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Iowa DOT Perpetual Pavement Design Approach

Iowa DOT Perpetual Pavement Design Approach. APAI Perpetual Pavement Open House & Workshop October 2005. STRENGTH. Fall Winter Spring Summer. HMA. SUBBASE. SELECT. SUBGRADE. MICRO STRAIN. WORST. BEST. HMA THICKNESS. Perpetual Pavement Design Concept. MAT’L HIGH LOW

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Iowa DOT Perpetual Pavement Design Approach

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  1. Iowa DOTPerpetual PavementDesign Approach APAI Perpetual Pavement Open House & Workshop October 2005

  2. STRENGTH Fall Winter Spring Summer HMA SUBBASE SELECT SUBGRADE MICRO STRAIN WORST BEST HMA THICKNESS Perpetual Pavement Design Concept MAT’L HIGH LOW HMA-1 XXX XXX HMA-2 XXX XXX MOD XXX XXX SEL XXX XXX CLIMATE TENSILE STRAIN @ HMA = T inches MATERIAL

  3. 2-inch surface HMA 10M S ½ PG 64 –34 • 2-inch intermediate HMA 10M I ¾ PG 64 –34 • ??-inch base HMA 10M B 1 PG 58 -28 • 3-inch base HMA 10M B ½ (mod) PG 58 -28 hot mix asphalt 57 -29 46 -23 9” modified subbase (A-1 granular) 18” select subgrade (A-6 clay) Subgrade (A-6 clay)

  4. Computed Tensile Strain HMA thickness = 13

  5. Computed Tensile Strain HMA thickness = 14.5

  6. 2-inch surface HMA 10M S ½ PG 64 –34 2-inch intermediate HMA 10M I ¾ PG 64 –34 7.5-inch base HMA 10M B 1 PG 58 -28 3-inch base HMA 10M B ½ (mod) PG 58 -28 57 -29 46 -23 hot mix asphalt 9” modified subbase (A-1 granular) 18” select subgrade (A-6 clay) Subgrade (A-6 clay)

  7. Unique Design Features • Protection against HMA stripping for all lifts • 0.75% hydrated lime for all mixtures • Flexible initial base course • 3% design air voids[std- 4%] • ½-inch mixture[std- 1-inch] • 10-15 micron Film Thickness[std- 8-15] • 0.6-1.0 Filler:Bitumen Ratio[std- 0.6-1.4]

  8. A CASE STUDYThree Full-Depth HMAInterstate Pavements Michael Heitzman, Iowa Department of Transportation Dr. Brian Coree, Iowa State University International Symposium on Design and Construction of Long Lasting Asphalt Pavements June 2004

  9. Jasper/Poweshiek 1962 Cedar County 1962 Iowa/Johnson 1964

  10. Cedar Project Jasper/Poweshiek Project Iowa/Johnson Project

  11. Pavement Cross Section Cedar County 1.5 in. Surface 3.0 in. Binder 16.0 in. Base

  12. Pavement Cross Section Iowa / Johnson Counties 3.0 in. Binder 14.0 in. Base 6.0 in. Subbase 1.5 in. Surface FUTURE

  13. 7.2X 2.5X

  14. Rehabilitate vs Replace 1990 M 1 in 4.0 in 1968 2.0 in 1976 3.0 in 1984 M2 in 3.0 in 1991 M 1 in 4.0 in

  15. JASPER/POWESHIEK REHABILITATIONField Investigation - Coring Offset from crack (m) 0 0.6 1.2 1.8 2.4 3 0 100 200 HIGH Depth of intact core (mm) 300 400 MOD. 500 LOW 600 MP-179 Crk-5 high severity MP-179 Crk-1 moderate severity MP-176 Crk-12 moderate severity MP-176 Crk-34 low severity MP-179 Crk-15 low severity

  16. Rehabilitate 4-inch 1968 2.0 in 1984 M 2 in 3.0 in

  17. 14.5” hot mix asphalt 9” modified subbase (A-1 granular) 18” select subgrade (A-6 clay) Subgrade (A-6 clay) 1962 v 2005

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