Thickness Design 1972 AASHTO Method
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Thickness Design
1972 AASHTO Method
CIVL 3137 51
AASHO Road Test
CIVL 3137 52
AASHO Road Test
Source: WSDOT Pavement Guide Interactive CD-ROM
CIVL 3137 53
AASHO Road Test
Source: http://www.fhwa.dot.gov
CIVL 3137 54
AASHO Road Test
Source: WSDOT Pavement Guide Interactive CD-ROM
CIVL 3137 55
AASHO Road Test
Source: WSDOT Pavement Guide Interactive CD-ROM
CIVL 3137 56
AASHO Road Test
Source: WSDOT Pavement Guide Interactive CD-ROM
CIVL 3137 57
AASHO Road Test
Source: WSDOT Pavement Guide Interactive CD-ROM
CIVL 3137 58
AASHO Road Test
Source: WSDOT Pavement Guide Interactive CD-ROM
CIVL 3137 59
AASHTO Design Equation
LifetimeESALs
SubgradeSupport
Ride QualityThreshold
Structural Number(Flexural Rigidity)
t
10
10 18 10 i
5.19
4.2 plog14.2 1.5log W 9.36log SN 1 0.20 log 0.372 S 3.01094 R0.4
SN 1
RegionalFactor
1972
CIVL 3137 60
Ride Quality Threshold (pt)
Very good
Good
Fair
Poor
Very poor
5
4
3
2
1
0
PSI
ESALS
Limit for Low-Volume Roads
Limit for High-Volume Roads
Failure
4.2
1.5
CIVL 3137 61
Regional Factor (R)
Condition R value
Roadbed materials frozen to a depth of 5 in. or more (winter)
Roadbed materials dry (summer and fall)
Roadbed materials wet (spring thaw)
0.2 – 1.0
0.5 – 1.5
4.0 – 5.0
CIVL 3137 62
Regional Factor (R)
CIVL 3137 63
Soil Support Value (S)
AASHTO Design Nomograph
CIVL 3137 64
CAREFUL!
20-year Lifept = 2.5 only
CIVL 3137 69
AASHTO Pavement Design
Subbase
Base
Asphalt
D2
D3
D1
AASHTO Layer Coefficients
CIVL 3137 70
CIVL 3137 71
Pavement Design
Sandy GravelSubbase
Crushed StoneBase
Dense-GradedAsphalt
10"
12"
5"
SN = ??
CIVL 3137 72
Pavement Design
SandSubbase
Crushed StoneBase
Dense-GradedAsphalt
6"
8"
?
SN = 2.7
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