by: California Pavement Preservation Center Date: January 24, Langdon Hall California State University Chico, California Abstract: In Plumas County California, Caltrans placed 4 interlayer test sections. The test sections were overlaid with 30mm rubberized asphalt concrete. The interlayer systems used were: 1) fiberglass polyester paving mat; (Paving mat), 2) polymer modified emulsion (PME) chip seal;pmcrs-2h 3) asphalt rubber (AR) chip seal and 4) modified binder (MB) chip seal. The purpose of these test sections is to determine the effectiveness of an interlayer system to enhance performance of a surface treatment and reduce field maintenance of pavements that have exceeded the design life. Approximately ½ mile of the non-standard MB chip seal did not receive an overlay to allow an evaluation of this new hot applied chip seal. After 1 year of weather and traffic, all four of the test sections are performing well. The only distresses seen in the surface is a limited number of transverse cracks and slight oxidation of the pavement. The MB chip seal, with no hot mix asphalt layer, is showing a slightly higher severity of transverse cracks. It is not clear if the transverse cracks are a function of the RAC-G binder properties or reflection cracks from the distresses in the old pavement. Keywords: Interlayers, Reflective Cracking, Chip Seals, Asphalt Rubber, Paving Mat i

3 ACKNOWLEDGEMENTS The author is grateful to the assistance provided by Dr Tom Ferrera, CP2 Center, of the California Pavement Preservation Center. The authors would also like to thank Scott Dmytrow, Mike Fain and Karl Meyers from Telfer Oil, Inc., Caltrans Matt Gowan (Project Engineer), Karlie Smith (Assistant Project Engineer) and Fred Chaffin (Resident Engineer) for their valuable contributions on this project. 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 INTRODUCTION... 1 SECTION 1 Paving Mat with 30 mm RAC-G SECTION 2 - POLYMER MODIFIED EMULSION (PME) INTERLAYER SECTION 3 ASPHALT RUBBER (AR) CHIP SEAL INTERLAYER Materials...14 AR Interlayer Test Sections...16 SECTION 4 MODIFIED BINDER (MB) CHIP SEAL INTERLAYER RAC-G MIX SHOULDERS SUMMARY LESSONS LEARNED REFERENCES APPENDIX A Innovation Pre-Proposal, Proposal, and Final Report Format APPENDIX B Fiberglass/Polyester Paving Mat APPENDIX C Asphalt Rubber Seal Coat NSSP APPENDIX D Modified Binder Seal Coat APPENDIX E Polymer Modified Emulsion Seal Coat TABLE OF TABLES Table 1. Layout and Information about Test Sections... 2 Table Truck Traffic on Highway 36 at Plumas/Lassen County Line... 6 Table 2. Location and layers present in the existing HMA pavement Table 4. Physical Properties of fiberglass polyester paving mat Table 5. Properties of emulsion residue after evaporation Table 6. Caltrans screening requirements Table 7. Upper PG temperature requirements for unmodified Table 8. Requirements for asphalt modifiers used in asphalt rubber blends Table 9. Material requirements for scrap tire and high natural rubber CRM Table 10.Required blended asphalt rubber properties Table 11. Caltrans screening requirements for asphalt rubber chip seals (hot applied) Table 12. Caltrans RAC-G requirements for aggregates iii

5 TABLE OF FIGURES Figure 1. Project Location near Chester, California Figure 2. Typical pre-construction roadway condition Figure 3. Typical pavement cross sections for Highway 39 near Chester, California interlayer projects Figure 4. Pavement layers for innovation project 02-PLU Figure 5. Hourly traffic distribution for PM 14 through PM18.5 (2006) Figure 6. Existing ride quality before placing the surface treatments Figure 7. Existing rut depths before placing the surface treatments Figure 8. Existing pavement transverse cracking before placing the surface treatments Figure 9. Existing pavement patching before placing the surface treatments Figure 10. Existing pavement deflection data before placing surface treatments Figure 13. Section 2 before and after leveling course Figure 14. Typical condition of PME interlayer before, during, and 1 year after construction Figure 15. Typical structural section in Section 3 (AR chip interlayer) Figure 16. AR chip seal interlayer after placement and 1 year after construction Figure 17. Typical digout repairs prior to leveling course and typical structural thickness Figure 18. MB chip seal interlayer immediately and 1 year after construction iv

6 INTRODUCTION Pavement interlayers are materials or combinations of materials that can be placed within a pavement system during new construction, rehabilitation or preservation in conjunction with an overlay or surface treatment to extend pavement service life (MTAG Chapt. 12 draft 2008). In addition, some types of interlayer systems allow for the reduction of an overlay-only thickness due to the strain and/or stress relief. Past experience in California with asphalt rubber chip seals and non-woven polyester interlayers over crack and seat or asphalt overlays has been positive. However, Caltrans has limited experience with other interlayer products combined with thin, nonstructural surface mix overlays. One of the few interlayer projects constructed and monitored over 13 years was sponsored by the California Integrated Waste Management Board (CIWMB) and constructed at the Esparto site in After 13 years, the flexible interlayer and thin overlay sections have performed well. As noted in the conclusions of a report prepared in 2004 all test sections at the Esparto Site exceeded the expected design life of 5 to10 years. In California, state pavement preservation and maintenance overlay projects are defined as have a thickness of less than 30 mm. Capital preventive maintenance (CaP-M) projects are defined as overlays of no more than 50 mm. Overlays thicker than 50 mm are considered rehabilitation projects. When a project is identified as being a preservation project, the source of funding will therefore dictate the thickness of overlay that can be placed over the interlayer. Some interlayer systems require a minimum of 37.5 mm overlay thickness so they may be eliminated from consideration for preservation or maintenance projects. The innovative project constructed by Caltrans in Plumas County was constructed under the preservation program funding, so the overlay was limited to 30 mm. The purpose of this innovative project is to compare four interlayer systems (3 chip seals and one paving mat) to the control (untreated) section. This report describes the site selection, construction, and one year after construction performance of these test sections. Nonstandard special provisions, recommended manufacturer paving mat suppliers, and the innovation project submission documents are included in appendices.

7 PROJECT DESCRIPTION The project was constructed in Plumas County, State Route (SR) 36 at postmile 14 to (Figure 1). State Route 36 is a 2 lane convention highway with an average daily traffic of from 2200 to 5000 vehicles per day. The site selected for the test was a location in a poor state of repair (Figure 2), and low on the Districts priority for rehabilitation as an ultimate form of repair. The damage was beyond maintenance therefore a nonconventional means of adding service life was utilized in the form of a 2-layer system as known as an interlayer. Table 1 identifies the type of interlayer that was placed in each section of the project. Figure 1. Project Location near Chester, California. Table 1. Layout and Information about Test Sections (Specifications in Appedices B, C, and D) Section Number Post Mile Interlayer Used Surfacing Fiberglass/Polyester Paving Mat 30 mm RAC-G Transition None 30 mm RAC-G PME Chip Seal 30 mm RAC-G Transition None 30 mm RAC-G AR Chip Seal 30 mm RAC-G Transition None 30 mm RAC-G MB Chip Coat 30 mm RAC-G Seal only None MB Chip Seal 2

8 Typical existing pavement distresses on Highway 36, east of Chester, CA PM 14.0 to Figure 2. Typical pre-construction roadway condition. 3

9 Figure 3 shows the typical pavement cross section of the pavement structure. Figure 4 details the interlayer test section materials from the bottom (subgrade) to the surface course (30 mm of RAC-G). The project site was thoroughly reviewed for severity and cross section to determine the most appropriate location for each interlayer material. Photos of the condition of the roadway and core for thickness determination for each interlayer test section are shown in the following sections. Figure 3. Typical pavement cross sections for Highway 39 near Chester, California interlayer projects. 4

10 -PM mm RAC Type G -PM PM mm RAC Type G -PM PM mm RAC Type G -PM PM mm RAC Type G -PM MB Chip Seal Only -PM Project Limits: Paving Mat PME Chip Seal AR Chip Seal MB Chip Seal 3/16- leveling course (as required 0-38 mm) Existing (Failed) Pavement (Digouts as Required) AC Basic Mix Design: Type Binder Type Aggregate PG Type G (Paramount) gap-graded 3/4-inch % Oil 7.70% % Rubber 18-20% Compaction 96-97% Lime Ratio 1.20% Seal Coats: Type Binder PMCRS-2H Modified Binder Application Rate 0.33 gal/yd gal/yd gal/yd 2 Source of Binder VSS Emultech Type Aggregate 1/2-inch 1/2-inch 3/8-inch, hot applied App Rate of Aggregate lb/yd 2 30 lb/yd 2 28 lb/yd 2 Source of Aggregate Tiechert/Perkins?? Lime Ratio Paving Mat: 100% polypropylene staple fiber mat material, needlepunched, thermally bounded on one-side, 140 g/m 2, 0.45 KN grab tensile strength, 50% elongation at break, 900 g/m 2 asphalt retention. (3/16 minus) Leveling Course: Type Binder PG Type A Type Aggregate 3/16-inch % Oil 7.70% Placement Method Placed with Shuttle Buggy and vibrating screed paver. Tracked-In with pneumatic tires. Lime Ratio 1.20% Existing AC Figure 4. Pavement layers for innovation project 02-PLU

11 Traffic information was also provided by District 2. The traffic levels reported for 2006 on the Caltrans Website were at 3,050 for the peak month Average Daily Traffic (ADT) and at 2,300 Average Annual Daily Traffic (AADT). Fourteen percent of the traffic was reported to be trucks for the 2005 data on the Caltrans Website; the AADT was 2,300 for The distribution of truck traffic in the AADT is shown in Table 3. Hourly traffic counts for the section are shown in Figure 10. Table Truck Traffic on Highway 36 at Plumas/Lassen County Line Number of Axels Number of Trucks Percentage of Trucks Percent of AADT All Trucks East Bound West Bound Time, h :00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00 Hourly Traffic Count Figure 5. Hourly traffic distribution for PM 14 through PM18.5 (2006). Information was collected prior to construction by District 2 for ride quality, rut depths, alligator cracking, transverse cracking, and patching. Figure 5 shows a ride quality expressed at the International Roughness Index (IRI) was typically less than 100 in/mile for the first one mile of the project. Figure 6 shows the rutting was also very low (less than 5mm), in the first mile of the project while the remainder of the roadway had rut depths varying widely from 5 to 25 mm. Conversations with industry on the history of this portion of the roadway yielded the information that a leveling course had been placed a couple of years earlier. While the leveling course did not significantly reduce the cracking noted in this section (Figures 7 and 8), it does provide an explanation for the smoother ride and lack of rutting 6

12 IRI, EB IRI, WB Paving Mat + 30 mm RAC-G PME Chip + 30 mm RAC-G AR Chip + 30 mm RAC-G MB Chip + 30 mm RAC-G MB Chip IRI, in/mi Posted Miles Figure 6. Existing ride quality before placing the surface treatments. Rutting, EB Rutting, WB Paving Mat + 30 mm RAC- G PME Chip + 30 mm RAC-G AR Chip + 30 mm RAC-G MB Chip + 30 mm RAC-G MB Chip Rut Depth, mm Posted Miles Figure 7. Existing rut depths before placing the surface treatments. The cracking recorded for the pavement condition survey showed the most common distress was the transverse cracking (Figure 7). While this figure shows lower transverse cracking between PM 16.5 and 18.5, this is only because the alligator cracking and patching of the roadway in this area was so extensive that the transverse cracking could not be singled out. Figure 8 shows about half of the project had a fair amount of patching (about PM16.5 to PM18.5). This is also the portion of the road that had most of the dig out repairs prior to placing the interlayers. The average length the digouts was 20m and the total tonnage equaled was 370 tonnes. This amount was insignificant to the overall distress. A leveling course was placed on the remaining four miles of the project prior to the placement of the chip seal interlayers and chip seal only sections. 7

13 Transverse Cracking, EB Transverse Cracking, WB Extent of Transverse Cracking Paving Mat + 30 mm RAC-G PME Chip + 30 mm RAC-G AR Chip + 30 mm RAC-G MB Chip + 30 mm RAC-G MB Chip Posted Miles Figure 8. Existing pavement transverse cracking before placing the surface treatments. Patching, EB Patching, WB 250 Patching, Ft Paving Mat + 30 mm RAC- G PME Chip + 30 mm RAC-G AR Chip + 30 mm RAC-G MAB Chip + 30 mm RAC-G MAB Chip Posted Miles Figure 9. Existing pavement patching before placing the surface treatments. The falling weight deflectometer (FWD) testing was conducted pre-construction to provide a baseline for post-construction stiffness measurement comparisons. This post construction testing is expected to provide information on the strain and/or stress dissipation characteristics of the interlayers. Table 2 indicates the location, type of structural layer, the total thickness of the section, the type of base material, and remarks from the testing staff. Figure 9 shows the deflection varied between and mils; generally similar deflections were obtained when comparing the East and West 8

14 bound lanes. That is, if the deflection was high in the East Bound lane, it was also likely high in the West bound lane. Table 3. Location and layers present in the existing HMA pavement. Test Layer 2 Section (Struct. Sect.) Paving Mat + RAC-G PME Chip + RAC-G Core Hole Location (PM, Lane No., Direction) Total Core Thickness Layer 5 (Base Matrl) , L1, EB 0.40 DGAC 0.40 AB INTACT Remarks 14.48, L1, WB 0.50 DGAC 0.50 AB 0.32' FROM TOP , L1, WB 0.48 DGAC 0.48 AB INTACT , L1, EB 0.50 DGAC 0.50 AB 0.27' FROM TOP , L1, EB 0.44 DGAC 0.44 OG INTACT (HOLE WAS MEASURED) 16.56, L1, EB 0.75 DGAC 0.75 AB INTACT , L1, WB 0.73 DGAC 0.73 AB 0.09' FROM TOP AR Chip + RAC-G MB Chip + RAC-G , L1, EB 0.50 DGAC 0.50 AB INTACT MB Chip Only 18.20, L1, WB 0.52 DGAC 0.52 OG INTACT DGAC: Dense graded asphalt concrete AB: Aggregate Base OG: Original Ground EB: East Bound WB: West Bound Deflection, EB Deflection WB Paving Mat + 30 mm RAC-G PME Chip + 30 mm RAC-G AR Chip + 30 mm RAC-G MB Chip + 30 mm RAC-G MB Chip Deflection, mils Posted Miles PM locations estimated from deflection file notes Figure 10. Existing pavement deflection data before placing surface treatments. 9

15 SECTION 1 Paving Mat with 30 mm RAC-G Figure 11 shows the original condition of this specific section prior to construction and the structural thickness of the pavement. There is about 110 mm of HMA with four visible layers in the core. The existing leveling course on this section of roadway is easy to see in this figure. EB 36 LANE 1 PM EB 36 LANE 1 PM C8201 PLU /18.4 TEST 5 WB 36 LANE 1 PM C8201 PLU / C8201 PLU /18.4 Figure 11. Section 1 Existing pavement surface and structural thickness. The paving mat was placed on September 1 and 2, The surface was cleaned prior to spraying the PG64-10 hot applied binder, which was immediately followed by the placement of the paving mat fiberglass paving mat. The paving mat was overlaid with 30 mm of gap graded rubberized asphalt concrete (RAC-G) mix. Documentation and background information for the placement of generic fiberglass paving mats can be found in Appendices B and C. It should be noted that the 30 mm of hot mix over the paving mat is less than the manufacturer s recommended thickness of 3 times the maximum aggregate size for the covering lift thickness. The RAC-G used a ½ inch maximum size aggregate so the manufacturer recommended cover thickness would have been 1.5 inches (38 mm). The material requirements for fiberglass polyester paving mats are given in Section 88 Engineering Mats of the Standard Specifications and the special provisions in the Innovative Materials contract 02-1C8204. These requirements state that the mat shall be non-woven, heat treated on at least one side, manufactured with fiberglass combined with polyester, polypropylene or polypropylene-nylon material with the properties shown in Table 4. 10

16 Table 4. Physical Properties of fiberglass polyester paving mat Property Test Method Units Minimum Average Roll Value (MARV) Mass per unit area ASTM D5261 g/m 2 (oz/yd 2 ) 125 (3.69) Tensile Strength, MD ASTM D5035 N/50 mm (lb/2 in) 200 (45) Tensile Strength, CD ASTM D5035 N/50 mm (lb/2 in) 200 (45) Elongation at maximum load, MD ASTM D5035 % <5 Elongation at maximum load, CD ASTM D5035 % <5 Melting Point ASTM D276 o C ( o F) >250 (>446) Section 1 with the Paving mat interlayer exhibited some moderate severity reflective transverse cracks on the shoulder; however the plans do not reflect the use of any type of inner layers on the shoulders. In the traveled lanes the wheel path showed very slight wear, most likely due to tire chains. There was some very minor large aggregate raveling on the surface of the RAC-G overlay. Figure 12 shows the condition of this section one year after placement. Existing Condition Highway 36 East Of Chester PM 14.0 to 15.0 Paving Mat + 30 mm RAC-G After 1 Year Figure 12. Section 1 with Paving Mat Interlayer before mat was placed and 1 year after construction. 11

17 SECTION 2 - POLYMER MODIFIED EMULSION (PME) INTERLAYER Figure 13 shows the condition of this section of roadway prior to the placement of the PME interlayer. In order to place seal coats on pavement in such poor condition, a stiff PG 70-10, ¼ minus (4.75 mm minus) hot mix asphalt (HMA) leveling course was placed first. EB 36 LANE 1 PM SECTION AFTER LEVELING COURSE 02-1C8201 PLU /18.4 Figure 13. Section 2 before and after leveling course. The authors want to recognize that the contractor elected to use a Materials Transfer Device (MTD) for both the leveling course and the placement of the rubberized asphalt concrete (RAC-G). This level of commitment by the contractor to the placement of a uniform thin surface resulted in a high quality surface on which to place the seal coats (photos, Appendix A). While MTD s are not typically used for interlayers, this should be considered an important part of any future interlayer placement. The PME chip seal interlayer consisted of spraying the PMCRS-2h followed immediately by spreading the screenings. Requirements for the PMCRS-2h binder residue are shown in Table 5. The aggregate screenings were a hard, crushed aggregate (Table 6). Figure 14 documents the PME chip seal interlayer before the RAC-G was placed and after 1 year of traffic and weather. The wheel paths showed very slight wear, most likely due to tire chain interaction. There is limited low level transverse cracking after 1 year. Table 5. Properties of emulsion residue after evaporation. Specification Requirements Test Method Test Method Material Properties Penetration, 15 o C, 200 grams, 60 sec AASHTO T 49 6 dmm, minimum Elastic Recovery AASHTO T 301 (report only) Polymer Content, % mass Shall not apply Ring and Ball Softening Point on Residue AASHTO T o C, minimum 12

18 Table 6. Caltrans screening requirements for medium 9.5 mm maximum size aggregate. Screening Specification Sieve Size, mm 19.0 mm mm mm mm mm mm mm mm 0-2 Percent Passing, % Figure 14. Typical condition of PME interlayer before, during, and 1 year after construction. 13

19 SECTION 3 ASPHALT RUBBER (AR) CHIP SEAL INTERLAYER Materials Requirements for Asphalt Rubber Seal Coat are defined in Section A Certificate of Compliance as defined by the Certification Program for Suppliers of Asphalt (Caltrans 2006) is required for suppliers of asphalt rubber product. The contractor is also required to submit a Certificate of Compliance for each truck load of crumb rubber modifier (CRM) used to produce the asphalt rubber binder. The asphalt rubber binder is a blend of paving grade asphalt cement, asphalt modifier, and crumb rubber modifier (CRM) from both scrap passenger car and high natural rubber content (i.e., truck tires). Paving grade asphalt cement is specified as nonpolymer modified performance graded (PG) asphalt that meets the requirements shown in Table 7. The PG asphalts which overlay these upper ranges may be approved by the Project Engineer. Table 7. Upper PG temperature requirements for unmodified paving grade asphalt cement. Caltrans Range Average 7 Day Maximum Pavement Design Temperature Minimum Pavement Design Temperature Range A Below 62 o C Range B Between 62 and 68 o C (exclusive) Not Specified Range C Greater than 68 o C The asphalt modifier is a resinous, high flash point aromatic hydrocarbon compound added to the paving grade asphalt at between 2.0 and 6.0% by mass of paving grade asphalt. The actual percent for a particular blend should be made based on the recommendation of the asphalt-rubber binder supplier. The physical property requirements for the asphalt modifier are shown in Table 8. Table 8. Requirements for asphalt modifiers used in asphalt rubber blends. Test Parameter ASTM Designation for Specification Requirement Test Method Viscosity, m 2 /s (10-10 ) at 100 o C D (+/- 3) Flash Point, Cleveland Open Cup, o C D minimum Molecular Analysis Asphaltenes, % by mass D maximum Aromatics, % of mass D minimum The CRM specification requires steel and fiber separation is accomplished using a cryogenic process so that no more than 0.01% wire and no more than 0.05% mat, both by mass of CRM. After cryogenic separation, the CRM is ground at ambient temperature to achieve the gradations shown in Table 9. The maximum length of any single CRM particle is limited to 4.75 mm. The CRM needs to be dry so that the material will flow freely and not foam when added to the heated paving grade asphalt. A maximum of 3% of calcium 14

20 carbonate or talc by mass of CRM can be added to help the flow characteristics of the CRM. Table 9. Material requirements for scrap tire and high natural rubber CRM. Specification Requirements Rubber Type Sieve Size, mm Gradation Requirements Operating Range Contract Compliance Scrap Tire CRM ASTM D297 Minimum Maximum Acetone Extract Ash Content Carbon Black Content Rubber Hydrocarbon Natural Rubber Content Specification Requirements Sieve Size, mm Gradation Requirements Operating Range Contract Compliance High Natural Rubber CRM ASTM D297 Minimum Maximum Acetone Extract Rubber Hydrocarbon Natural Rubber Content The blended asphalt rubber binder is 79% (+/- 1%) of combined paving grade asphalt cement and asphalt modifier and 21% (+/- 1%) CRM, where the CRM is made up from 76% (+/-2%) scrap tire rubber and 24% (+/-2%) high natural rubber. The CRM is added the paving grade binder at a temperature of between 190 and 226 o C, reacted for at least 45 minutes at temperatures between 190 and 218 o C but not more than 4 hours. The asphalt rubber binder will have properties shown in Table 10. Table 10.Required blended asphalt rubber properties. Test Parameter ASTM Test Blended Asphalt Rubber Binder Method Minimum Maximum Minimum Maximum Cone Penetration, 25 o C, dmm D Resilience, 25 o C, % Rebound D Field Softening Point, o C D Viscosity, 190 o C, Pa-s(x 10-3 ) Hand Held Haake 1,500 2,500 1,500 2,500 Table 11 shows the two different gradations which can be used for AR chip seals. The requirements for the chips are also given in this table. 15

21 Table 11. Caltrans screening requirements for asphalt rubber chip seals (hot applied) mm 12.5 Coarse Medium-Coarse Sieve Size, mm Percent Passing, % 19.0 mm mm mm mm mm mm mm mm LA Abrasion, 500 Rev., % Loss 25 Max. Film Stripping 25 Max. Cleanliness Value 84 Min. Durability (Dc) 52 Min. Two or More Fractured Faces, % 90% Min. Pre-Coated Aggregate Heated 127 to 175 o C then pre-coated with 0.7 to 1.0% paving grade binder No re-heating of coated chips is allowed. AR Interlayer Test Sections Figure 15 shows the structural section for this section of the roadway. This section is slightly thicker than the sections either before or after this portion of the roadway. Figure 16 shows the AR chip seal immediately after placement and before the RAC-G was placed. After 1 year, Section 3 with the asphalt rubber chip seal interlayer displayed some slight bleeding at the beginning of the section only as with Section 2, there are a limited number of low severity transverse cracks. EB 36 LANE 1 PM C8201 PLU /18.4 WB 36 LANE 1 PM C8201 PLU /18.4 Figure 15. Typical structural section in Section 3 (AR chip interlayer). 16

22 Figure 16. AR chip seal interlayer after placement and 1 year after construction. SECTION 4 MODIFIED BINDER (MB) CHIP SEAL INTERLAYER Figure 17 shows the typical structural layer for Section 4. There was some large aggregate raveling throughout the section. Near the end of the section the surface showed some bleeding, and it was noted that ruts with the depth of 1/8 inch or less using a four foot level existed. Figure 18 shows the interlayer immediately after placement and the test section 1 year after construction. EB 36 LANE 1 PM EB 36 LANE 1 PM C8201 PLU / C8201 PLU /18.4 Figure 17. Typical digout repairs prior to leveling course and typical structural thickness. 17

23 MB Immediately After Placement MB After 1 Year Highway 36 East Of Chester PM 17.3 to Figure 18. MB chip seal interlayer immediately and 1 year after construction. RAC-G MIX The rubberized asphalt concrete, gap graded, uses the asphalt rubber binder defined in the previous section at between 7% and 9% binder by dry weight of aggregate. The aggregate properties required by the specification are shown in Table 12. Table 12. Caltrans RAC-G requirements for aggregates Sieve Size, mm 19.0 mm mm mm mm mm mm mm mm 2 7 LA Abrasion, 500 Rev., % Loss 25 Durability Index (CT 229) Fine Agg (Df), Max Coarse Agg (Dc), Max Surface Abrasion (CT 360), Max 0.4 g/cm 2 Two or More Fractured Faces, % 90 18

24 SHOULDERS Unfortunately the test sections do not have a consistent paved cross-section. Sections 1 and 2 have approximately 6-ft wide paved shoulders on both sides of the roadway. The shoulders are much narrower, roughly 2.5-ft on each side in the roadway, in Sections 3. Section 4 does not have any paved shoulders. The effects of the lack of lateral support and missing protection from water intrusion in the pavement structure that exists when paved shoulders are narrow or missing must be taken into account when the quality of the interlayers are compared. SUMMARY The following conclusions can be made 1 year after construction of three interlayer systems: All four of the interlayer systems used in these test sections are performing well. There is no evidence of the severe pavement distresses in the old pavement in the new surface. The section with only the polypropylene staple fiber is showing a slightly higher severity in transverse cracking, although it is too early in the life of the test sections to determine significant differences between the test sections. All other sections are performing well with little to no cracking. The cracking that has developed is intermittent and rarely has cracked across the full width of the travelway. LESSONS LEARNED A number of lessons can be learned from the construction of these test sections: Formal mapping of the type and extent of each test section should be developed prior to the placement of test sections. This will allow researchers to classify cracking as top down due to material properties of the new surface, or from the bottom up (i.e., reflective cracking). One person should be designated to collect all of the material property information from either the material supplier. Both photographic and written logs of the surface preparation, test section construction, and weather conditions should be kept. It would be best if this was done by the person collecting the material property. The uniformity of the leveling course placed using a materials transfer device and a paving screed provide a uniform surface prior to interlayers. 19

25 RECOMMENDATIONS Conduct yearly pavement condition surveys with crack mapping so that the life expectancy of each type of interlayer can be assessed. Factors that need to be considered in any assessment of performance are: The original pavement condition differs between the interlayer test sections. The paving mat interlayer section was placed on an existing pavement with an older, somewhat aged, leveling course. The other interlayer systems were placed on a fresh leveling course. The MB chip seal section had the most digouts covered by the leveling course, followed by the interlayer system. Differences between the test sections may be linked to the different conditions of the pavement on which they were placed. Perform follow-up FWD testing for comparison of pre- and post-interlayer construction structural differences. It is hoped that any reduction in moisture in the underlying layers will be seen as an increase in the pavement layer stiffness. It is also possible that any spreading of the applied load by the fabric interlayer may be seen as lower deflections in the lower layers. The FWD testing should be conducted at the same time of year as the original testing to minimize seasonal influence on the calculated layer stiffness. REFERENCES Caltrans 1 (2006) Caltrans 2 (2006) Caltrans Contract No. 02-1C8204 MTAG Chapter 12 Draft

26 APPENDIX A Innovation Pre-Proposal, Proposal, and Final Report Format

27 Objective Innovation Pre-Proposal, Proposal and Final Report Format The innovative project is located in Plumas County on state route 36 approximately 5 miles east of the City of Chester. The project will compare various non-standard and standard seal coat specifications by applying the specified products then overlaying with rubberized paving grade asphalt concrete. The objective is to determine the cost effectiveness and performance characteristics of first sealing the pavement then overlaying with rubberized asphalt concrete. This strategy is generally referred to as an interlayer. The cost effectiveness will be measured using a life cycle cost analysis based on field performance gained using interlayers compared to typical life cycle cost of pavements placed without interlayers. Performance characteristics will include resistance to reflective cracking, resistance to rutting, and long term performance. These applications are consistence with maintenance efforts to maintain travelways currently in a poor state of repair. The success of this project should assist the Division of Maintenance by providing an additional project that correlates added service life gained by placing an interlayer that seals the existing pavement and absorbs applied stresses. Using a life cycle cost analysis this strategy should provide a less costly, longer lasting pavement maintenance solutions where major rehabilitation are low priority and unlikely for program funding. The following information will provide details of the project. Background There have been a few projects built in California using both 2-layer systems also referred to as interlayer systems. The last project using a 2-layer strategy was sponsored by the near the California Integrated Waste Management Board (Esparto site) constructed in This Esparto site has provided a clear indicator that by first placing a flexible interlayer that seals the pavement, then overlaying with a thin asphalt concrete can extend the service life of typical maintenance strategies. The Esparto site continues to perform well after 13 years. Caltrans has used interlayers as an integral part of crack seat and overlay rehabilitation strategies. The interlayer served as a stress absorbing membrane interlayer (SAMI) designed to seal and provides a high resistance to reflective cracking. Typically these SAMI s have been in the form of a rubberized chip seal or a non-woven polyester mat. This project should provide additional documentation of the effectiveness of 2-layer systems

28 Elements of the Innovation Pre-proposal Title Plumas-36 2-Layer pavement maintenance test section Contact information Lance Brown, (530) Matt Gowan Description This project will place and compare a polyester fiberglass pavement mat and three different chip seal/interlayer strategies on a section of distressed pavement. This location was selected because it will provide a consistent before pavement condition for all four strategies. Benefits This project will compare the benefit of additional service life gained by first placing a flexible interlayer material then overlaying with a rubberized asphalt concrete. The strategies used should provide exceptional resistance to reflective cracking. This project should provide pavement managers alternative strategies and measure the performance characteristic of each interlayer material. In addition this will allow a comparison of the effectiveness of overlay only verses the use of a flexible interlayer. This project will effectively maintain a severely distressed pavement in need of rehabilitation at minimal cost and delay. This project will also provide a correlation of other similar interlayer test sites. Selection criteria The pre-project condition of the pavement in this test section is poor. The pavement exhibits moderate to severe alligator cracking, transverse cracking, longitudinal cracking, some wheel rutting, high oxidation and has some areas repaired by grinder digouts. This location will allow the testing of four different maintenance strategies on a poor condition pavement. Specifications Specifications used in this project are a combination of standard and non-standard special provisions (SSP and NSSP). The NSSP used in this project include: Modified Binder Asphalt and Fiberglass polyester paving mat. The SSP used in this project include: Rubberized asphalt Concrete (Type-G) Seal coal (Polymer Modified) Asphalt Rubber Seal Coat - 2 -

29 Elements of the Innovation Proposal Note that items 1-7 of the pre-proposal will be included as the first six items of the full proposal. Project Location PLU /18.4(R22.5/R29.6 kp). This test section will be placed on both the east bound and westbound lanes throughout the test section. Test section markers will be placed at the beginning and end points for each strategy. They will be placed 20 ft (6M) from the edge of pavement in the east bound direction. Estimated Costs The engineer s estimate for this project is $901,000. Potential problems, impacts and remedies This project is a relatively short section with four strategies being tested. As the test is being conducted, any pavement failures will have to be remediated to allow for the smooth flow of traffic through the project area. Warranties Based on the goals of this test section, a warranty is not applicable. The project does not meet current warranty guidelines. Evaluation Plan The evaluation plan will be based on preconstruction data collected, data collected during construction and data collected after construction as described herein. Preconstruction The data collected prior to construction will include, deflection study report, traffic evaluation and counts, 100% pavement condition survey that reflects a quantification of all visual distresses in the pavement and rut data. Coring will be taken to determine type or types of in-situ asphalt concrete and base. In addition a detailed video will be collected of the entire project limit. The video will contain station marking for reference points. Construction A record will be kept per requirements of the contract specifications that include, source of base stock oils, testing of all modified binders, actual spread rates of oil and aggregates, mix design of rubberized asphalt concrete (void, stability, and oil). The testing will include all modified binder viscosity, torsion recovery testing, softening points, Cone penetration, LA rattler, cleanliness value, actual gradations used for screening, and durability. The asphalt concrete will have time of placement, temperature of placement, relative compaction recorded. Post Construction - 3 -

30 The post construction plan will be to monitor the visual distress and rutting present using an annual 100% pavement condition survey and traffic study of change to classifications. A final report will be prepared at year 5 that determines the effectiveness with respect to Distress with time and Distress with equivalent ESAL loading. The report will include conclusions and recommendation based on data collected. Elements of the Innovation Final Report Note that items 1-15 of the proposal will be included as the first part of the report. Evaluation Results Test results prior, during and after construction will be presented. Performance Analysis Results will be analyzed and the performance will be compared to current Caltrans practices. Life-Cycle Costs The performance and project costs will be examined for life-cycle costs. It is recommended that the life-cycle costs be compared to current Caltrans practice using the appropriate design lives and discount factors. Future anticipated production costs should be discussed here, also. Conclusions Discuss how the innovation compares to current Caltrans practice. Recommendations Successful innovations should be directed to the appropriate specification committee. Recommendations for improving innovations that failed (via the definition set up in step 13) should be described here

31 APPENDIX B Fiberglass/Polyester Paving Mat

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39 APPENDIX C Asphalt Rubber NSSP

40 Page 1 of ASPHALT-RUBBER SEAL COAT Asphalt-rubber seal coat shall consist of an application of asphalt-rubber binder and screenings precoated with paving asphalt. Asphalt-rubber seal coat shall conform to the provisions specified for seal coats in Section 37-1, "Seal Coats," of the Standard Specifications and to these special provisions. GENERAL Attention is directed to "Order of Work" and "Damage Claims" of these special provisions regarding placement of asphalt-rubber seal coat. The Contractor shall furnish a Certificate of Compliance to the Engineer in conformance with the provisions in Section , "Certificates of Compliance," of the Standard Specifications for each material used in the asphalt-rubber binder and the asphalt-rubber binder mixture. When requested by the Engineer, the Contractor shall also submit samples with the Certificates of Compliance. The Contractor shall provide the Engineer a Material Safety Data Sheet (MSDS) for each of the constituent components of the asphalt-rubber binder and for the completed mixture of the asphalt-rubber binder. The Contractor shall provide a Certificate of Compliance for each truck load of crumb rubber modifier (CRM), paving asphalt, and asphalt modifier delivered to the project. The Quality Control Program used by the manufacturer of each ingredient shall include a sampling and testing frequency as shown below: A. CRM shall be tested except for the grading requirement, at least once for every 225 tonnes with a minimum of once per project. CRM shall be tested for grading for every truck load delivered to the project. B. Paving asphalt shall be tested at least once for every 180 tonnes of production with a minimum of once per project. C. Asphalt modifier shall be tested at least once for every 23 tonnes of production with a minimum of once per project. D. A copy of the laboratory test results for the test parameters specified in these special provisions for CRM, paving asphalt, and asphalt modifier shall be submitted to the Engineer with the Certificate of Compliance for each truck load of individual material delivered to the project. Certified volume or mass slips shall be delivered to the Engineer for materials supplied. PAVING ASPHALT Paving asphalt to be used in the asphalt-rubber binder shall be Grade PG and shall conform to the provisions in Section 92, "Asphalts," of the Standard Specifications and these special provisions. Paving asphalt Grade PG shall not be polymer modified. The paving asphalt for use in asphalt-rubber binder shall be modified with an asphalt modifier

41 ASPHALT MODIFIER The asphalt modifier shall be a resinous, high flash point, aromatic hydrocarbon compound and shall conform to the following requirements: ASPHALT MODIFIER Test Parameter ASTM Designation Requirement Viscosity, m 2 /s (10-6 ) at 100 C D 445 X ± 3* Flash Point, CL.O.C. C D min. Molecular Analysis Asphaltenes, percent by mass D max. Aromatics, percent by mass D min. * The symbol "X" is the viscosity of the asphalt modifier the Contractor proposes to furnish. The value "X" which the Contractor proposes shall be between the limits 19 and 36 and shall be submitted in writing to the Engineer. Any proposed change, requested by the Contractor, in the value "X" shall require a new asphalt-rubber binder design. The asphalt modifier shall be proportionately added to the paving asphalt at the production site where the asphalt-rubber binder is blended and reacted. Asphalt modifier shall be added at an amount of 2.5 percent to 6.0 percent by mass of the paving asphalt based on the recommendation of the asphalt-rubber binder supplier. The paving asphalt shall be at a temperature of not less than 190 C or more than 226 C when the asphalt modifier is added. If the asphalt modifier is combined with the paving asphalt, before being blended with the CRM, the combined paving asphalt and asphalt modifier shall be mixed by circulation for a period of not less than 20 minutes. This premixing of asphalt modifier and paving asphalt will not be required when all ingredients of the asphaltrubber binder are proportioned and mixed simultaneously. Asphalt modifier and paving asphalt shall be measured for proportioning with meters conforming to the provisions in Section , "Measurement of Quantities," of the Standard Specifications. CRUMB RUBBER MODIFIER (CRM) Crumb rubber modifier (CRM) shall consist of a combination of scrap tire CRM and high natural CRM. The scrap tire CRM shall consist of ground or granulated rubber derived from any combination of automobile tires, truck tires or tire buffings. The high natural CRM shall consist of ground or granulated rubber derived from materials that utilize high natural rubber sources. Steel and fiber separation shall be accomplished by any method. Cryogenic separation, if utilized, shall be performed separately from and prior to grinding or granulating. CRM shall be ground or granulated at ambient temperature. Cryogenically produced CRM particles that pass through the grinder or granulator without being ground or granulated, respectively, shall not be used. CRM shall not contain more than 0.01-percent wire (by mass of CRM) and shall be free of other contaminants, except fabric. Fabric shall not exceed 0.05-percent by mass of CRM. The test and method for determining the percent by mass of wire and fabric is available at the Transportation Laboratory, Office of Pavement Consulting Services, Sacramento, California, Telephone (916) , and will be furnished to interested persons upon request. A certificate of compliance certifying these percentages shall be - 2 -

42 furnished to the Engineer in conformance with the provisions in Section , "Certificates of Compliance," of the Standard Specifications. The length of an individual CRM particle shall not exceed 4.75 mm. The CRM shall be sufficiently dry so that the CRM will be free flowing and will not produce foaming when combined with the blended paving asphalt and asphalt modifier mixture. Calcium carbonate or talc may be added at a maximum amount of 3 percent by mass of CRM to prevent CRM particles from sticking together. The CRM shall have a specific gravity of between 1.1 and 1.2 as determined by California Test 208. Scrap tire CRM and high natural CRM shall be delivered to the production site in separate bags and shall be sampled and tested separately. CRM material shall conform to the following requirements as determined by ASTM Designation: D 297: SCRAP TIRE CRM HIGH NATURAL CRM Percent Percent Test Parameter Minimum Maximum Minimum Maximum Acetone Extract Rubber Hydrocarbon Natural Rubber content Carbon Black Content Ash Content 8.0 The CRM for asphalt-rubber binder shall conform to the gradations specified below when tested in conformance with the requirements in ASTM Designation: C 136, except as follows: A. Split or quarter 100 g ± 5 g from the CRM sample and dry to a constant mass at a temperature of not less than 57 C nor more than 63 C and record the dry sample mass. Place the CRM sample and 5.0 g of talc in a 0.5-L jar. Seal the jar, then shake the jar by hand for a minimum of one minute to mix the CRM and the talc. Continue shaking or open the jar and stir until particle agglomerates and clumps are broken and the talc is uniformly mixed. B. Place one rubber ball on each sieve. Each ball shall have a mass of 8.5 g ± 0.5 g, have a diameter of 24.5 mm ± 0.5 mm, and shall have a Shore Durometer "A" hardness of 50 ± 5 in conformance with the requirements in ASTM Designation: D After sieving the combined material for 10 minutes ±1 minute, disassemble the sieves. Material adhering to the bottom of a sieve shall be brushed into the next finer sieve. Weigh and record the mass of the material retained on the 2.36-mm sieve and leave this material (do not discard) on the scale or balance. Observed fabric balls shall remain on the scale or balance and shall be placed together on the side of the scale or balance to prevent the fabric balls from being covered or disturbed when placing the material from finer sieves onto the scale or balance. The material retained on the next finer sieve (2.00-mm sieve) shall be added to the scale or balance. Weigh and record that mass as the accumulative mass retained on that sieve (2.00-mm sieve). Continue weighing and recording the accumulated masses retained on the remaining sieves until the accumulated mass retained in the pan has been determined. Prior to discarding the CRM sample, separately weigh and record the total mass of fabric balls in the sample

43 C. Determine the mass of material passing the 75-µm sieve (or mass retained in the pan) by subtracting the accumulated mass retained on the 75-µm sieve from the accumulated mass retained in the pan. If the material passing the 75-µm sieve (or mass retained in the pan) has a mass of 5 g or less, cross out the recorded number for the accumulated mass retained in the pan and copy the number recorded for the accumulated mass retained on the 75-µm sieve and record that number (next to the crossed out number) as the accumulated mass retained in the pan. If the material passing the 75-µm sieve (or mass retained in the pan) has a mass greater than 5 g, cross out the recorded number for the accumulated mass retained in the pan, subtract 5 g from that number and record the difference next to the crossed out number. The adjustment to the accumulated mass retained in the pan is made to account for the 5 g of talc added to the sample. For calculation purposes, the adjusted total sample mass is the same as the adjusted accumulated mass retained in the pan. Determine the percent passing based on the adjusted total sample mass and record to the nearest 0.1 percent: SCRAP TIRE CRM PERCENTAGE PASSING Sieve Sizes Gradation Requirements Operating Range Contract Compliance 2.36-mm mm mm m m m m HIGH NATURAL CRM PERCENTAGE PASSING Sieve Sizes Gradation Requirements Operating Range Contract Compliance 2.36-mm 2.00-mm mm m m m m OPERATING RANGE - If the contractor falls outside the operating range for the scrap tire CRM, but stays within the contract compliance limits, the asphalt rubber seal coat represented by the test shall be removed. However, if requested in writing by the contractor and approved by the engineer, the asphalt rubber seal coat may remain in place and the contractor shall pay to the state $ per each test result falling outside the operating range. Each single grading test shall represent 4500 kg of the scrap tire CRM or the amount used in that one day s production, whichever is less. If the contractor falls outside the operating range for the high natural CRM, but stays within the contract compliance limits the asphalt rubber seal coat represented by the test shall be removed. However, if requested in writing by the contractor and approved by the engineer, the asphalt rubber seal coat may remain in place and the contractor shall pay to the state - 4 -