Title: Overlay Design Workshop for Flexible Pavements
1Overlay Design Workshop for Flexible Pavements
- James A. Crovetti
- Marquette University
2WHRP Project Background
- Project 0092-07-12 Implementation of Flexible
Pavement Overlay Design Procedures - Project 0092-00-05 Development of Rational
Overlay Design Procedures for Flexible Pavements
(WHRP 05-12) - Project 0092-03-14 Development of
Modulus-to-Temperature Relations for HMA Mixtures
in Wisconsin (WHRP 05-11)
3Implementation of Flexible Pavement Overlay
Design Procedures
- Development of Overlay Design Software
- Revisions to FDM
- Knowledge Transfer
- Follow-Up
4FDM 14-10-30
- Structural Number Approach New
- Design Traffic, Soil Support
- Structural Deficiency Approach Overlay
- SNol SNnew SNeff
- Design Reliability
- Traffic, Materials
5Structural Deficiency Approach
- New pavement designed using WisPAVE (SNnew)
- Existing pavement analyzed to determine
structural adequacy (SNeff) - FWD data
- Component analysis
- Overlay thickness developed to overcome SN
shortage - hOL (SNnew-SNeff)/0.44
6Traffic Analysis
- Analyzed 2006 WIM data from 17 sites across the
State - ESALs per truck computed based on AASHTO
principles - Cumulative frequency of EALFs developed to select
appropriate factors for variable levels of
design reliability
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985.6 Design Reliability
EALF 0.3 (WisDOT FDM 14-1-5)
10Traffic-Based Design Reliability
1190 Design Reliability
67 Design Reliability
EALF 0.9
1.84
12Reliability-Based EALFs
13Recommended EALFs
14Overlay Design Software
- Eri and/or SNeff variations determined based on
FWD test results or component analysis - FWD provides SNeff and SSV without pavement
coring - New pavement (SNnew) and overlay (SNOL)
requirements determined based on current WisDOT
procedures with varying levels of design
reliability
15Component Analysis
16Component Analysis
17Component Analysis
18Overlay Design EquationsBased on FWD Data- No
Milling Before Overlay -
- Eri 22.04 - 3.645 D36 0.158 D362
- AUPP ½ (5D0 2D12 2D24 D36)
- E1/3T 10(3.574 - 0.437 Log AUPP - 0.066 Log
Eri) - SNeff 0.0055 (E1/3T) - 0.0012 Eri
- 0.144
19Subgrade EffectsEri 22.04 - 3.645 D36 0.158
D362
20Seasonal Subgrade Stiffness Variations
21Subgrade Estimations
22Correction Factors for Subgrade Strength
- FWD Testing during
- Critical Spring Period 2.48
- Late Spring 0.83
- Summer/Fall 0.50
23Constructed Pavement Layer Variations
F W D
Strong
Weak
24Strong Pavement
AUPP
25Weak Pavement
AUPP
26Pavement Strength, SNeff
- Eri 22.04 - 3.645 D36 0.158 D362
- AUPP ½ (5D0 2D12 2D24 D36)
- E1/3T 10(3.574 - 0.437 Log AUPP - 0.066 Log
Eri) - SNeff 0.0055 (E1/3T) - 0.0012 Eri
- 0.144
27Modulus-to-Temperature Effects for HMA
Log Mr 6.83 0.018 P200 0.044 Vv 0.00086
tp1.45 Pb.5
28Example Pavement
2 HMA E varies
3 HMA E450ksi
12 CABC Stress Hardening
240 Subgrade Stress Softening
Bedrock
29FWD Deflection Basins
30Temperature Corrected Deflections
31Overlay Design EquationsBased on FWD Data- With
Milling Before Overlay -
- AUPP2 8D0 6D8 2D12
- SNHMA 20.058 (AUPP2)-0.590649
- a1 SNHMA / THMA
- SNpost-mill SNeff a1Tmill
32Overlay Design Example
- 4-Lane State Trunk Highway
- 20 year overlay design
- CYADT12,000 DYADT17,000
- 7 Heavy Trucks
- Existing pavement contains 10 alligator cracking
and slight rutting - Thickness information from coring not available
(8 HMA from plans) - FWD test data provided from September testing
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47Lets Explore
- Importing FWD Data
- Adjusting Traffic
- Computing SN values and Overlay Thicknesses
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