DengXin Cheng & Gary Hicks
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Presentation by DengXin Cheng and Gary Hicks of California State University, Chico Pavement Preservation Center on the topic of pavement preservation delivered at the CalAPA Fall Asphalt Pavement Conference Oct. 24, 2013 in Sacramento, Calif.
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DengXin Cheng & Gary Hicks
- 1. Stretching Pavement Maintenance Dollars Through Pavement Preservation By R. Gary Hicks and Ding Cheng CP2 Center, CSU, Chico for the Fall Asphalt Pavement Conference October 24, 2013
- 2. Overview of Presentation • Types of Treatments – – Materials Used Design & Construction Considerations – Causes of problems • Factors Affecting Performance • Strategy Selection Process Most of this work has been supported by Caltrans 2
- 4. Condition Cost Effectiveness Pavement Preservation $1-3 for preventive maintenance here Costs $1020 or more when it’s done as rehab Time 4
- 5. Types of Preservation Treatments • Fog and Rejuvenating Seals • Chip Seals • Slurry Seals • Microsurfacing • Cape Seals • Bonded Wearing Courses • Thin HMA overlays • CIR and HIR 5
- 6. Fog and Rejuvenating Seals • Purpose- enriches dry pavement surfaces, reduces raveling, and locks in chips on chip seals • Materials- generally diluted asphalt emulsions or a specialty product • Design considerations- application rate a function of surface condition • Construction- applied using a distributor truck in diluted form • Expected life - 1 to 3 years or more 6
- 7. • Using excess emulsion for the existing pavement surface • Placing in wet and/or cool weather • Over or under dilution • Incompatible water for dilution 7
- 8. • Purpose- waterproof the existing surface and improve texture. Can also serve as an interlayer • Materials- application of emulsions or hot binders followed by clean aggregate • Design- application rates need to be determined • Construction-asphalt is applied followed by an application of aggregate. May be used in multiple layers • Expected life- 5-7 years or more 8
- 9. Binder Application Sweeping (before and after) Aggregate Application Rolling 9
- 10. • • • • Improper surface preparation Applying in cool and/or wet weather Using dirty rock Not accounting for new patches or flushed surfaces • Not taking traffic into account • Over spreading or under spreading binder or aggregate • Application on unsound pavements 10
- 12. • Chip seal with a polymer modified rejuvenating emulsion (PMRE) • A scrub broom is used to push the emulsion into the cracks • Rejuvenates as it seals the pavement surface 12
- 13. 13 13
- 14. The size of wave is a function of the number and severity of cracks. 14 14
- 15. Existing pavement After emulsion applied with the scrub broom 15
- 16. • Purpose- Seals minor cracks, restores surface texture, mitigates raveling • Materials- a mixture of graded aggregate, asphalt emulsion (generally polymer modified), and setting agents • Design considerations- special mix design is needed • Construction-applied using a special paver mounted on a truck • Expected life- 5 to 7 years or more if placed on sound pavements 16
- 18. Type I II III Crack Filling General Seal MediumTextured Surface Rough -Textured Surface Urban Streets Primary Highways Fine Seal Parking Lots Residential Streets Airfield Runway 18
- 19. • Improper surface preparation or placing on unsound pavements • Place in cool and/or wet weather • Not requiring a mix design or calibrating the equipment • Aggregate grading out, especially in fines content • Too much or too little additive • Improper maintenance of spreader box and drag • Adding too much water 19
- 20. Unsound Pavement Improper Surface Preparation Unsound Pavement Improper Mix design 20
- 21. • Purpose- seal the surface, fill wheel ruts and minor surface irregularities, and can be placed at night • Materials- a mixture of graded aggregates, polymer modified emulsion, and set additives • Design considerations- requires a mix design to determine the proportion of components • Construction- applied using a special truck mounted mixing/paving machine. For long straight jobs a continuous machine is recommended • Expected life-last 8-12 years depending on the surface it is applied too 21
- 23. Interstates Placed at Night Arterials Quick Traffic Cool Climates 23
- 24. • Improper surface preparation or placing on badly cracked pavements • No mix design • Construction in wet weather • Truck mounted equipment placing improper joints • Too much hand work • Too much overlap on joints • Too much water in the mix causing segregation 24
- 26. • Purpose- seal the surface and provide a smooth hard wearing surface • Materials- a chip seal followed by a slurry seal • Design considerations- mix designs for both products • Construction- application of a chip seal followed by a slurry seal • Expected life- 8-12 years or more 26
- 27. Slurry Chip Seal Followed by a Slurry 27
- 28. Chip Seal Slurry Seal Finished Surface 28
- 29. • • • Improper surface preparation No mix designs Applying in cool and/or wet weather • Over application of binder in either course • Using conventional chip seal or polymer modified chip seals over cracked surfaces. 29
- 30. Thin Bonded Overlays • Application of polymer modified binder immediately followed by a thin hot mix overlay • Total thickness has been about 25 mm • Applied with a spray paver 30
- 31. Thin HMA Overlays • Types – Conventional – Polymer modified asphalt – Asphalt rubber – Terminal Blend • Thickness 1-1.5 inch • Used with warm mix additives 31
- 32. Factors Affecting the Performance of Pavement Preservation Treatments • Existing pavement condition • Construction process and workmanship • Materials quality and selection • Climate and Traffic 32
- 33. Pretreatment Pavement Condition Fair Poor 36% 64% Standard Deviation 18% 18% Materials Selection and Quality Marginal Poor 36% 57% 22% 20% Construction and Workmanship Marginal Poor 45% 61% 21% 21% Mix and Structural Design Marginal Poor 35% 57% 19% 20% Medium Poor 22% 45% 22% 25% Marginal Poor 33% 50% 24% 24% Treatment Life Reduction Percentage, % Average Traffic Level Climate during and immediately after construction 33
- 34. 34
- 35. Strategy Selection Process • Assess Pavement Conditions • Determine Feasible Treatment Options • Analyze and Compare Feasible Options 35
- 36. User Interface – Main Page 36
- 37. •Treatment Life •Treatment Cost •Interest Rate Equivalent Annual Cost 37
- 38. Advantage of the Preliminary Developed Expert System • Uses Caltrans MTAG existing decision matrix • Can deal with more complex scenarios • Knowledge is retained to the system • New treatments can be added http://ceresearch.ecst.csuchico.edu/TreatmentSelection2.0/V 38
- 39. • Types of Surface Treatments – – – Design and construction considerations Expected performance Causes of problems • Factors Affecting the Performance of Preservation Treatments-FHWA study • Strategy Selection Process Using Life Cycle Cost 39
Editor's Notes
- {"38":"Uses Caltrans MTAG existing decision matrix as first step to narrow down answers\nCan deal with more complex scenarios than common decision tree or decision matrix\nKnowledge is retained to the system\nNew treatments can be added to the system fairly easy without overhaul the whole structure (tree or matrix)\n","12":"Base asphalt\nSolvent-free rejuvenating agent\nHigh quality emulsifier\nTough Polymer\nPASS Components are sourced from the best in the industry. The polymer has been specifically formulated for PASS. is unique in that it is the only chip retention emulsion with a rejuvenating agent added. \n","14":"There are three factors that need to be addressed when using the Boom:\nEnough emulsion to retain the chips.\nEnough Emulsion in the wave to fill the cracks. This a function of crack intensity\nYou do not want emulsion to flow outside the broom head. In this case re reduced the spray width and compensated by rate adjustment.\n","4":"Changed wording to add “corrective maintenance”\nEFFECTIVE PREVENTIVE MAINTENANCE\nMany states as well as the federal highway administration have found that doing preventive maintenance is 3 to 10 times more cost effective than a do nothing strategy.\n"}