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Perpetual Pavements Concept and History Iowa Open House October 5, 2005.

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Presentation on theme: "Perpetual Pavements Concept and History Iowa Open House October 5, 2005."— Presentation transcript:

1 Perpetual Pavements Concept and History Iowa Open House October 5, 2005

2 Perpetual Pavements Max Tensile Strain Pavement Foundation High Modulus Rut Resistant Material (Varies As Needed) Flexible Fatigue Resistant Material 75 - 100 mm 40-75 mm SMA, OGFC or Superpave } 100 mm to 150 mm Zone Of High Compression

3 Perpetual Pavements Value Quality... is what the customer gets out [of a product] and is willing to pay for. A product is not quality because it is hard to make and costs a lot of money... This is incompetence. Customers pay only for what is of use to them and gives them value. Nothing else constitutes quality. Peter Drucker

4 Perpetual Pavements Economics Time Total Costs Alternative Perpetual Pavement

5 Perpetual Pavements Why are Perpetual Pavements Important? Lower Life Cycle Cost –Better Use of Resources –Low Incremental Costs for Surface Renewal Lower User Delay Cost –Shorter Work Zone Periods –Off-Peak Period Construction

6 Perpetual Pavements Design

7 Perpetual Pavements Mechanistic Performance Criteria Under ESAL Limit Bending to < 65  (Monismith, Von Quintus, Nunn, Thompson) Limit Vertical Compression to < 200  (Monismith, Nunn) Thick HMA (> 200 mm) Base (as required) Subgrade

8 Perpetual Pavements ›Fatigue Resistant Asphalt Base »Minimize Tensile Strain with Pavement Thickness »Thicker Asphalt Pavement = Lower Strain »Strain Below Fatigue Limit = Indefinite Life Compressive Strain Tensile Strain Strain Fatigue Life Indefinite Fatigue Life

9 Perpetual Pavements PerRoad


11 Perpetual Pavements DBM DBM50 HDM Design life (msa) Thickness of asphalt layers (mm) 500 400 300 200 100 0 TRL TRL Design Chart 10010

12 Perpetual Pavements Perpetual Pavement versus Conventional Design AASHTO PerRoad

13 Perpetual Pavements Construction

14 Perpetual Pavements Foundation - Illinois 0 5 10 15 20 25 0123456789 CBR Required Thickness Above Subgrade, inches Remedial procedure required Remedial procedure optional No remedial procedure required

15 Perpetual Pavements Rod Reference Mass

16 Perpetual Pavements Compaction Support Weak!!! Weak Support Leads to Poor Compaction!

17 Perpetual Pavements Compaction Support Strong!!! Strong Support Helps Compaction!

18 Perpetual Pavements 30 O F Surface, 40 O F Air Temperature, 15 mph wind

19 Perpetual Pavements Performance

20 Perpetual Pavements Performance of Washington Interstate Flexible Pavements (based on 284 km) 12.4230 (9.2)31.6Average 2 to 25100 to 34523 to 39Range Time from Original Construction to First Resurfacing (years) Thickness of Original AC (mm (in.)) Time Since Original Construction (years) Statistic

21 Perpetual Pavements Ohio Study of Flexible Pavements Examined Performance on 4 Interstate Routes –HMA Pavements - Up to 34 Years without Rehabilitation or Reconstruction –“No significant quantity of work... for structural repair or to maintain drainage of the flexible pavements.” –Only small incremental increases in Present Cost for HMA pavements.

22 Perpetual Pavements FHWA - Data from Long-Term Pavement Performance Study Data from GPS-6 (FHWA-RD-00-165) 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

23 Perpetual Pavements { Rehabilitation 50 - 100 mm Structure Remains Intact Possible Distresses › Top-Down Fatigue › Thermal Cracking › Raveling Solutions › Mill & Fill › Thin Overlay High Quality SMA, OGFC or Superpave 20+ Years Later

24 Perpetual Pavements Life Cycle Costs Important to consider –Initial Costs –Rehabilitation and Maintenance Costs –Reconstruction costs Should break costs into –Agency costs –User Costs Time

25 Perpetual Pavements Design Comparison – Low Volume 50 year design 1 mile, 2 Lane, 12 ft lanes Traffic: 5000 ADT (Rural Setting) Muench, et al., 2004 Subgrade 12” Granular Base 6” HMA 6” Granular Base 3” HMA Conventional ($230,000) Perpetual ($360,000)

26 Perpetual Pavements Rehabilitation Schedule Conventional Design (3” HMA/6” GB) –1.75” Overlay in years 6, 15, 31 and 40 –Rebuild at 25 years Perpetual Design (6” HMA/12” GB) –1.75” overlay every 13 years Values based on WSDOT Experience Muench, et al., 2004

27 Perpetual Pavements Cost Analysis Used LCCA Software Considered variability of inputs User delay not significant Muench, et al., 2004

28 Perpetual Pavements What About User Delay Costs?

29 Perpetual Pavements WZ User Cost Comparison 4-lane 40,000 AADT LCCA Software –Delay calculations based on Highway Capacity Manual Compare work-zone alternatives –24 hour closure –20 hour closure –11 hour closure

30 Perpetual Pavements Option 1 – 24 Hr Closure Cost/mile/day $116,000 85% of cost is waiting to move through WZ

31 Perpetual Pavements Option 2 – 20 Hr Closure Cost/mile/day $42,000

32 Perpetual Pavements Option 3 – 11 Hr Closure Cost/mile/day $12,000 No stopping!

33 Perpetual Pavements 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.

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