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Asphalt Binders History and Background 1
Asphalt Binders
Background
History of Specifications
Senior/GraduateHMA Course
Background
First US Hot Mix Asphalt (HMA) constructed in 1870’s– Pennsylvania Ave.– Used naturally
occurring asphalt binders from surface of lake on Island of Trinidad
Two sources– Island of Trinadad– Bermudez, Venezuela
Asphalt Binder History and Background 3
Asphalt Binder History and Background 4
Asphalt Binder History and Background 5
Background
Each lake asphalt source very consistent – Used solubility test to determine source
» Insolubles differed substantially between sources
Demand for paved roads exceeded the supply of lake asphalts in late 1800’s– Led to use of petroleum asphalts binders
Asphalt Binder History and Background 6
Asphalt Binder History and Background 7
Petroleum-Based Asphalt Binders Asphalt binder is waste product from refinery
processing of crude oil– Sometimes called the “bottom of the barrel”
Properties depend on:– Refinery operations– Composition crude source-dependent
GasolineKerosene
Lt. Gas OilDiesel
Motor Oils
Asphalt
Barrel of Crude Oil
Asphalt Binder History and Background 8
Purchasing of Asphalt Binders
Need to be able to specify desirable characteristics “Desirable characteristics” have evolved over time
and with increasing technological advances
Purchasing requires specifications
Asphalt Binder History and Background 9
Early Specifications
Lake Asphalts– Appearance– Solubility in carbon disulfide
Petroleum asphalt binders (early 1900’s)– Consistency
»Chewing»Penetration machine
Measure consistency
Penetration Testing Sewing machine needle Specified load, time, temperature
100 g
Initial
Penetration in 0.1 mm
After 5 seconds
Asphalt Binder History and Background 11
Penetration Specification
Five Grades
• 40 - 50
• 60 - 70
• 85 - 100
• 120 - 150
• 200 - 300
Asphalt Binder History and Background 12
Penetration Gradation Specification
Uses penetration results to specify Adds
– Flash point test– Ductility– Solubility– Thin film oven aging
»Penetration»Ductility
Asphalt Binder History and Background 13
Flash Point (Safety)
Thermometer
Cup filled with asphalt binder
Wand attached to gas line
Asphalt Binder History and Background 14
Ductility
Asphalt Binder History and Background 15
Solubility (Purity)
Asphalt Binder History and Background 16
Thin Film Oven
Outside of Oven Rotating Shelf
Pan Thermometer
Asphalt Binder History and Background 17
Typical Penetration Specifications
Penetration 40 - 50 200 - 300
Flash Point, F 450+ 350+
Ductility, cm 100+ 100+
Solubility, % 99.0+ 99.0+
Retained Pen., % 55+ 37+
Ductility, cm NA 100+
Asphalt Binder History and Background 18
Temperature25C (77F)
Pen
etra
tio
n, 0
.1 m
m
High
Medium
Low
Asphalt Binder History and Background 19
Advantages
Grades asphalt binders near average in-service temp.
Fast Can be used in field labs Low capital costs Precision well established Temp. susceptibility can be determined
Asphalt Binder History and Background 20
Disadvantages
Empirical test Shear rate
– High– Variable
Mixing and compaction temp. information not available
Similar penetrations at 25C (77F) do not reflect wide differences in asphalts
Asphalt Binder History and Background 21
Viscosity Graded Specifications
Asphalt Binder History and Background 22
Viscosity: the ratio between the applied shear stress and the rate of shear.
Definition
Asphalt Binder History and Background 23
Types of Viscosity Tubes
Asphalt Institute TubeZietfuchs Cross-Arm
Tube
Asphalt Binder History and Background 24
Testing
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)
Asphalt Binder History and Background 25
Testing
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)
Asphalt Binder History and Background 26
Viscosity Grade Specifications
ASTM D3381 Three specifications
– Table 1»Original properties
– Table 2»Original properties
– Table 3»Rolling thin film oven aging
Asphalt Binder History and Background 27
Table 1 & 2 Tests
Viscosities at 60 and 135oC Penetrations at 25oC Flash point Solubility TFO aged residue
– Viscosity at 60oC– Ductility at 25oC
Asphalt Binder History and Background 28
Table 1 & 2 Grades
Table 1 – AC 2.5, AC 5, AC 10, AC 20, AC 40
Table 2– AC 2.5, AC 5, AC 10, AC 20, AC 30, AC 40
Asphalt Binder History and Background 29
Table 1 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+
Asphalt Binder History and Background 30
Table 2 Example
AC 2.5AC 2.5 AC 40AC 40
Visc, 60CVisc, 60C 250 250 ++ 50 50 4,000 4,000 ++ 800 800
Visc, 135CVisc, 135C 125+ 125+ 400+ 400+
PenetrationPenetration 220+ 220+ 40+ 40+
Visc, 60CVisc, 60C <1,250<1,250 <20,000 <20,000
DuctilityDuctility 100+ 100+ 25+25+
Asphalt Binder History and Background 31
Temperature
25C (77F) 60C (140F) 135C (275F)
Ave. Service Temp.
Mixing &
Compaction
Hot Summer
Table 1
40 Pen
210
Table 2
60 Pen
300
Low2400
1600
Vis
cosi
ty (
Sti
ffn
ess)
Asphalt Binder History and Background 32
.1.1
.2.2
.3.3
.5.5
11
1010
55
100100 110110 120120 130130 140140 150150 160160 170170 180180 190190 200200
Temperature, CTemperature, C
Viscosity, Pa sViscosity, Pa s
Compaction RangeCompaction Range
Mixing RangeMixing Range
Mixing/Compaction Temps
Asphalt Binder History and Background 33
Advantages (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.
Asphalt Binder History and Background 34
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
Asphalt Binder History and Background 35
Table 3
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
Asphalt Binder History and Background 36
Rolling Thin Film Oven
Asphalt Binder History and Background 37
Table 3 Specification
AR 1000AR 1000 AR 16,000 AR 16,000
Visc, 60C 1,000 Visc, 60C 1,000 ++ 250 16,000 250 16,000 ++ 4,000 4,000
Visc, 135CVisc, 135C 140+ 140+ 550+ 550+
Pen.Pen. 65+ 65+ 20+ 20+
% Orig. Pen% Orig. Pen NS NS 52+ 52+
Asphalt Binder History and Background 38
Advantages (AR Visc. Grade)
Represents asphalt binder properties after mixing
Fundamental properties Covers wide range of temperatures Limits aging
Asphalt Binder History and Background 39
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
Asphalt Binder History and Background 40
4050
6070
85100
120150
200300
Penetration Grades
AC 40
AC 20
AC 10
AC 5
AC 2.5
100
50
10
5
Vis
cosi
ty,
60C
(14
0F)
AR 16000
AR 8000
AR 4000
AR 2000
AR 1000
Asphalt Binder History and Background 41
QUESTIONS?