03-Properties of Asphalt Traditional ( Highway and Airport Engineering Dr. Sherif El-Badawy )

1. 1
Properties of Asphalt Binder
General Asphalt Binder Properties
• Adheres well to most rock
• Waterproof
• Fairly durable
• Resistant to reaction with most acids,
alkalis, and salts
• Temperature sensitive

2. 2
Binder Performance is affected by:
• Temperature
• Rate of Loading
• Aging
60 C
25 C
1 hour
1 hour
Time vs. Temperature
10 hours
Time-Temperature Superposition

3. 3
Temperature Susceptibility
Temperature, °C
Stiffness (Response to Load)
-30 25 60 135
elastic
viscous
elastic
solid
viscous
fluid
At High
Tmp. Or
Slow
TrucksAt Low
Tmp. Or
fast Trucks
Temperature Susceptibility
Log Temperature
Too brittle (Thermal cracking)
Too soft (Rutting)
Optimum range
Of viscosity
LogLog(Viscosity)

4. 4
Temperature Susceptibility
Log Temperature
Soft
LogLog(Viscosity)
Hard
Soft asphalt is used in cold climates
Hard asphalt is used in hot climates
Effect of Rate of Loading

5. 5
Material Models
(Yoder and Witczak, 1974)
Aging Behavior
• Causes
Oxidation
Volatilization
Physical hardening
• Types
Short-term aging
Long-term aging

6. 6
Modified Asphalt
Asphalt properties can be improved with
polymer and other modifiers
Temperature susceptibility
Adhesion to aggregates (Reduce Stripping)
Resistance to permanent deformation
Resistance to fatigue cracking
Elasticity, ductility, and durability
Traditional Tests:
1 Penetration test
2 Ring and Ball Softening Point test
3 Absolute Viscosity test
4 Kinematic Viscosity test
Flash Point test
Performance Grade (Superpave) tests:
1 Rotational Viscometer (Brookfield) test
2 Dynamic Shear Rheometer (DSR) test
3 Bending Beam Rheometer (BBR) test
4 Direct Tension (DT) test
5 Rolling Thin Film Oven (RTFO) test
6 Pressure Aging Vessel (PAV) test
7 Flash Point test
Characterization of Asphalt Binder

7. 7
Classification of Asphalt Cement
• Based on penetration
• Based on viscosity
• Based on viscosity after aging
• Based on performance (Superpave)
Penetration Specifications

8. 8
Penetration Test
100g
100g
penetration
0 sec 5 sec
Penetration Specification
Five Grades
• 40 - 50
• 60 - 70
• 85 - 100
• 120 - 150
• 200 - 300
Maximum penetration
Minimum penetration

9. 9
Penetration Gradation Specification
• Uses penetration results to specify
• Adds
– Flash point test
– Ductility
– Solubility
– Thin film oven aging
• Penetration
• Ductility
Flash Point (Safety)
Thermometer
Cup filled with
asphalt binder
Wand attached
to gas line

10. 10
Ductility
Solubility (Purity)

11. 11
Thin Film Oven
Outside of Oven Rotating Shelf
Pan Thermometer
163 oC oven for 5 hours.
Classical Penetration- Based Specification
Min Max Min Max Min Max Min Max Min Max
Penetration @ 77°F(25°C) 100g, 5s 40 50 60 70 85 100 120 150 200 300
Flash Point, °F (Cleveland open cup) 450 --- 450 --- 450 --- 425 --- 350 ---
Ductility at 77°F (25°C) 5cm/min, cm 100 --- 100 --- 100 --- 100 --- 100A ---
Solubility in trichloroethylene, % 99 --- 99 --- 99 --- 99 --- 99 ---
Retained penetration after thin-film 55+ --- 52+ --- 47+ --- 42+ --- 37+ ---
oven test, %
Ductility at 77°F (25°C) 5cm/min, cm --- --- 50 --- 75 --- 100 --- 100A ---
after thin-film oven test
40-50 60-70 85-100 120-150 200-300
Penetration Grade
A If ductility at 77°F (25°C) is less than 100 cm, material will be accepted if ductility at 60°F (15.5°C) is 100 cm minimum
at the pull rate of 5 cm/min

12. 12
Temperature
25C (77F)
High
Medium
Low
Advantages of Penetration
Specifications
• Grades asphalt binders near average in-service
temp.
• Fast
• Can be used in field labs
• Low cost of Equipment
• Precision well established
• Temp. susceptibility can be determined

13. 13
Disadvantages
• Empirical test
• Shear rate
– High
– Variable
• Mixing and compaction temperature information not
available
• Similar penetrations at 25C (77F) do not reflect wide
differences in asphalts
Viscosity Graded Specifications

14. 14
Viscosity: is defined as the resistance of the
material to flow.
Viscosity: is the ratio between the applied
shear stress and the rate of shear strain.
h = t / g
Definition
Units of Viscosity
• Pa.S = Pascal. Second
• cS = Centi Stoke
• cP = Centi Poise
• P = Poise
Pa.S = 1000 cP
P = 100 cP
Stoke = 100 cS
cS = cP / Gb

15. 15
Viscosity Tests
vacuum
CANNONCANNON
100100
A9A9
Timing
Marks
Viscometers
Absolute Viscosity Test
• Absolute viscosity
– U-shaped tube with
timing marks & filled
with asphalt binder
– Placed in 60C bath
– Vacuum used to pull
asphalt through tube
– Time to pass marks
– Visc. in Pa s (Poise)

16. 16
Kinematic Viscosity Test
• Kinematic viscosity
– Cross arm tube with timing
marks & filled with asphalt
– Placed in 135C bath
– Once started gravity moves
asphalt through tube
– Time to pass marks
– Visc. in mm2 / s (centistoke)
Viscosity Grade Specifications
• Viscosities at 60 and 135oC
• Penetrations at 25oC
• Flash point
• Solubility
• TFO aged residue
– Viscosity at 60oC
– Ductility at 25oC

17. 17
AC Grades (Viscosity Grades)
AC-2.5, AC-5, AC-10
AC-20, AC-30, AC-40
AC- # 1/100 of midpoint of the
allowable viscosity range.
AC-20, viscosity range
1,600 to 2,400 poises.
Asphalt cement
AC Grades Example
AC 2.5 AC 40
Visc, 60C 250 + 50 4,000 + 800
Visc, 135C 80+ 300+
Penetration 200+ 20+
Visc, 60C <1,250 <20,000
Ductility 100+ 10+

18. 18
Log Temperature
25C (77F) 60C (140F) 135C (275F)
Ave.
Service
Temp.
Mixing
&
Compaction
Hot
Summer
LogLogViscosity(Stiffness)
Advantages of (Original AC Visc. Grade)
• Fundamental property
• Wide range of temperatures
• Based on max. pavement surface temp.
• Wide range of instruments
• Test method precision established
• Temperature susceptibility is controlled
• Limits aging
• Information on mixing & compaction temps.

19. 19
Disadvantages
(Original AC Visc. Grade)
• More expensive
• Longer testing time
• More technician skill needed
• Not applicable for Non-Newtonian materials
• Wide range of properties for same grade
Viscosity After Aging Graded
Specifications

20. 20
AR Grades
AR-10, AR-20, AR-40
AR-80, AR-160
AR- # 1/100 of midpoint of
viscosity after aging.
AR-40, viscosity range
3,000 to 5,000 poises.
Aged Residue
AR Grades Specifications
• AR Grades
– AR 1000, AR 2000, AR 4000,
AR 8000, AR 16000
• Tests on RTFO aged residue
– Viscosities at 60 and 135oC
– Penetrations at 25oC
– % of Original Penetration
– Ductility
– Properties of unaged asphalt
binders
• Flash point and solubility

21. 21
Fan
Air Line
Rotating
Bottle
Carriage
BeforeAfter
Rolling Thin Film Oven Test (RTFOT)
163oC in Oven, for
80 minutes
Advantages
(AR Visc. Grade)
• Represents asphalt binder properties after
mixing
• Fundamental properties
• Covers wide range of temperatures
• Limits aging

22. 22
Disadvantages
(AR Visc. Grade)
• Highly regional
• Requires different testing equipment
• Longer testing time
• No consistency test on original Asphalt Binder
• Not applicable for Non-Newtonian materials
• Wide range of properties for same grade
40
50
60
70
85
100
120
150
200
300
Penetration Grades
AC 40
AC 20
AC 10
AC 5
AC 2.5
100
50
10
5
Viscosity,60C(140F)
AR 16000
AR 8000
AR 4000
AR 2000
AR 1000
Comparison of the Various Traditional
Specifications

23. 23
Mixing and Compaction Temperatures
– MS-2
• Recommended laboratory mixing and compaction
temperature ranges for Marshall mix design based on
viscosity (Saybolt Furol) as early as 1962.
– Changed to absolute and kinematic viscosity in 1974.
– 170 ± 20 centipoise for mixing
– 280 ± 30 centipoise for compaction
– Purpose
• Normalize the effect of asphalt binder stiffness on
mixture volumetric properties
– Aggregate packing and available void space
Log Temperature, R
LogLogViscosity,cP
Compaction Range
Mixing Range
Mixing/Compaction Temps

24. 24
Ai-VTSi
Temperature - Viscosity Relationship for:
PG 64-22, Tank Condition
y = -3.8785x + 11.519
R2
= 0.992
0.0
0.2
0.4
0.6
0.8
1.0
1.2
2.70 2.75 2.80 2.85 2.90 2.95
Log (Temp) (R)
LogLog(Visc)(cP)
Background
• Modified Asphalt Binders in the Superpave Mix
Design System
• Adopted old (Marshall) standard in 1993
– 170 ± 20 centipoise for mixing
– 280 ± 30 centipoise for compaction
• Manufacturer’s recommendation for
modified asphalt binders:
- based on PG grade
- based on field experience