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1-2-3’s of PGAC

This presentation discusses the critical conditions during the construction and service of asphalt, including mixing, spreading, compacting, and the issues of plastic deformation, fatigue cracking, and thermal cracking. It also covers the specifications of paving asphalts and how they play a role in predicting service performance and excluding poor performing products.

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1-2-3’s of PGAC

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  1. 1-2-3’s of PGAC Calgary Presentation August 14, 2006

  2. Properties of Asphalt • Critical conditions during construction and service • Construction: • mixing • spreading  appropriate viscosity • compacting • Service: • plastic deformation (rutting) • fatigue cracking • thermal cracking

  3. Specifications of Paving Asphalts • The role of specifications: • specify properties that directly reflect asphalt behaviour • express these properties in physical units • provide information from which the service performance can be predicted • establish limits for those properties to exclude poor performing products

  4. Canadian Federal Specification Penetration at 25°C [dmm]

  5. Superpave PG Specification • Superpave specification attempts to measure properties that are directly related to pavement field performance PERFORMANCE PROPERTY TEST EQUIPMENT Handling Pump Rotational Viscometer Flow Rutting Permanent Deformation Dynamic Shear Rheometer Fatigue Cracking Structural Cracking Thermal Cracking Bending Beam Rheometer Direct Tension Tester Low Temp Cracking

  6. Superpave Asphalt Binder Specification PG 58 - 31 Min pavement temperature Performance Grade Average 7-day Max pavement temperature

  7. Performance Grade Specifications • PGAC specifications explicitly quantify the binder performance at actual in-service pavement temperatures • PGAC specifications explicitly consider the in-service aging characteristics of the binder once it is placed on the road • PGAC specifications contain formal protocols for addressing in-service traffic conditions • PGAC specifications explicitly accommodate the concept of reliability • PGAC specifications can be used to specify (high performance) modified binder systems

  8. How the PG Spec Works 58 64 CEC Spec Requirement Remains Constant Avg 7-day Max, oC PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82 1-day Min, oC -34 -40 -46 -10 -16 -22 -28 -34 -40 -46 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -10 -16 -22 -28 -34 ORIGINAL > 230 oC (Flash Point) FP <3Pa.s@135 oC (Rotational Viscosity) RV (Dynamic Shear Rheometer) DSR G*/sin  > 1.00 kPa 46 52 58 64 70 76 82 (ROLLING THIN FILM OVEN) RTFO Mass Loss < 1.00 % (Dynamic Shear Rheometer) DSR G*/sin  > 2.20 kPa 46 52 58 64 70 76 82 (PRESSURE AGING VESSEL) PAV 20 Hours, 2.07 MPa 90 90 100 100 100 (110) 100 (110) 110 (110) Test Temperature Changes (Dynamic Shear Rheometer) DSR G* sin  < 5000 kPa 28 10 7 4 25 22 19 16 13 10 7 25 22 19 16 13 31 28 25 22 19 16 34 31 28 25 22 19 37 34 31 28 25 40 37 34 31 ( Bending Beam Rheometer) BBR “S” Stiffness & “m”- value S < 300 MPa m > 0.300 -24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24 Report Value (Bending Beam Rheometer) BBR Physical Hardening > 1.00 % (Direct Tension) DT -24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

  9. Permanent Deformation CEC Avg 7-day Max, oC PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82 1-day Min, oC -34 -40 -46 -10 -16 -22 -28 -34 -40 -46 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -10 -16 -22 -28 -34 ORIGINAL > 230 oC (Flash Point) FP <3Pa.s@135 oC (Rotational Viscosity) RV (Dynamic Shear Rheometer) DSR G*/sin  > 1.00 kPa 46 52 58 64 70 76 82 (ROLLING THIN FILM OVEN) RTFO Mass Loss < 1.00 % • Unaged • RTFO Aged (Dynamic Shear Rheometer) DSR G*/sin  > 2.20 kPa 46 52 58 64 70 76 82 (PRESSURE AGING VESSEL) PAV 20 Hours, 2.07 MPa 90 90 100 100 100 (110) 100 (110) 110 (110) (Dynamic Shear Rheometer) DSR G* sin  < 5000 kPa 28 10 7 4 25 22 19 16 13 10 7 25 22 19 16 13 31 28 25 22 19 16 34 31 28 25 22 19 37 34 31 28 25 40 37 34 31 ( Bending Beam Rheometer) BBR “S” Stiffness & “m”- value S < 300 MPa m > 0.300 -24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24 Report Value (Bending Beam Rheometer) BBR Physical Hardening > 1.00 % (Direct Tension) DT -24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

  10. Permanent Deformation Question: Why a minimum G*/sin d to address rutting Answer: We want a stiff, elastic binder to contribute to mix rutting resistance How: By increasing G* or decreasing d

  11. Fatigue Cracking CEC Avg 7-day Max, oC PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82 1-day Min, oC -34 -40 -46 -10 -16 -22 -28 -34 -40 -46 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -10 -16 -22 -28 -34 ORIGINAL > 230 oC (Flash Point) FP <3Pa.s@135 oC (Rotational Viscosity) RV (Dynamic Shear Rheometer) DSR G*/sin  > 1.00 kPa 46 52 58 64 70 76 82 (ROLLING THIN FILM OVEN) RTFO Mass Loss < 1.00 % (Dynamic Shear Rheometer) DSR G*/sin  > 2.20 kPa 46 52 58 64 70 76 82 (PRESSURE AGING VESSEL) PAV 20 Hours, 2.07 MPa 90 90 100 100 100 (110) 100 (110) 110 (110) PAV Aged (Dynamic Shear Rheometer) DSR G* sin  < 5000 kPa 28 10 7 4 25 22 19 16 13 10 7 25 22 19 16 13 31 28 25 22 19 16 34 31 28 25 22 19 37 34 31 28 25 40 37 34 31 ( Bending Beam Rheometer) BBR “S” Stiffness & “m”- value S < 300 MPa m > 0.300 -24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24 Report Value (Bending Beam Rheometer) BBR Physical Hardening > 1.00 % (Direct Tension) DT -24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

  12. Fatigue Cracking Question: Why a maximum G* sin d to address fatigue? Answer: We want a soft elastic binder (to sustain many loads without cracking) How: By decreasing G* or decreasing d

  13. Low Temperature Cracking CEC Avg 7-day Max, oC PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82 1-day Min, oC -34 -40 -46 -10 -16 -22 -28 -34 -40 -46 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -10 -16 -22 -28 -34 ORIGINAL > 230 oC (Flash Point) FP <3Pa.s@135 oC (Rotational Viscosity) RV PAV Aged (Dynamic Shear Rheometer) DSR G*/sin  > 1.00 kPa 46 52 58 64 70 76 82 (ROLLING THIN FILM OVEN) RTFO Mass Loss < 1.00 % (Dynamic Shear Rheometer) DSR G*/sin  > 2.20 kPa 46 52 58 64 70 76 82 (PRESSURE AGING VESSEL) PAV 20 Hours, 2.07 MPa 90 90 100 100 100 (110) 100 (110) 110 (110) (Dynamic Shear Rheometer) DSR G* sin  < 5000 kPa PAV Aged 28 10 7 4 25 22 19 16 13 10 7 25 22 19 16 13 31 28 25 22 19 16 34 31 28 25 22 19 37 34 31 28 25 40 37 34 31 ( Bending Beam Rheometer) BBR “S” Stiffness & “m”- value S < 300 MPa m > 0.300 -24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24 Report Value (Bending Beam Rheometer) BBR Physical Hardening > 1.00 % (Direct Tension) DT -24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

  14. Low Temperature Cracking Question: Why a maximum S value and minimum m and ƒ values to address low temperature cracking? Answer: We want a soft, creep stiffness relaxing, ductile binder How: By decreasing S or increasing the m and ƒ values.

  15. Miscellaneous Spec Requirements CEC Avg 7-day Max, oC PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82 1-day Min, oC -34 -40 -46 -10 -16 -22 -28 -34 -40 -46 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -10 -16 -22 -28 -34 ORIGINAL > 230 oC (Flash Point) FP <3Pa.s@135 oC (Rotational Viscosity) RV (Dynamic Shear Rheometer) DSR G*/sin  > 1.00 kPa 46 52 58 64 70 76 82 MassLoss (ROLLING THIN FILM OVEN) RTFO Mass Loss < 1.00 % FlashPoint (Dynamic Shear Rheometer) DSR G*/sin  > 2.20 kPa 46 52 58 64 70 76 82 (PRESSURE AGING VESSEL) PAV 20 Hours, 2.07 MPa 90 90 100 100 100 (110) 100 (110) 110 (110) (Dynamic Shear Rheometer) DSR G* sin  < 5000 kPa 28 10 7 4 25 22 19 16 13 10 7 25 22 19 16 13 31 28 25 22 19 16 34 31 28 25 22 19 37 34 31 28 25 40 37 34 31 ( Bending Beam Rheometer) BBR “S” Stiffness & “m”- value S < 300 MPa m > 0.300 -24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24 Report Value (Bending Beam Rheometer) BBR Physical Hardening > 1.00 % (Direct Tension) DT -24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

  16. Performance Grade Specifications • Husky supports the use and the specification for Performance Graded Asphalt Cements (PGAC) as written in AASHTO M320-05 Table 1 (MP1) and Table 2 (MP1A). • No adjustment to spec limits (BBR S m DSR G*/sin δ values) • No additional PG + Specifications • PGAC specifications are based on the science of rheology, the study of stress and strain and not a consistency measurement such as penetration

  17. PGAC Selection Process

  18. Determining Pavement Design Temperatures • Starting with the Climatic Data • It is important for practitioners to: • look at several sites near your design location, • understand the nature of the weather data for each site, and • apply proper engineering judgment as to which data set(s) are most applicable to your specific design situation. “The best weather station may not necessarily be the closest weather station”

  19. Determining Pavement Design Temperatures • For each weather station: • the hottest seven-day period was identified and the average maximum air temperature (for this seven-day period) was computed and used to define the hot temperature design condition, and • the one-day minimum air temperature was used to define the cold temperature design condition.

  20. Determining Pavement Design Temperatures

  21. Determining Pavement Design Temperatures • Converting Climate Data into Pavement Temperatures • Most practioners in western Canada support the use of the LTPP High Pavement Temperature Model coded into LTPPBind V2.1, July 1999 • More conservative than the SHRP High Pavement Temperature model • Most practioners in western Canada support the use of the Revised Low Pavement Temperature Model in TAC Technical Brief #15, October 1998 • Superior correlation to observed field measurements at select Canadian sites

  22. Determining Pavement Design Temperatures • Converting Climate Data into Pavement Temperatures • LTPPBind 2.1 does not support the TAC model • LTPPBind 2.1 has aggressive grade bumping protocols (KMC,SHRP)

  23. Determining Pavement Design Temperatures • Specifying Reliability– Explicitly Considering Risk • Reliability is defined as the percent probability, in a single year, that the actual temperature (one-day low or seven-day average high) will not exceed the design temperature “A higher level of reliability means a lower level of risk”

  24. Determining Pavement Design Temperatures • Specifying Reliability – Explicitly Considering Risk • Level of reliability is a function of the application • Is this a major highway or low volume road? • What is the implication of a failure? • Reliability must be consistent with Owner Agency policy. • Reliability of the high temperature grade can be different for the low temperature • Husky supports a high level of reliability (99%) on the high temperature • Rutting leading to safety issues i.e. Hydroplaning • In addition to LTPP High Pvm’t Temperature model

  25. Determining Pavement Design Temperatures • Specifying Reliability – Explicitly Considering Risk • Husky supports a moderate level (90%) for low pavement temperature • Failure modes like cracking are a performance cost/ issue and therefore must be set within the context of life cycle cost considerations. • Consider using 99% reliability on the high temperature and 90% reliability for the low temperature • Then adjust your reliability thresholds to be consistent with Owner/Agency policy and suit your site specific design requirements and project economics • Provides reasonable environmental grades for most sites across western Canada

  26. Determining PGAC Environmental Grade

  27. Determining Pavement Design Grade

  28. Determining Pavement Design Temperatures Pavement PG design grade is determined by: 1) climatic statistics of the design site, 2) the pavement temperature model selected, 3) the design reliability, 4) high temperature grade bumping protocol,

  29. Determining PGAC Environmental Grade • Grade Selection Matrix-Customized for Western Canada • Husky supports the splitting of the low temperature grade into 3 C intervals • The splitting of grades allow you to spec the actual performance that has been provided by CGSB graded asphalts in western Canada (SGS and Cold Lake crudes) • PG 64-25 (80/100A) • PG 58-31 (120/150A) • PG 52-34 (200/300A) • PG 46-37 (300/400A)

  30. Determining PGAC Environmental Grade • Grade Selection Matrix-Customized for Western Canada • Husky supports the splitting of the low temperature grade into 3 C intervals • The slope of the straight run PG grading curve indicates the high temperature grade increases 1.4 C for every 1 C decrease (worsening) in the low temperature grade • Depending on the project site, modification in 3 C increments on the low temperature will save costs. May achieve the desired reliability at -37 C instead of -40 C.

  31. Determining PGAC Environmental Grade • Recommended Grade Selection Matrix-Customized for Western Canada • 16 potential grades for western Canada • Production and inventory considerations • Some grades are redundant in that the lowest quality straight run asphalt exceeds them • Some grades are too expensive to be practical • Some modified grades can be consolidated into higher grades with similar cost structures • Maximize grade availability to maximize design flexibility • Minimize grade availability to limit grade proliferation

  32. Determining PGAC Environmental Grade

  33. PGAC Calgary, Alberta

  34. PGAC Calgary, Alberta

  35. PGAC Calgary, Alberta

  36. PGAC Calgary, Alberta

  37. PGAC Calgary, Alberta

  38. PGAC Calgary, Alberta

  39. PGAC Calgary, Alberta

  40. PGAC Calgary, Alberta

  41. PGAC Calgary, Alberta

  42. PGAC Calgary, Alberta

  43. PGAC Calgary, Alberta Environmental Grade PG 58-31

  44. PGAC Calgary, Alberta • Environmental Grade PG 58-31 • PG 64-31 • Slow traffic where the average traffic speed is between 20 to 70 km/hr • Design ESAL’s over 0.3 million • PG 70-31 • Standing traffic where the average traffic speed is less than 20 km/hr • Design ESAL’s over 0.3 million

  45. Questions ?

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