Superpave TM Asphalt Grading

Transcription

1 Superpave TM Asphalt Grading

2 Asphalt Cement Performance Elastic Solid Viscoelastic Solid Viscous Liquid True Liquid 0ºF 77ºF 140ºF 275ºF Minimum Service Temp Average Service Temp Maximum Service Temp Mixing Placing Temp Penetration Number Absolute Viscosity Kinematic Viscosity CIVL

3 Traditional Grading Temperature ( C) Viscosity (cp)

4 Performance Grading Temperature ( C) Dynamic Shear Modulus (kpa)

5 Superpave Grading Uses fundamental physical and mechanical properties, not index properties Performance-based: criteria remain constant but the test temperature changes Lowest 1-day single temperature Highest 7-day average temperature Explicitly addresses aging, thermal cracking, fatigue cracking and rutting CIVL

6 Superpave Grading Equipment Rotational Viscometer Dynamic Shear Rheometer Rolling Thin-Film Oven Pressure Aging Vessel Bending Beam Rheometer Direct Tension Tester Purpose Properties at construction temps Properties at high service temps Aging due to volatilization Aging due to oxidation Properties at low service temps Properties at low service temps CIVL

7 Performance Grading CIVL

8 Performance Grading CIVL

9 Rotational Viscometer 20 rpm Can be used with modified or unmodified binders w/out clogging The viscosity of the unaged binder must be less than 3000 cp at 135ºC for good pumping and mixing CIVL

10 Viscosity of Common Liquids Water Cream Vegetable Oil Tomato Juice Honey Chocolate Syrup Sour Cream Ketchup Peanut Butter Vegetable Shortening 1 centipoise 20 centipoise 100 centipoise 200 centipoise 2000 centipoise centipoise centipoise centipoise centipoise centipoise CIVL

11 Rotational Viscometer CIVL

12 Dynamic Shear Rheometer Applied Stress Applied Stress 1.59 Hz time Fixed plate 46 o C to 82 o C CIVL

13 Dynamic Shear Rheometer CIVL

14 Dynamic Shear Rheometer Stress time Stress time Strain time Strain time Elastic Solid = 0 deg Viscous Liquid = 90 deg CIVL

15 Dynamic Shear Rheometer max Stress t G * max min time min max min Strain max time f t min CIVL

16 Dynamic Shear Rheometer Applied Stress G*/sin of unaged binder must exceed 1.00 kpa at the high service temperature to prevent rutting Fixed plate CIVL

17 Rolling Thin-Film Oven 85 min Air Jet 325 o F Sample Bottle Simulates aging of asphalt cement during mixing and laydown CIVL

18 Rolling Thin Film Oven CIVL

19 Dynamic Shear Rheometer Applied Stress G*/sin of the stiffer RTFO-aged binder must exceed 2.2 kpa at the high service temperature to prevent rutting Fixed plate CIVL

20 Pressure Aging Vessel 20 hours 300 psi sample pan air o C Simulates aging of asphalt cement over years due to oxidation CIVL

21 Dynamic Shear Rheometer Applied Stress G* sin of the stiffer PAV-aged binder must be less than 5000 kpa at the mean of the high and low service temperatures to prevent fatigue cracking Fixed plate CIVL

22 Bending Beam Rheometer 100 g Air Bearing P Fluid Bath D 0ºC to -36 o C t CIVL

23 Bending Beam Rheometer S t P t L 3 3 4bh D t P Creep Stiffness D t CIVL

24 Bending Beam Rheometer CIVL

25 Bending Beam Rheometer CIVL

26 Bending Beam Rheometer 100 g Fluid Bath Air Bearing S(t) of the PAV-aged binder must not exceed 300 MPa after 2 hours at the low service temperature to prevent thermal cracking 0ºC to -36 o C CIVL

27 Direct Tension Tester L eff L eff + L f L L eff 0ºC to -36 o C CIVL

28 Direct Tension Test CIVL

29 Direct Tension Tester f of the PAV-aged binder must exceed 1% at the low service temperature to prevent thermal cracking CIVL

30 Superpave Grading High Grades PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82 Low Grades 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 Typical Performance Grade PG CIVL

31 Superpave Grading PG Performance Grade Maximum 7-day avg. pavement temperature Minimum 1-day pavement temperture CIVL

32 Superpave Grade Selection Based on Historical Weather Records at the Project Location Lowest 1-day Air Temperature Highest 7-day avg. Air Temperature CIVL

33 Superpave Grade Selection Based on Empirical Relationships Between Air and Pavement Temperature Lowest 1-day Pavement Temperature Highest 7-day avg. Pavement Temperature CIVL

34 Superpave Grade Selection PG70-22 PG Lowest 1-day Pavement Temperature Highest 7-day avg. Pavement Temperature CIVL

35 Normal Probability Distribution Standard Deviations CIVL

36 Superpave Grade Selection PG70-22 PG Lowest 1-day Pavement Temperature Highest 7-day avg. Pavement Temperature CIVL

37 Normal Probability Distribution PG % 16% Temperature ( C) CIVL

38 Superpave Grade Selection Reliability = (0.84)(0.70) = 59% PG64-16 ~30% ~70% ~84% ~16% Lowest 1-day Pavement Temperature Highest 7-day avg. Pavement Temperature CIVL

39 Superpave Grade Selection PG70-22 Reliability = (1.00)(0.98) = 98% ~2% ~98% ~100% ~0% Lowest 1-day Pavement Temperature Highest 7-day avg. Pavement Temperature CIVL

40 Superpave Binder Grades High Temperature, C CIVL

41 Superpave Binder Cost High Temperature, C 82 $ $ $ $ Cost per ton based on TDOT reimbursement rates for October 2012 CIVL

42 Grade Bumping PG PG PG PG CIVL

43 CIVL