1. FWD BackCalculation of Existing Pavement Structure

2. Pavement Structure

3. Critical Responses

4. Overlay Thickness Design (Critical Responses) Rutting—Vertical strain on top of the subgrade, within the unbound/bound base and AC layers Fatigue cracking—Horizontal strain at the bottom of AC layers Thermal cracking—Tensile stress at the surface of the AC layer

5. Structural Responses for AC/AC Overlays Critical structural responses are: –Tensile strain at the bottom of AC overlay –Tensile strain at the bottom of original AC layer –Vertical stress at the top of the subgrade

6. Structural Responses for AC/AC Overlays AC Overlay Existing AC Pavement  r Base Subgrade  v  r Bond Milling and Tack Coat

7. Structural Responses for AC/AC Overlays Other considerations: –Not all design procedures consider both strains at the bottom of the overlay and existing layer –Both strains should be examined as a minimum –If the existing layer is extensively cracked it may be modeled as a granular layer, thus consider only strains at the bottom of overlay

8. EverStress Input

9. EverStress Load & Evaluation Locations

10. EverStress Output

11. Pavement Deflection 012244872 60

12. EVERCALC General File

13. EVERCALC Deflection File Mil = 1/1000 inch

14. EVERCALC Output File

15. EVERCALC Summary File

16. EVERCALC General File

17. EVERCALC Output File