1

Types, Properties and Grades of Asphalt-Part B

2

PG Specifications

Fundamental properties related to pavement performance

Environmental factors In-service & construction temperaturesShort and long term aging

3

Superpave Asphalt Binder Specification

The grading system is based on Climate

PG 64 - 22

Performance Grade

Average 7-day max pavement temperature

Min pavement temperature

4

Temperatures

Superpave Weather Database– 6500 stations in U.S. and Canada

Annual air temperatures– hottest seven-day temp (avg and std dev)– coldest temp (avg and std dev)

Calculated pavement temps used in PG selection:– High temperature

20 mm below the surface of mixture

– Low temperature at surface of mixture

> 20 years

SHRPA-648A

Pave temp = f (air temp, depth, latitude)

5

Superpave Tests

FatigueCracking

Rutting

RTFOShort Term Aging

No aging

Construction

[RV] [DSR]

Low TempCracking

[BBR]

[DTT][DTT]

PAVLong Term Aging

6

RV

DSR BBR

Construction

Tests Used in PG Specifications

7

Concentric Cylinder

Concentric Cylinder Rheometers

8

Rotational Viscometer (Brookfield)

Inner Cylinder

Torque Motor

Thermosel Environmental

Chamber

Digital Temperature Controller

9

.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

10

RV

DSR

BBR

Original Properties, Rutting, and Fatigue

11

DSR Equipment

DSR Equipment

Computer Control and Data

Acquisition

12

Area for Liquid Bath

Motor

Parallel Plates with Sample

13

25 mm Plate with Sample

14

Dynamic Shear Rheometer (DSR)

Parallel Plate

151 cycle

TimeAA

B

C

CA

B

Fixed Plate

Oscillating Plate

Test operates at 10 rad/secor 1.59 Hz

360o = 2 radiansper circle1 rad = 57.3o

16

Elastic Viscous

TimeA

A

B

C

Strain

Strain in-phase = 0o

Strain out-of-phase = 90o

17

Viscous Modulus, G”

Storage Modulus, G’

Complex Modulus, G*

Complex Modulus is the vector sum of the storage and viscous modulus

18

Short Term Binder Aging0

Rolling Thin Film Oven– Simulates aging from hot mixing and construction

19

Inside of RTFO

Fan

Air Line

Rotating Bottle

Carriage

20

Permanent Deformation

Addressed by:

G*/sin on unaged binder > 1.00 kPa

G*/sin on RTFO aged binder > 2.20 kPa

For the early part of the service life

21

Question: Why a minimum G*/sin to address rutting

Answer: We want a stiff, elastic binder to contribute to mix rutting resistance

How: By increasing G* or decreasing

Permanent Deformation

22

RV

DSR

BBR

Fatigue

23

Fatigue Cracking

Function of repeated traffic loads over time(in wheel paths)

24

Testing

Aged binder– Since long term performance problem, include:

Short term aging Long term aging

Determine DSR parameters using 8 mm plate and intermediate test temperature

25

Pressure Aging Vessel(Long Term Aging)

Simulates aging of an asphalt binder for 7 to 10 years

50 gram sample is aged for 20 hours Pressure of 2,070 kPa (300 psi) At 90, 100 or 110 C

26

Bottom of pressure aging

vessel

Rack of individual pans(50g of asphalt / pan)

Pressure Aging Vessel

Vessel Lid Components

27

Pressure Aging Vessel

Courtesy of FHWA

28

Fatigue Cracking

G* (sin G* (sin ) on RTFO and PAV aged binder) on RTFO and PAV aged binder

The parameter addresses the later part of the The parameter addresses the later part of the fatigue lifefatigue life

Value must be Value must be < < 5000 kPa 5000 kPa

29

Fatigue Cracking

Question: Why a maximum G* sin to address fatigue?

Answer: We want a soft elastic binder (to sustain many loads without cracking)

How: By decreasing G* or decreasing

30

RV DSRBBR

Thermal Cracking

31

Bending Beam Rheometer

Air Bearing

Load Cell

Deflection Transducer

Fluid Bath

Computer

32

Bending Beam Rheometer Sample

33

Bending Beam Rheometer Equipment

Cooling System

Fluid BathLoading

Ram

34

Bending Beam Rheometer

S(t) = P L3

4 b h3 (t)

Where:S(t) = creep stiffness (M Pa) at time, tP = applied constant load, NL = distance between beam supports (102 mm)b = beam width, 12.5 mmh = beam thickness, 6.25 mmd(t) = deflection (mm) at time, t

35

Bending Beam Rheometer

Evaluates low temperature stiffness properties– Creep stiffness– Slope of response (called m-value)

8 15 30 60 120 240

Log Creep Stiffness, S(t)

Log Loading Time, t (sec)

36

Is Stiffness Enough?

No. Need to assess strain needed to break specimen.– Thermal cracking occurs when strain is too great

Direct tension test– Currently (1998) in specification

New equipment is now available

37

Direct Tension Test

Le

L

Load

Stress = = P / A

Strainf

f

38

FHWA

Direct Tension Test

Courtesy of FHWA

39

Direct Tension Test

Courtesy of FHWA

40

Summary

FatigueCrackingRutting

RTFOShort Term AgingNo aging

Construction

[RV] [DSR]

Low TempCracking

[BBR]

[DTT][DTT]

PAVLong Term Aging

41

PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82

(Rotational Viscosity) RV

90 90 100 100 100 (110) 100 (110) 110 (110)

(Flash Point) FP

46 52 58 64 70 76 82

46 52 58 64 70 76 82

(ROLLING THIN FILM OVEN) (ROLLING THIN FILM OVEN) RTFO RTFO Mass Loss Mass Loss << 1.00 % 1.00 %

(Direct Tension) DT

(Bending Beam Rheometer) BBR Physical Hardening

28

-34 -40 -46 -10 -16 -22 -28 -34 -40 -46 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -10 -16 -22 -28 -34

Avg 7-day Max, oC

1-day Min, oC

(PRESSURE AGING VESSEL) (PRESSURE AGING VESSEL) PAVPAV

ORIGINALORIGINAL

> 1.00 kPa

< 5000 kPa

> 2.20 kPa

S < 300 MPa m > 0.300

Report Value

> 1.00 %

20 Hours, 2.07 MPa

10 7 4 25 22 19 16 13 10 7 25 22 19 16 13 31 28 25 22 19 16 34 31 28 25 22 19 37 34 31 28 25 40 37 34 31

(Dynamic Shear Rheometer) DSR G* sin

( Bending Beam Rheometer) BBR “S” Stiffness & “m”- value

-24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

-24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

PPerformance erformance GGradesrades

(Dynamic Shear Rheometer) DSR G*/sin

(Dynamic Shear Rheometer) DSR G*/sin

< 3 Pa.s @ 135 oC

> 230 oC

CEC

42

PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82

(Rotational Viscosity) RV

90 90 100 100 100 (110) 100 (110) 110 (110)

(Flash Point) FP

46 52 58 64 70 76 82

46 52 58 64 70 76 82

(ROLLING THIN FILM OVEN) (ROLLING THIN FILM OVEN) RTFO RTFO Mass Loss Mass Loss << 1.00 % 1.00 %

(Direct Tension) DT

(Bending Beam Rheometer) BBR Physical Hardening

28

-34 -40 -46 -10 -16 -22 -28 -34 -40 -46 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -10 -16 -22 -28 -34

Avg 7-day Max, oC

1-day Min, oC

(PRESSURE AGING VESSEL) (PRESSURE AGING VESSEL) PAVPAV

ORIGINALORIGINAL

< 5000 kPa

> 2.20 kPa

S < 300 MPa m > 0.300

Report Value

> 1.00 %

20 Hours, 2.07 MPa

10 7 4 25 22 19 16 13 10 7 25 22 19 16 13 31 28 25 22 19 16 34 31 28 25 22 19 37 34 31 28 25 40 37 34 31

(Dynamic Shear Rheometer) DSR G* sin

( Bending Beam Rheometer) BBR “S” Stiffness & “m”- value

-24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

-24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

How the PG Spec WorksHow the PG Spec Works

(Dynamic Shear Rheometer) DSR G*/sin

(Dynamic Shear Rheometer) DSR G*/sin

< 3 Pa.s @ 135 oC

> 230 oC

CEC

58 64

Test TemperatureTest TemperatureChangesChanges

Spec RequirementSpec RequirementRemains ConstantRemains Constant

> 1.00 kPa

43

PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82

(Rotational Viscosity) RV

90 90 100 100 100 (110) 100 (110) 110 (110)

(Flash Point) FP

46 52 58 64 70 76 82

46 52 58 64 70 76 82

(ROLLING THIN FILM OVEN) (ROLLING THIN FILM OVEN) RTFO RTFO Mass Loss Mass Loss << 1.00 % 1.00 %

(Direct Tension) DT

(Bending Beam Rheometer) BBR Physical Hardening

28

-34 -40 -46 -10 -16 -22 -28 -34 -40 -46 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -10 -16 -22 -28 -34

Avg 7-day Max, oC

1-day Min, oC

(PRESSURE AGING VESSEL) (PRESSURE AGING VESSEL) PAVPAV

ORIGINALORIGINAL

< 5000 kPa

S < 300 MPa m > 0.300

Report Value

> 1.00 %

20 Hours, 2.07 MPa

10 7 4 25 22 19 16 13 10 7 25 22 19 16 13 31 28 25 22 19 16 34 31 28 25 22 19 37 34 31 28 25 40 37 34 31

(Dynamic Shear Rheometer) DSR G* sin

( Bending Beam Rheometer) BBR “S” Stiffness & “m”- value

-24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

-24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

Permanent DeformationPermanent Deformation

(Dynamic Shear Rheometer) DSR G*/sin

(Dynamic Shear Rheometer) DSR G*/sin

< 3 Pa.s @ 135 oC

> 230 oC

CEC

> 1.00 kPa

> 2.20 kPa •UnagedUnaged•RTFO AgedRTFO Aged

44

PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82

(Rotational Viscosity) RV

90 90 100 100 100 (110) 100 (110) 110 (110)

(Flash Point) FP

46 52 58 64 70 76 82

46 52 58 64 70 76 82

(ROLLING THIN FILM OVEN) (ROLLING THIN FILM OVEN) RTFO RTFO Mass Loss Mass Loss << 1.00 % 1.00 %

(Direct Tension) DT

(Bending Beam Rheometer) BBR Physical Hardening

28

-34 -40 -46 -10 -16 -22 -28 -34 -40 -46 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -10 -16 -22 -28 -34

Avg 7-day Max, oC

1-day Min, oC

(PRESSURE AGING VESSEL) (PRESSURE AGING VESSEL) PAVPAV

ORIGINALORIGINAL

> 1.00 kPa

> 2.20 kPa

S < 300 MPa m > 0.300

Report Value

> 1.00 %

20 Hours, 2.07 MPa

10 7 4 25 22 19 16 13 10 7 25 22 19 16 13 31 28 25 22 19 16 34 31 28 25 22 19 37 34 31 28 25 40 37 34 31

(Dynamic Shear Rheometer) DSR G* sin

( Bending Beam Rheometer) BBR “S” Stiffness & “m”- value

-24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

-24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

Fatigue Cracking

(Dynamic Shear Rheometer) DSR G*/sin

(Dynamic Shear Rheometer) DSR G*/sin

< 3 Pa.s @ 135 oC

> 230 oC

CEC

< 5000 kPa

PAV AgedPAV Aged

45

PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82

(Rotational Viscosity) RV

90 90 100 100 100 (110) 100 (110) 110 (110)

(Flash Point) FP

46 52 58 64 70 76 82

46 52 58 64 70 76 82

(ROLLING THIN FILM OVEN) RTFO Mass Loss < 1.00 %

(Direct Tension) DT

(Bending Beam Rheometer) BBR Physical Hardening

28

-34 -40 -46 -10 -16 -22 -28 -34 -40 -46 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -10 -16 -22 -28 -34

Avg 7-day Max, oC

1-day Min, oC

(PRESSURE AGING VESSEL) PAV

ORIGINAL

> 1.00 kPa

< 5000 kPa

> 2.20 kPa

20 Hours, 2.07 MPa

10 7 4 25 22 19 16 13 10 7 25 22 19 16 13 31 28 25 22 19 16 34 31 28 25 22 19 37 34 31 28 25 40 37 34 31

(Dynamic Shear Rheometer) DSR G* sin

( Bending Beam Rheometer) BBR “S” Stiffness & “m”- value

-24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

-24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

Low Temperature Cracking

(Dynamic Shear Rheometer) DSR G*/sin

(Dynamic Shear Rheometer) DSR G*/sin

< 3 Pa.s @ 135 oC

> 230 oC

CEC

S < 300 MPa m > 0.300

Report Value

> 1.00 %

PAV Aged

46

PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82

(Rotational Viscosity) RV

90 90 100 100 100 (110) 100 (110) 110 (110)

(Flash Point) FP

46 52 58 64 70 76 82

46 52 58 64 70 76 82

(ROLLING THIN FILM OVEN) RTFO Mass Loss < 1.00 %

(Direct Tension) DT

(Bending Beam Rheometer) BBR Physical Hardening

28

-34 -40 -46 -10 -16 -22 -28 -34 -40 -46 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -10 -16 -22 -28 -34

Avg 7-day Max, oC

1-day Min, oC

(PRESSURE AGING VESSEL) PAV

ORIGINAL

> 1.00 kPa

< 5000 kPa

> 2.20 kPa

20 Hours, 2.07 MPa

10 7 4 25 22 19 16 13 10 7 25 22 19 16 13 31 28 25 22 19 16 34 31 28 25 22 19 37 34 31 28 25 40 37 34 31

(Dynamic Shear Rheometer) DSR G* sin

( Bending Beam Rheometer) BBR “S” Stiffness & “m”- value

-24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

-24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

Low Temperature Cracking

(Dynamic Shear Rheometer) DSR G*/sin

(Dynamic Shear Rheometer) DSR G*/sin

< 3 Pa.s @ 135 oC

> 230 oC

CEC

S < 300 MPa m > 0.300

Report Value

> 1.00 %

PAV Aged

47

PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82

(Rotational Viscosity) RV

90 90 100 100 100 (110) 100 (110) 110 (110)

(Flash Point) FP

46 52 58 64 70 76 82

46 52 58 64 70 76 82

(ROLLING THIN FILM OVEN) RTFO Mass Loss < 1.00 %

(Direct Tension) DT

(Bending Beam Rheometer) BBR Physical Hardening

28

-34 -40 -46 -10 -16 -22 -28 -34 -40 -46 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -40 -10 -16 -22 -28 -34 -10 -16 -22 -28 -34

Avg 7-day Max, oC

1-day Min, oC

(PRESSURE AGING VESSEL) PAV

ORIGINAL

> 1.00 kPa

< 5000 kPa

> 2.20 kPa

S < 300 MPa m > 0.300

Report Value

> 1.00 %

20 Hours, 2.07 MPa

10 7 4 25 22 19 16 13 10 7 25 22 19 16 13 31 28 25 22 19 16 34 31 28 25 22 19 37 34 31 28 25 40 37 34 31

(Dynamic Shear Rheometer) DSR G* sin

( Bending Beam Rheometer) BBR “S” Stiffness & “m”- value

-24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

-24 -30 -36 0 -6 -12 -18 -24 -30 -36 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 -30 0 -6 -12 -18 -24 0 -6 -12 -18 -24

Miscellaneous Spec Requirements

(Dynamic Shear Rheometer) DSR G*/sin

(Dynamic Shear Rheometer) DSR G*/sin

CEC

< 3 Pa.s @ 135 oC

> 230 oCFlashPoint

MassLoss

48

Summary of How to Use PG Specification

Determine – 7-day max pavement temperatures– 1-day minimum pavement temperature

Use specification tables to select test temperatures

Determine asphalt cement properties and compare to specification limits