Transcript Perpetual Pavements - APAI

Perpetual Pavements
Perpetual Pavements
Concept and History
Iowa Open House
October 5, 2005
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Perpetual Pavements
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40-75 mm SMA, OGFC or Superpave
100 mm
to
150 mm
Max Tensile Strain
Zone
Of High
Compression
High Modulus
Rut Resistant Material
(Varies As Needed)
Flexible Fatigue Resistant
Material 75 - 100 mm
Pavement Foundation
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
Perpetual Pavements
Economics
Alternative
Total
Costs
Perpetual
Pavement
Time
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
Perpetual Pavements
Design
Perpetual Pavements
Mechanistic Performance Criteria
Under ESAL
Limit Bending to < 65me
(Monismith, Von Quintus, Nunn,
Thompson)
Thick HMA
(> 200 mm)
Base (as required)
Subgrade
Limit Vertical Compression to < 200me (Monismith, Nunn)
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
Strain
Indefinite
Fatigue
Life
Fatigue Life
Tensile Strain
Perpetual Pavements
PerRoad
Perpetual Pavements
RATE OF RUTTING vs ASPHALT THICKNESS
1000
100
Rate of
rutting
(mm/msa) 10
1
0.1
TRL
0
100
200
300
Thickness of bituminous layer (mm)
400
Perpetual Pavements
500
TRL Design Chart
DBM
400
DBM50
HDM
Thickness 300
of asphalt
layers
200
(mm)
100
0
TRL
10
100
Design life (msa)
Perpetual Pavements
Perpetual Pavement versus Conventional Design
HMA Thickness, in.
25
20
AASHTO
15
PerRoad
10
5
0
0.1
1
10
Traffic, ESAL
100
1000
Perpetual Pavements
Construction
Perpetual Pavements
25
No remedial procedure required
Required Thickness Above
Subgrade, inches
Foundation - Illinois
20
15
10
Remedial procedure
required
5
Remedial
procedure
optional
0
0
1
2
3
4
5
CBR
6
7
8
9
Perpetual Pavements
Mass
Rod
Reference
Perpetual Pavements
Compaction Support
Weak Support
Leads to Poor Compaction!
Weak!!!
Perpetual Pavements
Compaction Support
Strong Support
Helps Compaction!
Strong!!!
Perpetual Pavements
Temperature, F
300
30OF Surface, 40OF Air Temperature, 15 mph wind
275
250
225
200
175
150
0
5 10 15 20 25 30 35 40 45 50 55 60
Time, minutes
1.5"
2"
3"
Perpetual Pavements
Performance
Perpetual Pavements
Performance of Washington Interstate Flexible Pavements
(based on 284 km)
Statistic
Time Since
Original
Construction
(years)
Thickness of
Original AC
(mm (in.))
Average
31.6
230 (9.2)
Time from
Original
Construction
to First
Resurfacing
(years)
12.4
Range
23 to 39
100 to 345
2 to 25
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.
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
Rehabilitation
Perpetual Pavements
Possible Distresses
Structure Remains Intact
› Top-Down Fatigue
{
50 - 100 mm
Solutions
› Thermal Cracking
› Mill & Fill
› Raveling
› Thin Overlay
High Quality SMA, OGFC or Superpave
20+ Years
Later
Perpetual Pavements
Life Cycle Costs
• Important to consider
– Initial Costs
– Rehabilitation and Maintenance Costs
– Reconstruction costs
Time
• Should break costs into
– Agency costs
– User Costs
Perpetual Pavements
Design Comparison – Low Volume
• 50 year design
• 1 mile, 2 Lane, 12 ft lanes
• Traffic: 5000 ADT (Rural Setting)
6” HMA
Perpetual
($360,000)
Conventional
($230,000)
3” HMA
12” Granular Base
6” Granular Base
Subgrade
Muench, et al., 2004
Perpetual Pavements
Rehabilitation Schedule
• Conventional Design (3” HMA/6” GB)
– 1.75” Overlay in years 6, 15, 31 and 40
– Rebuild at 25 years
• Perpetual Design (6” HMA/12” GB)
– 1.75” overlay every 13 years
• Values based on WSDOT Experience
Muench, et al., 2004
Perpetual Pavements
Cost Analysis
• Used LCCA Software
• Considered variability of inputs
• User delay not significant
700,000
,$
PV
N
600,000
500,000
400,000
300,000
200,000
100,000
0
Perpetual
Conventional
Pavement Type
Muench, et al., 2004
Perpetual Pavements
What About User Delay Costs?
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
Perpetual Pavements
Option 1 –
24 Hr Closure
Cost/mile/day
$116,000
85% of cost is waiting
to move through WZ
Perpetual Pavements
Option 2 –
20 Hr Closure
Cost/mile/day
$42,000
Perpetual Pavements
Option 3 –
11 Hr Closure
Cost/mile/day
$12,000
No stopping!
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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