1 Mix Design for HMA Mix Design for HMA Recycling Recycling National Symposium on HMA Energy & Recycling October 9, 2007 Recycling Group
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Mix Design for HMA Mix Design for HMA RecyclingRecycling
National Symposium on HMA Energy & RecyclingOctober 9, 2007Recycling Group
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Do You Need A Mix Design?
Yes!!!!
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Do You Need To Account for Properties of RAP?
Asphalt BinderAggregateAsphalt Binder Content
Yes!!!!
4
Are Mix Designers Concerned About the Following?
Yes Yes
5
Are Mix Designers Concerned About the Following?
Yes Yes
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Guidance
NAPA – Quality Improvement Series 124Purdue - NCHRP Web Document 30Purdue - NCHRP Report 452New NCHRP Study
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Materials Evaluation
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Virgin Asphalt Considerations
0 to 15% no change in binder grade16 to 25% one temperature grade lower (high and low end)>25% use blending charts
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Blending Charts
46
52
58
64
70
76
82
0 10 20 30 40 50 60 70 80 90 100
Percentage of RAP
Failu
re T
empe
ratu
re fo
r Hig
h Te
mpe
ratu
re S
tiffn
ess
of A
spha
lt B
inde
r, °C
46
52
58
64
70
76
82
Failu
re T
empe
ratu
re fo
r Hig
h Te
mpe
ratu
re S
tiffn
ess
of A
spha
lt B
inde
r, °C
Failure temperature of 79.7°C for RAP
Failure temperature of 58.8°C or greater for virgin asphalt binder
Desire a high temperature grade of 64°C
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Importance of Blending Charts
1
10
100
70 76 82 88
Temperature, °C
Hig
h Te
mpe
ratu
re S
tiffn
ess
of E
xtra
cted
and
R
ecov
ered
Asp
halt
Bin
der,
G*/s
inδ,
kPa
Location 1 Location 2 Location 3 Location 4 Location 5
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What Happens During Mixing with RAP?
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Looking at the Asphalt Films
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Air voidsVirgin BinderRAP Binder
Aggregate
Time 0
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Air voids
Blended Binder
Extent of virgin binder diffusion
RAP Binder, no virgin binder diffusionTime 0 + X
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Air voids
RAP Binder,no virgin binder diffusion
Completely blended binder
Extent of virgin binderdiffusion
Time 0 + Y
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Importance of Material Variability
0
1
2
3
4
5
6
7
8
1 2 3 4 5 6 7 8
Sample Number
Hig
h Te
mpe
ratu
re S
tiffn
ess
of E
xtra
cted
and
Rec
over
ed A
spha
lt B
inde
r, 88
°C G
*/sin
d, k
Pa
17
Aggregate Considerations
ShapeSurface textureSpecific gravityFrictionOther properties
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QC from RAP (Asphalt Free Gradations)
Test #Reflux Asphalt
Content, %DWA 3/4-in 1/2-in 3/8-in No. 4 No. 16 No. 50 No. 2001 3.25 100 98 89 66 48 27 12.32 3.52 100 99 91 70 42 23 10.93 3.93 100 100 96 74 46 26 11.84 3.83 100 98 92 74 45 22 8.65 3.79 100 98 92 73 45 25 11.76 3.05 100 98 91 66 39 22 11.47 3.31 100 97 90 68 41 23 11.38 3.47 100 98 91 72 44 24 10.4
Average 3.52 100 98 92 70 44 24 11.1 Standard Deviation 0.31 0.0 0.9 2.1 3.4 2.9 1.9 1.1
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Mix Design Procedure
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Mix Considerations
VolumetricsGradationAsphalt binderEngineering properties
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Mix Considerations
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Plant Verification
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Plant VerificationDate
Sampled Sample LocationTest
Purpose
% Passing 3/4 in.
% Passing 1/2 in.
% Passing 3/8 in.
% Passing
No. 4
% Passing No. 16
% Passing No. 50
% Passing No. 200
Asphalt Content %, DWA
100 95 80 54 3.00100 100 90 64 7.00100 98 87 60 32 16 6.21
4/9/2007 Hot Sample Process 100.0 98.7 90.8 65.1 33.6 17.4 6.8 4.824/9/2007 Hot Sample Process 100.0 98.8 87.5 59.5 30.0 15.3 6.1 4.80
4/10/2007 Hot Sample Process 100.0 97.5 86.7 61.6 31.4 15.5 5.8 5.044/10/2007 Hot Sample Process 100.0 97.9 89.7 65.5 31.5 15.2 5.6 5.074/11/2007 Hot Sample Process 100.0 97.9 89.7 65.5 31.5 15.2 5.6 5.074/11/2007 Hot Sample Process 100.0 98.4 89.3 63.8 32.9 15.8 6.5 5.094/12/2007 Hot Sample Process 100.0 97.4 82.9 55.3 28.6 15.0 5.5 5.144/13/2007 Hot Sample Process 100.0 100.0 92.0 66.7 33.3 16.5 6.1 4.804/16/2007 Hot Sample Process 100.0 100.0 93.0 69.0 34.8 16.3 6.4 5.314/16/2007 Hot Sample Process 100.0 100.0 96.1 67.5 34.0 17.0 6.44/16/2007 Hot Sample Process 100.0 100.0 88.6 62.0 34.9 18.3 7.14/16/2007 Hot Sample Process 100.0 98.6 90.5 64.9 38.6 21.5 9.44/16/2007 Hot Sample Process 100.0 97.1 85.3 57.4 30.0 15.4 5.4 5.014/17/2007 Hot Sample Process 100.0 100.0 91.4 60.0 31.1 16.1 5.2 4.964/17/2007 Hot Sample Process 100.0 97.2 86.1 59.7 31.8 17.1 6.8 5.194/17/2007 Hot Sample Process 100.0 97.3 86.3 64.4 36.4 18.7 7.1 5.074/17/2007 Hot Sample Process 100.0 96.7 86.7 60.0 31.1 16.3 6.3 4.774/17/2007 Hot Sample Process 100.0 97.3 87.8 58.1 31.2 15.9 6.1
18 18 18 18 18 18 18 14100.0 98.4 88.9 62.6 32.6 16.6 6.35 5.010.0 1.2 3.1 3.8 2.5 1.6 0.94 0.16
MeanStandard Deviation
Min RequirementMax RequirementMix Design Targets
Number
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Some States Do Not Allow RAP. Why?
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Conclusions
Do we need a mix design?Do we need to consider the properties of RAP?Guidelines
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Questions
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