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1
Asphalt 101:
An Introduction to Hot Mix Asphalt
Materials
-Part I-
Asphalt and Modified Asphalts
1
Asphalt 101:
An Introduction to Hot Mix Asphalt
Materials
-Part I-
Asphalt and Modified Asphalts
Scott Shuler
CSU
2
2
Glue:Scott Shuler
Sticky Glue:Marshall Shackelford
3
Why Study Asphalt?
3
Why Study Asphalt?
of all the ROADS IN THE U. S. A.(miles)
3
Why Study Asphalt?
of all the ROADS IN THE U. S. A.(miles)
Concrete Earth Gravel Asphalt
100,000
3
Why Study Asphalt?
of all the ROADS IN THE U. S. A.(miles)
Concrete Earth Gravel Asphalt
100,000 400,000
3
Why Study Asphalt?
of all the ROADS IN THE U. S. A.(miles)
Concrete Earth Gravel Asphalt
100,000 400,000
1,300,000
3
Why Study Asphalt?
of all the ROADS IN THE U. S. A.(miles)
Concrete Earth Gravel Asphalt
100,000 400,000
1,300,000
2,200,000
95%5%
4
Why Study Asphalt?
4
Why Study Asphalt?
Highway Expenditures in 2008– $140 Billion
4
Why Study Asphalt?
Highway Expenditures in 2008– $140 Billion
Hot Mix Asphalt Placed Annually– 500 Million Tons– $10.5 Billion
4
Why Study Asphalt?
Highway Expenditures in 2008– $140 Billion
Hot Mix Asphalt Placed Annually– 500 Million Tons– $10.5 Billion
Employment– 300,000 directly– 600,000 additionally
4
Why Study Asphalt?
Highway Expenditures in 2008– $140 Billion
Hot Mix Asphalt Placed Annually– 500 Million Tons– $10.5 Billion
Employment– 300,000 directly– 600,000 additionally
Asphalt is Largely Empirical– “Old Timers” Retiring
5
What Are Asphalt Pavements ?
5
What Are Asphalt Pavements ?
Rocks Glued Together With Asphalt
5
What Are Asphalt Pavements ?
Rocks Glued Together With Asphalt
5
What Are Asphalt Pavements ?
Rocks Glued Together With Asphalt
About 86% n Rocks Volume
5
What Are Asphalt Pavements ?
Rocks Glued Together With Asphalt
About 86%
About 10%
n Rocks
n Asphalt
Volume
5
What Are Asphalt Pavements ?
Rocks Glued Together With Asphalt
About 86%
About 10%
4%
n Rocks
n Asphalt
n Air
Volume
6
Let’s Consider the Glue
6
Among the Oldest Engineering Materials– Waterproofing of Ships
Sumeria-6000 BC
Let’s Consider the Glue
6
Among the Oldest Engineering Materials– Waterproofing of Ships
Sumeria-6000 BC– Waterproofing of Baths and Tanks “Earth Butter”
Mohenjo-Daro Indus Valley-3000 BC
Let’s Consider the Glue
6
Among the Oldest Engineering Materials– Waterproofing of Ships
Sumeria-6000 BC– Waterproofing of Baths and Tanks “Earth Butter”
Mohenjo-Daro Indus Valley-3000 BC– Mummies
Egypt-2600 BC
Let’s Consider the Glue
6
Among the Oldest Engineering Materials– Waterproofing of Ships
Sumeria-6000 BC– Waterproofing of Baths and Tanks “Earth Butter”
Mohenjo-Daro Indus Valley-3000 BC– Mummies
Egypt-2600 BC
– Bible References Noah’s Arc Waterproofed with “Pitch” Genesis 6:14.20 Moses’ Basket Coated with “Bitumen” and “Pitch” Exodus 2:3.24
Let’s Consider the Glue
6
Among the Oldest Engineering Materials– Waterproofing of Ships
Sumeria-6000 BC– Waterproofing of Baths and Tanks “Earth Butter”
Mohenjo-Daro Indus Valley-3000 BC– Mummies
Egypt-2600 BC
– Bible References Noah’s Arc Waterproofed with “Pitch” Genesis 6:14.20 Moses’ Basket Coated with “Bitumen” and “Pitch” Exodus 2:3.24
– Roman Buildings Waterproofed and Cemented Romans called the source Lacus Asphaltites
Let’s Consider the Glue
7
So It Will Work!
7
So It Will Work!
7
So It Will Work!
7
So It Will Work!
8
Reed Boat, aka Gufa
9
9
Bitumen
9
Bitumen
Asphalts Tars
9
Bitumen
Asphalts Tars
PetroleumNatural Coal
10
Asphalts
10
Asphalts
PetroleumNatural
10
Asphalts
PetroleumNatural
Lake
10
Asphalts
PetroleumNatural
LakeTrinidad
10
Asphalts
PetroleumNatural
LakeTrinidad
La Brea
10
Asphalts
PetroleumNatural
Lake
Rock
Trinidad
La Brea
10
Asphalts
PetroleumNatural
Lake
Rock
Trinidad
La Brea
KY
10
Asphalts
PetroleumNatural
Lake
Rock
Trinidad
La Brea
KY
TX
10
Asphalts
PetroleumNatural
Lake
Rock
Trinidad
La Brea
KY
TX
AB
10
Asphalts
PetroleumNatural
Lake
Rock
Asphaltites
Trinidad
La Brea
KY
TX
AB
10
Asphalts
PetroleumNatural
Lake
Rock
Asphaltites
Trinidad
La Brea
KY
TX
AB
UT-Gilsonite
10
Asphalts
PetroleumNatural
Lake
Rock
Asphaltites
Cements LiquidsTrinidad
La Brea
KY
TX
AB
UT-Gilsonite
10
Asphalts
PetroleumNatural
Lake
Rock
Asphaltites
Cements Liquids
Emulsions Cutbacks
Trinidad
La Brea
KY
TX
AB
UT-Gilsonite
11
Crude Oil Variations
11
Crude Oil Variations
Venezuelan Nigerian Light
11
Crude Oil Variations
Gasoline 3%
Venezuelan
Gasoline 33%
Nigerian Light
11
Crude Oil Variations
Gasoline 3%Kerosene 6%
Venezuelan
Gasoline 33%
Kerosene 20%
Nigerian Light
11
Crude Oil Variations
Gasoline 3%Kerosene 6%
Gas Oil 33%
Venezuelan
Gasoline 33%
Kerosene 20%
Gas Oil 46%
Nigerian Light
11
Crude Oil Variations
Gasoline 3%Kerosene 6%
Gas Oil 33%
Residuum 58%
Venezuelan
Gasoline 33%
Kerosene 20%
Gas Oil 46%
Residuum 1%
Nigerian Light
12
Refining Methods
12
Refining Methods
Distillation– Atmospheric– Vacuum
12
Refining Methods
Distillation– Atmospheric– Vacuum
Solvent Deasphalting– Propane and Butane Extraction of Lube Oils– Result is Very Hard Precipitate AC
12
Refining Methods
Distillation– Atmospheric– Vacuum
Solvent Deasphalting– Propane and Butane Extraction of Lube Oils– Result is Very Hard Precipitate AC
Solvent Extraction (ROSE)– Separates AC into Asphaltenes/Resins/Oils– Result is Blended to Produce Spec AC
13
Petroleum Asphalts
13
Petroleum Asphalts
Oil Well
13
Petroleum Asphalts
CrudeStorage
Oil Well
13
Petroleum Asphalts
CrudeStorage
Oil Well
Atm
os S
till
60-700F
13
Petroleum Asphalts
CrudeStorage
Oil Well
Atm
os S
till
Con
dens
er
60-700F
13
Petroleum Asphalts
CrudeStorage
GasolineKerosene
Oil Well
Atm
os S
till
Con
dens
er
60-700F
60-325F
325-500F
13
Petroleum Asphalts
CrudeStorage
GasolineKerosene
Oil Well
Atm
os S
till
Con
dens
er
60-700F
60-325F
325-500F
13
Petroleum Asphalts
CrudeStorage
GasolineKerosene
Vacu
um S
till
Oil Well
Atm
os S
till
Con
dens
er
60-700F
60-325F
325-500F
13
Petroleum Asphalts
CrudeStorage
GasolineKerosene
Gas Oil
Vacu
um S
till
Oil Well
Atm
os S
till
Con
dens
er
650-1050F60-700F
60-325F
325-500F
650-850F
13
Petroleum Asphalts
CrudeStorage
GasolineKerosene
Gas Oil
Vacu
um S
till
AsphaltCements
Oil Well
Atm
os S
till
Con
dens
er
650-1050F60-700F
60-325F
325-500F
650-850F
13
Petroleum Asphalts
CrudeStorage
GasolineKerosene
Gas Oil
Vacu
um S
till
AsphaltCements
Emulsions
Oil Well
Atm
os S
till
Con
dens
er
H 2O
650-1050F60-700F
60-325F
325-500F
650-850F
13
Petroleum Asphalts
CrudeStorage
GasolineKerosene
Cutbacks
Gas Oil
Vacu
um S
till
AsphaltCements
Emulsions
Oil Well
Atm
os S
till
Con
dens
er
H 2O
Gas/Kero650-1050F60-700F
60-325F
325-500F
650-850F
13
Petroleum Asphalts
CrudeStorage
GasolineKerosene
Cutbacks
Gas Oil
Vacu
um S
till
AsphaltCements
Emulsions
Oil Well
Atm
os S
till
Con
dens
er
H 2O
RoofingAsphalts
Air
Gas/Kero650-1050F60-700F
60-325F
325-500F
650-850F
14
Asphalt Types
14
Asphalt Types
Asphalt Cement
14
Asphalt Types
Asphalt Cement Liquid Asphalts
– Emulsified Asphalts– Cutback Asphalts
15
Behavior of Asphalt Cements
15
Behavior of Asphalt Cements
Asphalt is Viscoelastic– Viscous (Flows) at High Temperatures
15
Behavior of Asphalt Cements
Asphalt is Viscoelastic– Viscous (Flows) at High Temperatures– Elastic at Low Temperatures
15
Behavior of Asphalt Cements
Asphalt is Viscoelastic– Viscous (Flows) at High Temperatures– Elastic at Low Temperatures
Silly Putty is Viscoelastic– Pull it Slowly- It stretches – same as high temperature
15
Behavior of Asphalt Cements
Asphalt is Viscoelastic– Viscous (Flows) at High Temperatures– Elastic at Low Temperatures
Silly Putty is Viscoelastic– Pull it Slowly- It stretches – same as high temperature– Pull it Rapidly – It breaks – same as low temperature
16
Asphalt Performance depends
on Environment and Traffic
16
Asphalt Performance depends
on Environment and Traffic
17
17
Hot
Beh
avio
r
17
Weak BehaviorH
ot B
ehav
ior
17
Weak BehaviorH
ot B
ehav
ior
Cold Behavior
18
Temperature Effects
18
Temperature Effects
100°F
1 Hour
18
Temperature Effects
30°F
100°F
1 Hour
18
Temperature Effects
30°F
100°F
1 Hour
10 Hours
18
Temperature Effects
30°F
100°F
1 Hour
10 Hours
19
Material Effects
19
Material Effects
30°F
1 Hour
19
Material Effects
30°F
1 Hour
Hard Asphalt Softer Asphalt
20
20
Achieving
20
SUPERPAVE
To The Rescue !
20
SUPERPAVE
To The Rescue !
21
SPECIFYING PERFORMANCE
Based on Climate
21
SPECIFYING PERFORMANCE
Based on Climate
PG 64 - 22
21
SPECIFYING PERFORMANCE
Based on Climate
PG 64 - 22
Performance Grade
21
SPECIFYING PERFORMANCE
Based on Climate
PG 64 - 22
Performance Grade
Average 7-day max pavement temperature, C
21
SPECIFYING PERFORMANCE
Based on Climate
PG 64 - 22
Performance Grade
Average 7-day max pavement temperature, C
Min pavement temperature, C
22
Dynamic Shear
Rheometer
Tests in PG Specifications
Bending Beam
Rheometer
Rotational Viscometer
23
Caused by Warm Weather, Traffic and Wrong Mixture
Cou
rtes
y of
FH
WA
Permanent Deformation ( )
24
High Temperature or,Slow Loading Behavior, aka Rutting
High Pavement Temperature– Desert climates– Summer temperatures
Sustained loads– Slow moving trucks– Intersections
24
High Temperature or,Slow Loading Behavior, aka Rutting
High Pavement Temperature– Desert climates– Summer temperatures
Sustained loads– Slow moving trucks– Intersections
100°F
1 Hour
25
Courtesy of FHWA
Thermal Cracking
Caused by Low Temperatures, Rapid Loads, Hard Binder
26
Low Temperature, or Fast Loading Behavior-aka Cracking
26
Low Temperature, or Fast Loading Behavior-aka Cracking
Low Temperature– Cold climates– Winter
26
Low Temperature, or Fast Loading Behavior-aka Cracking
Low Temperature– Cold climates– Winter
Rapid Loads– Fast moving trucks
26
Low Temperature, or Fast Loading Behavior-aka Cracking
Low Temperature– Cold climates– Winter
Rapid Loads– Fast moving trucks
σ
ε
26
Low Temperature, or Fast Loading Behavior-aka Cracking
Low Temperature– Cold climates– Winter
Rapid Loads– Fast moving trucks
σ
ε
Cracking Failure
27
Aging
Asphalt reacts with oxygen– Becomes harder, more brittle– More Elastic, Less Viscous
Short term– During Mixing with Aggregates (280F-330F)
Long term– In Pavement– Air, Water, Sun
28
Asphalt Plant and Construction Aging
Rolling Thin Film Oven (RTFO)
Fan
Rotating Bottle
Carriage
Blowing Air
29
Pressure Aging Vessel
Pressure Aging Vessel
29
Pressure Aging Vessel
50 grams of Asphalt in Each Pan
Pressure Aging Vessel
30
Pressure Aging Vessel
Courtesy of FHWA
31
RV
DSR
BBR
Rutting, Hardening and Fatigue
32
1 cycle
32
1 cycle
Fixed Lower Plate
32
1 cycle
Fixed Lower Plate
Oscillating Upper Plate
32
1 cycle
CA
B
Fixed Lower Plate
Oscillating Upper Plate
32
1 cycle
CA
B
Fixed Lower Plate
Oscillating Upper PlateAsphalt Glued In-Between
32
1 cycle
Time
CA
B
Fixed Lower Plate
Oscillating Upper PlateAsphalt Glued In-Between
32
1 cycle
TimeAA
B
C
CA
B
Fixed Lower Plate
Oscillating Upper Plate
A
Asphalt Glued In-Between
32
1 cycle
TimeAA
B
C
CA
B
Fixed Lower Plate
Oscillating Upper Plate
A
Now, Measure the Force Required to Rotate the Upper
Plate
And, Measure When Movement Occurs in
the Binder
Asphalt Glued In-Between
33
33
Elastic
Time
33
Elastic
TimeAA
B
C
Strain
Strain Occurs With Stressδ = 0o
A
Stress
33
Elastic Viscous
TimeAA
B
C
Strain
Strain Occurs With Stressδ = 0o
A
Stress
33
Elastic Viscous
TimeAA
B
C
Strain
Strain Occurs With Stressδ = 0o
AA
B
C
AA
Stress
33
Elastic Viscous
TimeAA
B
C
Strain
Strain Occurs With Stressδ = 0o
Strain Lags Stressδ = 90o
AA
B
C
AA
Stress
34
δ
34
Elastic, G’
δ
34
Vis
cous
, G”
Elastic, G’
δ
34
Vis
cous
, G”
Elastic, G’
Complex M
odulus, G*
δ
Complex Modulus is the vector sum of
Elastic and Viscous Components
35
> Early part of pavement lifeHeavy Trucks
Controlling Rutting
35
> Early part of pavement lifeHeavy Trucks
Controlling RuttingAddressed by: G*/sin δ on Unaged binder > 1.00 kPa G*/sin δ on Lab Aged binder > 2.20 kPa
36
Fatigue Cracking
36
Caused by repeated traffic loads in wheel pathsFatigue Cracking
37
Fatigue Cracking
Addressed by intermediate temperature stiffness– G*sin δ on RTFO & PAV
aged binder < 5000 kPa
> Later part of pavement service life
38
RV DSR BBR
Thermal Cracking
39
Bending Beam Rheometer
Load Cell
Deflection Transducer
Fluid Bath
Computer
40
BBR Measures Stiffness at Low Temperatures using Beam Theory
40
BBR Measures Stiffness at Low Temperatures using Beam Theory
S(t) =PL3
4 bh3 δ (t)
Creep stiffness at
t = 60 secs
40
BBR Measures Stiffness at Low Temperatures using Beam Theory
S(t) =PL3
4 bh3 δ (t)
Creep stiffness at
t = 60 secs100 grams
40
BBR Measures Stiffness at Low Temperatures using Beam Theory
S(t) =PL3
4 bh3 δ (t)
Creep stiffness at
t = 60 secs100 grams
Clear Span of Beam, 102 mm
40
BBR Measures Stiffness at Low Temperatures using Beam Theory
S(t) =PL3
4 bh3 δ (t)
Creep stiffness at
t = 60 secs100 grams
Clear Span of Beam, 102 mm
Beam Width, 12.5 mm
Beam Thickness, 6.25 mm
40
BBR Measures Stiffness at Low Temperatures using Beam Theory
S(t) =PL3
4 bh3 δ (t)
Creep stiffness at
t = 60 secs100 grams
Clear Span of Beam, 102 mm
Beam Width, 12.5 mm
Beam Thickness, 6.25 mm
Deflection at t = 60 secs
41
Bending Beam Rheometer
41
Bending Beam Rheometer Creep Stiffness Stiffness v. Time Slope
41
Bending Beam Rheometer Creep Stiffness Stiffness v. Time Slope
8 15 30 60 120 240
Log
Cre
ep
Stif
fnes
s, S
(t)
Log Loading Time, t (sec)
41
Bending Beam Rheometer Creep Stiffness Stiffness v. Time Slope
8 15 30 60 120 240
Log
Cre
ep
Stif
fnes
s, S
(t)
Log Loading Time, t (sec)
41
Bending Beam Rheometer Creep Stiffness Stiffness v. Time Slope
8 15 30 60 120 240
Log
Cre
ep
Stif
fnes
s, S
(t)
Log Loading Time, t (sec)
41
Bending Beam Rheometer Creep Stiffness Stiffness v. Time Slope
8 15 30 60 120 240
Log
Cre
ep
Stif
fnes
s, S
(t)
Log Loading Time, t (sec)
41
Bending Beam Rheometer Creep Stiffness Stiffness v. Time Slope
8 15 30 60 120 240
Log
Cre
ep
Stif
fnes
s, S
(t)
Log Loading Time, t (sec)
m
41
Bending Beam Rheometer Creep Stiffness Stiffness v. Time Slope
8 15 30 60 120 240
Log
Cre
ep
Stif
fnes
s, S
(t)
Log Loading Time, t (sec)
m
42
Thermal Cracking
Question: How Much Should the Asphalt Be Able to Stretch before Breaking?
42
Thermal Cracking
Question: How Much Should the Asphalt Be Able to Stretch before Breaking?
Answer: at least 1%
How: Find the Temperature Where the Asphalt Can Stretch 1% or More
43
Direct Tension Test
Δ Le
43
Direct Tension Test
Δ Le
43
Direct Tension Test
Δ Le
Δ L
Load
43
Direct Tension Test
Δ Le
Δ L
Load
Strain εf
σf
43
Direct Tension Test
Δ Le
Δ L
Load
Strain εf
σf
43
Direct Tension Test
Δ Le
Δ L
Load
Stress = σ = P / A
Strain εf
σf
44
RVDynamic
Shear Rheometer
ConstructionBut Will it Flow for Mixing ?
Bending Beam
Rheometer
Rotational Viscometer
45
Rotational Viscometer (Brookfield)
Inner Cylinder
Torque Motor
Thermosel Environmental
Chamber
Digital Temperature Controller
46
Spec Requirements
Make Sure It’s Not Too Thick– Keep Viscosity Below 3 Pa-sec at 275F (135C)
47