11 - AASHTO Material Properties (NEW) - AASHTO... · AASHTO Design Equation 1986 2 10 10 18 10 10 R...
Transcript of 11 - AASHTO Material Properties (NEW) - AASHTO... · AASHTO Design Equation 1986 2 10 10 18 10 10 R...
Material Properties
AASHTO Design Equation
1986
2
10
10 18 10 10 R
5.19
4.2 plog4.2 1.5log W 9.36log SN 1 0.20 2.32log M 8.0710940.4SN 1
ConstructedPavement Subgrade
Structural Number
1 1 2 2 3 3SN a D a D a D
1 2 3, , Ra a a Mf
3
asphalt base subbase
4
Typical Layer Coefficients
Subbase
Base
Asphalt
D2
D3
D1Dense-graded asphaltSand asphaltCrushed stone baseSandy gravel baseCement-treated baseAsphalt-treated baseLime-treated baseSandy gravel subbaseSand subbase
0.440.400.140.070.200.300.200.110.08
Typical Layer Coefficients
Pavement Stresses @ 24"
0
1
2
3
4
5
6
7
8
-6 -4 -2 0 2 4 6
Offset (ft)
Stre
ss (p
si)
Subgrade onlySubgrade + 24" SubbaseSubgrade + 6" Subbase + 18" BaseSubgrade + 6" Subbase + 12" Base + 6" Asphalt
5
Resilient Modulus
6
Resilient Modulus
Axial strain
Dev
iato
r stre
ss
MR
7
Diametral Resilient Modulus
8
Asphalt Layer Coefficient
9
Granular Soils
Source: WSDOT Pavement Guide Interactive CD-ROM 10
Base Layer
2 100.249log 0.977 BSa E
21 k
BSE k
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AASHO Road Test
MoistureState
k1(psi)
k2(-)
Dry 8000 0.6Damp 4000 0.6Wet 3200 0.6
WARNING: We don’t actually use different values for different moisture states.This just illustrates the effects of moisture on base layer resilient modulus.
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Estimating Base
Asphalt Thickness
(in)
Subgrade Resilient Modulus (psi)
3000 7500 15,000
< 2 20 25 302 – 4 10 15 204 – 6 5 10 15> 6 5 5 5
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Base Layer Coefficient
14
CTB Layer Coefficients
15
ATB Layer Coefficients
16
Subbase Layer
3 100.227log 0.839 SBa E
21 k
SBE k
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AASHO Road Test
MoistureState
k1(psi)
k2(-)
Damp 5400 0.6Wet 4600 0.6
WARNING: We don’t actually use different values for different moisture states.This just illustrates the effects of moisture on base layer resilient modulus.
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Estimating Subbase
Asphalt Thickness
(in)
StressState(psi)
< 2 102 – 4 7.5> 4 5
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Subbase Layer Coefficients
20
Drainage Coefficients
1966
21
1972
t
10
10 18 10
5
i
.19
4.2 plog4.2 1.5log W 9.36log SN 1 0.20 10940.
1log 0.372 S 3.
S 1
0R4
N
t10
10 18 10
5.19
4.2 plog4.2 1.5log W 9.36log SN 1 0.20 10940.4SN 1
1986
10
t10
10 18 10
5.19
R
4.2 plog4.2 1.5log W 9.36log SN 1 0.20 10940.4S
2.32log M 8.07
N 1
Drainage Coefficients
1 1 2 2 2 3 3 3SN a D a D m a D m
2 3, m m drainagef
22
asphalt base subbase
Drainage Quality
Quality Water Removed Within
Excellent 2 hoursGood 1 dayFair 1 weekPoor 1 month
Very Poor No drainage
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Drainage Coefficients
Quality < 1% 1-5% 5-25% > 25%Excellent 1.40-1.35 1.35-1.30 1.30-1.20 1.20
Good 1.35-1.25 1.25-1.15 1.15-1.00 1.00Fair 1.25-1.15 1.15-1.05 1.00-0.80 0.80Poor 1.15-1.05 1.05-0.80 0.80-0.60 0.60
Very Poor 1.05-0.95 0.95-0.75 0.75-0.40 0.40
Percentage of Time Material Approaches Saturation
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AASHTO Design Equation
1986
25
10
10 18 10 10 R
5.19
4.2 plog4.2 1.5log W 9.36log SN 1 0.20 2.32log M 8.0710940.4SN 1
ConstructedPavement Subgrade
Seasonal Moisture Effects
Time
Mod
ulus
Winter Freeze
Spring Thaw
Recovery
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Seasonal Moisture Effects
27
WSDOT
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Minnesota DOT
Season IWinter
Season IIEarly Spring
Season IIILate Spring
Season IVSummer
Season VFall
Description All LayersAre Frozen
Base Thaws,SG Frozen
Base Recovers,SG Thaws
HMA Low,SG Recovers
All LayersAre Standard
Pavement Layer Moduli Relative to Fall ValuesHMA High High Standard Low StandardBase High Low Low Standard StandardSG High High Low Low Standard
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Minnesota DOT
Season IWinter
Season IIEarly Spring
Season IIILate Spring
Season IVSummer
Season VFall
Description All LayersAre Frozen
Base Thaws,SG Frozen
Base Recovers,SG Thaws
HMA Low,SG Recovers
All LayersAre Standard
Seasonal Modulus FactorsHMA 2.6 2.1 1.4 0.4 1.0BaseSG 22 2.4 0.73 0.75 1.0
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AASHTO Design Equation
1986
31
10
10 18 10 10 R
5.19
4.2 plog4.2 1.5log W 9.36log SN 1 0.20 2.32log M 8.0710940.4SN 1
ConstructedPavement Subgrade
AASHTO Design Equation
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10
10 18 10 10 R
5.19
4.2 plog4.2 1.5log W 9.36log SN 1 0.20 2.32log M 8.0710940.4SN 1
Q Ti
“i”representsablockoftimewithconstantMRItcouldbeamonth,aweek,aseason,etc.
10 18 18log 10 10 iTQii iW Q T W
“Standard” Vehicle
1 consumption per passageSS
dN
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Seasonal Damage per ESAL
i
ii TQ Q
18 i
1 1 udW 10 10 10
i
8
i 2.32TR i
1 1.18 10u10 M
Let
di = damage per ESAL in Season i
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Average Damage per ESAL
n n nf
i i i i i iQ Q Qi 1 i 1 i 1
1 1 1 1 1 ud f d f u f un n 10 10 n 10
fi = fraction of annual ESALs applied during Season i
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Effective Modulus
8
f 2.32R eff
1.18 10uM
R 0.431eff
3005Mu
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Example
Period MR ui N ui NDec-Feb 20,000 3
Mar 2500 1Apr-May 4000 2Jun-Nov 7000 6
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