Perpetual Pavements. A Success Story. Le cas du Don Valley Parkway à Toronto. JOURNÉE DU BITUME mars 2004 Hôtel Delta à Trois-Rivières

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1 Perpetual Pavements A Success Story. Le cas du Don Valley Parkway à Toronto. JOURNÉE DU BITUME mars 2004 Hôtel Delta à Trois-Rivières Vince Aurilio, P. Eng. Ontario Hot Mix Producers Association Asphalt Institute

2 The Challenge Stress Increased truck traffic Increased allowable maximum loads Increased tire pressures Slow moving or standing loads subject pavements to higher than normal stress conditions.

3 Perpetual Pavement Concept Bottom-up Design and Construction Foundation» Stable Paving Platform» Minimize Seasonal Variability and Volume Change in Service Fatigue Resistant Lower Asphalt Layer Rut Resistant Upper Asphalt Layers

4 Perpetual Pavement Concept Foundation Requirements Drainage As Needed Consider Maintenance Requirements Seasonal Changes Special Conditions Frost Heave/Thaw Weakening Expansive Soils

5 Mechanistic Performance Criteria Under 9 Kip Half-Axle Limit Bending to < 65-70µε (Monismith, Von Quintus, Nunn) Thick HMA (> 8 ) Base (as required) Limit Vertical Subgrade Strain to < 200µε Subgrade

6 Relationship of Tensile Strain vs. Fatigue Life» Thin Asphalt Pavement = Higher Strain» Higher Strain = Shorter Fatigue Life Compressive Strain Strain Indefinite Fatigue Life Tensile Strain Fatigue Life

7 Perpetual Pavement Design Strategy Lower Tensile Strain by Increasing Pavement Thickness and/or Increasing Stiffness of Intermediate Layer» Strain Below Fatigue Limit = Indefinite Life Compressive Strain Strain Indefinite Fatigue Life 65-70µε Tensile Strain Fatigue Life

8 Perpetual Pavement Concept Indefinite structural life eliminate bottom-up distresses and reconstruction Requires only periodic resurfacing and maintenance confine distresses to surface Minimize traffic closures

9 Performance Goals - Avoid These HMA Repeated Bending Leads to Fatigue Cracking Base Subgrade Repeated Deformation Leads to Rutting

10 }4 to 6 Zone Of High Compression SMA, OGFC or Superpave High Modulus Rut Resistant Material (Varies As Needed) Max Tensile Strain Flexible Fatigue Resistant Material 3-4 Pavement Foundation

11 Material Selection Rut Resistant Upper Layers Aggregate Interlock» Crushed Particles» Stone-on-Stone Contact Binder» High Temperature PG» Polymers» Fibers Air Voids» Avg. 4% to 6% In-Place Surface» Renewable» Tailored for Specific Use

12 STONE MATRIX ASPHALT Stone Skeleton Stones Filler Sand Bitumen Fibers + Mastic S TONE M ASTIC A SPHALT

13 F

14 Rehabilitation Possible Distresses Top-Down Fatigue Thermal Cracking Raveling Solutions Mill & Fill Thin Overlay Structure Remains Intact 2-4 High Quality SMA, OGFC or Superpave 20+ Years Later

15 FHWA - Data from Long-Term Pavement Performance Study Data from GPS-6 (FHWA-RD ) Conclusions Most AC Overlays > 15 years before Rehab Many AC Overlays > 20 years before Significant Distress Thicker overlays mean less: Fatigue Cracking Transverse Cracking Longitudinal Cracking

16 Perpetual Pavement Structure Lasts 50+ years.» Bottom-Up Design and Construction» Indefinite Fatigue Life Renewable Pavement Surface.» High Rutting Resistance» Tailored for Specific Application Consistent, Smooth and Safe Driving Surface. Environmentally Friendly Avoids Costly Reconstruction.

17 UK Research Thickness of asphalt layers (mm) TRL Design Chart DBM DBM50 HDM 100 TRL Design life (msa)

18 Overall Summary TRL n No structural deformation or roadbase fatigue cracking. n Distresses confined to surface n Rutting n Cracking n Roadbase stiffens with age and reduces deflection.

19 References TRB Circular No. 503 On-line at www4.nas.edu

20 Asphalt Institute Research Load Load Reaction Deflection Reaction

21 Test Parameters Test temperature: 20 C Failure Defined as 50% Initial Stiffness (after conditioning) Test Termination Criteria: 25% of Original Stiffness or 4,000,000 Cycles Note: 4,000,000 Cycles Simulates 40,000,000 ESAL s Rita Leahy, 1994 AAPT

22 Test Matrix Mix Air Voids Strain Levels (µε) 19-mm Superpave 7% for Optimum AC Content < 7% for Opt+ Test cells in triplicate Used PG Optimum AC Content Optimum+ (+0.5% AC) 800 X X 400 X X 200 X X 100 X X 70 X X Opt mixes compacted to 7% voids Same compactive effort for Opt and Opt +

23 Analyzed Data Using Three Different Methodologies Traditional Failure defined as 50% of original stiffness Dissipated Energy Ratio (DER) Carpenter and Ghuzlan Energy Ratio Analysis Rowe and Bouldin

24 Typical 800µε Stiffness Data Cycles vs. Stiffness 800µε Stiffness (Mpa) ,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000 18,000 Cycles

25 Typical 400µε Stiffness Data Cycles vs. Stiffness 400µε Stiffness (Mpa) ,000 40,000 60,000 80, , ,000 Cycles

26 Typical 200µε Stiffness Data Stiffness vs. Cycles 200µε Stiffness (Mpa) Cycles Note: Reducing strain by half extends fatigue life ~10X

27 Typical 100µε Stiffness Data Cycles vs. Stiffness 100µε Stiffness (Mpa) ,000,000 2,000,000 3,000,000 4,000,000 5,000,000 Cycles

28 Typical 70µε Stiffness Data Cycles vs. Stiffness 70µε Stiffness (Mpa) ,000,000 2,000,000 3,000,000 4,000,000 5,000,000 Cycles

29 Cycles to Failure vs. Strain Optimum AC Content Optimum Optimum Strain ,000 10, ,000 1,000,000 10,000, ,000,000 Cycles to Failure 100,000 1,000, ,000,000 1,000,000,000 10,000,000 Estimated ESALs To Failure

30 Cycles to Failure vs. Strain Optimum AC Content Optimum Optimum + Strain traditional failure model 0 1,000 10, ,000 1,000,000 10,000, ,000,000 Cycles to Failure 100,000 1,000, ,000,000 1,000,000,000 10,000,000 Estimated ESALs To Failure

31 PERPETUAL PAVEMENT AWARD PAST FUTURE

32 Don Valley Parkway

33 Don Valley Parkway APA Perpetual Pavement Award First winner in Canada First municipal road First to use SMA

34 Construction History First section built in 1950 Extended by 23 km in 1957 Completed to Hwy 401 in 1965 Extension in 1957 designed to accommodate high traffic volume in future Carries about 80,000 to 100,000 vehicles per day or about 1.2 million ESAL s 50 mm HL 1 over 170 mm HL 8 over 80 HL 6

35 Performance History First resurfacing started in the 70 s; second in 1990 First major rehab in 1978; HL 1 modified with asbestos fibres good performance for over 20 years OFC used for years to reduce tire noise and spray; discontinued in 1985 due to short life In the 90 s move to DFC and SMA

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38 OGRA Recognizes DVP Perpetual Pavement Award

39 What s next? NCHRP 9-38 Endurance Limit of HMA to Prevent Fatigue Cracking in Flexible Pavements $750K, 2-year research project Recently awarded to NCAT Dr. E. Ray Brown, Principal Investigator

40 Questions, comments?