asphalt 104: an introduction to hot mix asphalt materials
TRANSCRIPT
1
Asphalt 104:
An Introduction to Hot Mix Asphalt
Materials
-Part II-
Mix Design
Scott ShulerCSU
2
The MIX
2
The MIX
n Rocks
2
The MIX
n Rocks
n Asphalt
2
The MIX
n Rocks
n Asphalt
2
The MIX
n Rocks
n Asphalt
n Air
2
The MIX
About 86% n Rocks
n Asphalt
n Air
2
The MIX
About 86% n Rocks
n Asphalt
n Air
2
The MIX
About 86%
About 10%
n Rocks
n Asphalt
n Air
2
The MIX
About 86%
About 10%
n Rocks
n Asphalt
n Air
2
The MIX
About 86%
About 10%
4%
n Rocks
n Asphalt
n Air
2
The MIX
About 86%
About 10%
4%
n Rocks
n Asphalt
n Air
3
3
Purpose of Mixture Design
3
To Build Better Roads
4
4
Better Asphalt Roads are:
4
Better Asphalt Roads are:
Coarse
Medium
Fine
A Combination of an Asphalt Binder
And Crushed Rocks
5
5
These Individual Rock Sizes Will Not Make a Good Asphalt Mix Alone
but
A Combination Might
Coarse
Medium
Fine
6
What Combination Works?
Coarse Intermediate Fines
6
What Combination Works?
Coarse Intermediate Fines
33.3% 33.3% 33.3%
7
Maximum Density for Aggregates
Goode and Lufsey, Bureau of Public Roads
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Maximum Density for Aggregates
Goode and Lufsey, Bureau of Public Roads
p = 100
d
D
0.45
7
Maximum Density for Aggregates
Goode and Lufsey, Bureau of Public Roads
p = 100
d
D
0.45 p = percent material passing a given sieve d
D = Maximum aggregate size
8
Aggregate Gradation Specs
0.075 0.30 2.36 4.75 9.5 12.5 19.0
Sieve Sizes Raised to 0.45 Power
Perc
ent P
assi
ng
100
Maxsize
Nommaxsize
controlpoints
maximum density line
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9
What a Mixture Design Does
9
What a Mixture Design Does
Creates a Strong Pavement – HOW?
9
What a Mixture Design Does
Creates a Strong Pavement – HOW?– The Right Volumes of
9
What a Mixture Design Does
Creates a Strong Pavement – HOW?– The Right Volumes of
n Rocks
9
What a Mixture Design Does
Creates a Strong Pavement – HOW?– The Right Volumes of
n Rocks
9
What a Mixture Design Does
Creates a Strong Pavement – HOW?– The Right Volumes of
About 86% n Rocks
9
What a Mixture Design Does
Creates a Strong Pavement – HOW?– The Right Volumes of
About 86% n Rocks
9
What a Mixture Design Does
Creates a Strong Pavement – HOW?– The Right Volumes of
About 86% n Rocks
n Asphalt
9
What a Mixture Design Does
Creates a Strong Pavement – HOW?– The Right Volumes of
About 86% n Rocks
n Asphalt
9
What a Mixture Design Does
Creates a Strong Pavement – HOW?– The Right Volumes of
About 86%
About 10%
n Rocks
n Asphalt
9
What a Mixture Design Does
Creates a Strong Pavement – HOW?– The Right Volumes of
About 86%
About 10%
n Rocks
n Asphalt
9
What a Mixture Design Does
Creates a Strong Pavement – HOW?– The Right Volumes of
About 86%
About 10%
n Rocks
n Asphalt
n Air
9
What a Mixture Design Does
Creates a Strong Pavement – HOW?– The Right Volumes of
About 86%
About 10%
4%
n Rocks
n Asphalt
n Air
9
What a Mixture Design Does
Creates a Strong Pavement – HOW?– The Right Volumes of
About 86%
About 10%
4%
n Rocks
n Asphalt
n Air
10
10
Traffic Affects the Air Voids
10
Rocks
Traffic Affects the Air Voids
10
Rocks
Traffic Affects the Air Voids
86%
10
Rocks
Traffic Affects the Air Voids
Asphalt
86%
10
Rocks
Traffic Affects the Air Voids
Asphalt
86%
10%
10
Rocks
Traffic Affects the Air Voids
Asphalt
86%
10%
Air
10
Rocks
Traffic Affects the Air Voids
Asphalt
86%
10%
Air 4%
10
Rocks
Traffic Affects the Air Voids
Asphalt
86%
10%
Air 4%
10
Rocks
Traffic Affects the Air Voids
Asphalt
86%
10%
Air 4%
Minivans, Cars
10
Rocks
Traffic Affects the Air Voids
Asphalt
86%
10%
Air 4%
Minivans, Cars
Heavier Traffic Squeezes Air Out
10
Rocks
Traffic Affects the Air Voids
Asphalt
86%
10%
Air 4%
Minivans, Cars
Heavier Traffic Squeezes Air Out
Air 3%
Light Trucks, Vans
10
Rocks
Traffic Affects the Air Voids
Asphalt
86%
10%
Air 4%
Minivans, Cars
Heavier Traffic Squeezes Air Out
Air 3%
Light Trucks, Vans
Until There is Less, and Less
10
Rocks
Traffic Affects the Air Voids
Asphalt
86%
10%
Air 4%
Minivans, Cars
Heavier Traffic Squeezes Air Out
Air 3%
Light Trucks, Vans
2%
Semis
Until There is Less, and Less
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And Finally…..
11
And Finally…..
Rutting
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Rocks
Asphalt
86%
10%
Air 4%
CarsLight Trucks Semis
Adjust Asphalt and Rocks for Traffic
4%4%
9% 8%
88%87%
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Simulate Traffic in the Laboratory
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Simulate Traffic in the Laboratory
Low Gyrations - Cars
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Simulate Traffic in the Laboratory
Low Gyrations - Cars
13
Simulate Traffic in the Laboratory
Low Gyrations - Cars
Med Gyrations – Lt Trucks
13
Simulate Traffic in the Laboratory
Low Gyrations - Cars
Med Gyrations – Lt Trucks
13
Simulate Traffic in the Laboratory
Low Gyrations - Cars
Med Gyrations – Lt Trucks
High Gyrations - Semis
13
Simulate Traffic in the Laboratory
Low Gyrations - Cars
Med Gyrations – Lt Trucks
High Gyrations - Semis
14
14
How Much Asphaltto get 4% Air Voids ??????
The Key to Mixture Design
14
Med Traffic-50
How Much Asphaltto get 4% Air Voids ??????
10
8
6
4
2
0
4.5 5.0 5.5 6.0 6.5
Air
Voi
ds, %
Asphalt, %
The Key to Mixture Design
14
Med Traffic-50
How Much Asphaltto get 4% Air Voids ??????
10
8
6
4
2
0
4.5 5.0 5.5 6.0 6.5
Air
Voi
ds, %
Asphalt, %
The Key to Mixture Design
14
Med Traffic-50
How Much Asphaltto get 4% Air Voids ??????
10
8
6
4
2
0
4.5 5.0 5.5 6.0 6.5
Air
Voi
ds, %
Asphalt, %
Low Traffic-35Hi Traffic-75
5.0 5.3
As Traffic Increases
The Key to Mixture Design
14
Med Traffic-50
How Much Asphaltto get 4% Air Voids ??????
10
8
6
4
2
0
4.5 5.0 5.5 6.0 6.5
Air
Voi
ds, %
Asphalt, %
Low Traffic-35Hi Traffic-75
5.0 5.3
As Traffic Increases
The Key to Mixture Design
14
Med Traffic-50
How Much Asphaltto get 4% Air Voids ??????
10
8
6
4
2
0
4.5 5.0 5.5 6.0 6.5
Air
Voi
ds, %
Asphalt, %
Low Traffic-35Hi Traffic-75
5.0 5.3
As Traffic Increases
The Key to Mixture Design
14
Med Traffic-50
How Much Asphaltto get 4% Air Voids ??????
10
8
6
4
2
0
4.5 5.0 5.5 6.0 6.5
Air
Voi
ds, %
Asphalt, %
Low Traffic-35Hi Traffic-75
5.0 5.3
As Traffic Increases
The Key to Mixture Design
14
Med Traffic-50
How Much Asphaltto get 4% Air Voids ??????
10
8
6
4
2
0
4.5 5.0 5.5 6.0 6.5
Air
Voi
ds, %
Asphalt, %
Low Traffic-35Hi Traffic-75
5.0 5.3 5.7
As Traffic Increases
Decreases
The Key to Mixture Design
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15
We Must Know TrafficTo Know Asphalt %
15
We Must Know TrafficTo Know Asphalt %
Let’s Design for Residential Streetwith 100 cars per day
15
We Must Know TrafficTo Know Asphalt %
Let’s Design for Residential Streetwith 100 cars per day
15
We Must Know TrafficTo Know Asphalt %
10
8
6
4
2
0
4.5 5.0 5.5 6.0 6.5
Air
Voi
ds, %
Asphalt, %
Let’s Design for Residential Streetwith 100 cars per day
15
We Must Know TrafficTo Know Asphalt %
10
8
6
4
2
0
4.5 5.0 5.5 6.0 6.5
Air
Voi
ds, %
Asphalt, %
Low Traffic-35
Let’s Design for Residential Streetwith 100 cars per day
15
We Must Know TrafficTo Know Asphalt %
10
8
6
4
2
0
4.5 5.0 5.5 6.0 6.5
Air
Voi
ds, %
Asphalt, %
Low Traffic-35
5.7
Let’s Design for Residential Streetwith 100 cars per day
16
Would this DesignWork on I-25??????
10
8
6
4
2
0
4.5 5.0 5.5 6.0 6.5
Air
Voi
ds, %
Asphalt, %
5.7
1.8
Low Traffic-35
16
Would this DesignWork on I-25??????
10
8
6
4
2
0
4.5 5.0 5.5 6.0 6.5
Air
Voi
ds, %
Asphalt, %
5.7
1.8
Hi Traffic-75
Low Traffic-35
16
Would this DesignWork on I-25??????
10
8
6
4
2
0
4.5 5.0 5.5 6.0 6.5
Air
Voi
ds, %
Asphalt, %
5.7
1.8NO!1.8% Air Voids Is Too Low
Hi Traffic-75
Low Traffic-35
16
Would this DesignWork on I-25??????
10
8
6
4
2
0
4.5 5.0 5.5 6.0 6.5
Air
Voi
ds, %
Asphalt, %
5.7
1.8NO!1.8% Air Voids Is Too Low
Hi Traffic-75
5.0
Decrease AC%
Low Traffic-35
17
Superpave Mix Design
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Superpave Mix Design
Gyratory Compactor Simulates Traffic Better Than Hammer
17
Superpave Mix Design
Gyratory Compactor Simulates Traffic Better Than Hammer
17
Superpave Mix Design
Gyratory Compactor Simulates Traffic Better Than Hammer
Volumetric Analysis (Voids)
17
Superpave Mix Design
Gyratory Compactor Simulates Traffic Better Than Hammer
Volumetric Analysis (Voids)
17
Superpave Mix Design
Gyratory Compactor Simulates Traffic Better Than Hammer
Volumetric Analysis (Voids)
Adjusts AC% to Traffic and Climate
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18
Volumetric Analysis
18
Volumetric Analysis
Air Voids
18
Volumetric Analysis
Air VoidsVMA (Voids in Mineral Aggregate
18
Volumetric Analysis
Air VoidsVMA (Voids in Mineral AggregateVMA Filled with AC%
18
Volumetric Analysis
Air VoidsVMA (Voids in Mineral AggregateVMA Filled with AC%Absorption
19
VMA Concept
19
VMA Concept
Durability – Enough Binder… Not Too Much
19
VMA Concept
Durability – Enough Binder… Not Too Much
About 86% n Rocks
19
VMA Concept
Durability – Enough Binder… Not Too Much
About 86%
About 10%
n Rocks
n Asphalt
19
VMA Concept
Durability – Enough Binder… Not Too Much
About 86%
About 10%
4%
n Rocks
n Asphalt
n Air
VMA = Effective Asphalt + Air
Voids are Just Full Enough
20
If VMA Too Low
20
If VMA Too Low
Durability Suffers…Not Enough Coating
About 88%
About 8%
4%
n Rocks
n Asphalt
n Air
VMA = Effective Asphalt + Air
Voids are Not Full Enough
21
If VMA Too High
21
If VMA Too High
Stability Suffers…Too Much Coating
About 84%
About 12%
4%
n Rocks
n Asphalt
n Air
VMA = Effective Asphalt + Air
Voids are Too Full of Asphalt
22
Select Asphalt and Aggregates
Aggregates
1. Coarse Aggregate Angularity (fractured faces)2. Fine Aggregate Angularity3. Flat and Elongated Particles4. Clay Content (sand equivalent)5. Toughness (LA Abrasion)6. Soundness7. Deleterious Stuff8. Gradation
23
Evaluate Compaction
Air
Void
s, %
0
Low Med HighCompaction
Ninit
Ndes
Nmax
11
5
2
3
24
StabilityPressure
Load
RubberAllows LateralMovement
25
Optimum AC%
25
Optimum AC%6
4
2
0
45
35
25
% Voids
Stability, %
4.5 5.0 5.5 6.0
minimum
25
Optimum AC%6
4
2
0
45
35
25
% Voids
Stability, %
4.5 5.0 5.5 6.0
minimum
25
Optimum AC%6
4
2
0
45
35
25
% Voids
Stability, %
4.5 5.0 5.5 6.0
minimum
25
Optimum AC%
5.3
6
4
2
0
45
35
25
% Voids
Stability, %
4.5 5.0 5.5 6.0
minimum
26
Verify 5.3% AC
26
Verify 5.3% AC
VMA OK?
26
Verify 5.3% AC
VMA OK?
26
Verify 5.3% AC
VMA OK?
VFA OK?
26
Verify 5.3% AC
VMA OK?
VFA OK?
26
Verify 5.3% AC
VMA OK?
VFA OK?
Stability OK?
26
Verify 5.3% AC
VMA OK?
VFA OK?
Stability OK?
26
Verify 5.3% AC
VMA OK?
VFA OK?
Stability OK?
Moisture Sensitivity OK?
27
Let’s Pave!
27
Let’s Pave!
28