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Perpetual Pavements Concept and History. Iowa Open House October 5, 2005. www. AsphaltAlliance .com. }. 40-75 mm SMA, OGFC or Superpave. 100 mm to 150 mm. Zone Of High Compression. High Modulus Rut Resistant Material (Varies As Needed).
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Perpetual Pavements Concept and History Iowa Open House October 5, 2005 www.AsphaltAlliance.com
} 40-75 mm SMA, OGFC or Superpave 100 mm to 150 mm Zone Of High Compression High Modulus Rut Resistant Material (Varies As Needed) Flexible Fatigue Resistant Material 75 - 100 mm Max Tensile Strain Pavement Foundation
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
Economics Total Costs Alternative Perpetual Pavement Time
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 Why are Perpetual Pavements Important?
Under ESAL Limit Bending to < 65me (Monismith, Von Quintus, Nunn, Thompson) Limit Vertical Compression to < 200me (Monismith, Nunn) Mechanistic Performance Criteria Thick HMA (> 200 mm) Base (as required) Subgrade
Fatigue Resistant Asphalt Base • Minimize Tensile Strain with Pavement Thickness • Thicker Asphalt Pavement = Lower Strain • Strain Below Fatigue Limit = Indefinite Life Compressive Strain Indefinite Fatigue Life Strain Fatigue Life Tensile Strain
1000 100 Rate of rutting (mm/msa) 10 1 0.1 0 100 200 300 400 Thickness of bituminous layer (mm) RATE OF RUTTING vs ASPHALT THICKNESS TRL
500 TRL Design Chart DBM DBM50 HDM 400 300 Thickness of asphalt layers (mm) 200 100 0 10 100 TRL Design life (msa)
Perpetual Pavement versus Conventional Design AASHTO PerRoad
25 20 15 Subgrade, inches Required Thickness Above 10 5 0 0 1 2 3 4 5 6 7 8 9 CBR Foundation - Illinois No remedial procedure required Remedial procedure required Remedial procedure optional
Mass Rod Reference
Compaction Support Weak Support Leads to Poor Compaction! Weak!!!
Compaction Support Strong Support Helps Compaction! Strong!!!
Statistic Time Since Original Construction (years) Thickness of Original AC (mm (in.)) Time from Original Construction to First Resurfacing (years) Average 31.6 230 (9.2) 12.4 Range 23 to 39 100 to 345 2 to 25 Performance of Washington Interstate Flexible Pavements (based on 284 km)
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. Ohio Study of Flexible Pavements
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 FHWA - Data from Long-Term Pavement Performance Study
Rehabilitation • Possible Distresses • Top-Down Fatigue • Thermal Cracking • Raveling • Solutions • Mill & Fill • Thin Overlay High Quality SMA, OGFC or Superpave { 50 - 100 mm 20+ Years Later Structure Remains Intact
Important to consider Initial Costs Rehabilitation and Maintenance Costs Reconstruction costs Should break costs into Agency costs User Costs Life Cycle Costs Time
50 year design 1 mile, 2 Lane, 12 ft lanes Traffic: 5000 ADT (Rural Setting) Design Comparison – Low Volume 6” HMA Perpetual ($360,000) Conventional ($230,000) 12” Granular Base 3” HMA 6” Granular Base Subgrade Muench, et al., 2004
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 Rehabilitation Schedule Muench, et al., 2004
Used LCCA Software Considered variability of inputs User delay not significant Cost Analysis Muench, et al., 2004
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 WZ User Cost Comparison
85% of cost is waiting to move through WZ Option 1 – 24 Hr Closure Cost/mile/day$116,000
Option 2 – 20 Hr Closure Cost/mile/day$42,000
No stopping! Option 3 – 11 Hr Closure Cost/mile/day$12,000
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. Perpetual Pavement www.AsphaltAlliance.com