Perpetual Pavement Design

1
Perpetual Pavement Design
Canadian User Producer Group for
Asphalt Saskatoon, Saskatchewan Nov. 16th 2008
John DAngelo Federal Highway Administration Washi
ngton, DC
2
Appian way in Italy
Experienced based design Build it thick Build it
with durable materials It will last
3
Pavement Design

• In a modern world can we afford to over design?
• Limited resources
• Limited money
• High demand
• How do we design for just the right performance?

4
Fatigue Theory
High Strain Short Life Low Strain Long Life
5
Fatigue Cracking
6
Fatigue Cracking
7
Traditional Fatigue Plot
8
Fatigue Theory for Thick Pavements
High Strain Short Life Low Strain Unlimited
Life
70
9
(No Transcript)
10
70 Micro Strain Test
11
FAILURE MODES
12
Eventual Distress
13
(No Transcript)
14
Goal of Perpetual Pavement Design

• Design the structure such that there are no deep
  structural distresses
• Bottom up fatigue cracking
• Structural rutting
• All distresses can be quickly remedied from
  surface
• Result in a structure with Perpetual or Long
  Life

15
Surface Distresses Only
Top Down Cracking
Non-Structural Rutting
16
Dynamic Modulus Test
17
Soil Modulus Testing
18
Dynamic Cone Penetration
Mass
Rod
Reference
19
FWD Testing
20
Traffic
21
Tire has a total load P, spread over a
circular area with a radius of a, resulting in a
contact pressure of p.
Pavement Reactions
Layer 1 HMA E1
Deflection (d)
No horizontal boundary, assume layers extend infi
nitely.
h1
Tensile Strain (et)
Layer 2 Granular Base E2
h2
Layer 3 Subgrade Soil E3
Compressive Strain (ev)
No bottom boundary, assume soil goes on
infinitely.
Figure 2. Layered Elastic Model Representation of
a Pavement.
22
Perpetual Pavement Design
French concept High modulus high binder content
base. California concept- High strain tolerance
polymer asphalt base. New approach- combine both
with stiff agg. base to reduce cost.
23
New Jersey I-287Surface Cracking
Solution Mill 4 and Overlay with 5
24
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.

25
References