04-Superpave Binder Testing ( Highway and Airport Engineering Dr. Sherif El-Badawy )

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

Superpave Asphalt Binder Specification

Superpave=Superior Performing Asphalt Pavement

New Superpave Binder Specifications

Intended to improve pavement performance by

reducing the potential to:

Permanent deformation

Fatigue cracking

Low-temperature cracking

Excessive aging from volatilization

Pumping and handling

Superpave Asphalt Binder Specification

PG 64-22

PerformanceGrade

Average 7-daymax pavementdesign temp

Min pavementdesign temp

Grading system and selection based primarily on climate

(NHI, 2002)

Pavement Temperatures are Calculated

• Calculated by Superpave software

• High temperature

– 20 mm below the surface of mixture

• Low temperature

– at surface of mixture

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

www.fhwa.gov/pavement/ltpp/ltppbind.htm

http://www.tfhrc.gov/pavement/ltpp/ltppbind.htm

PG Specification Tests

• Rheology• Fundamental properties related to HMA

performance

• Test parameters• Selected to represent in-service & construction

temperatures

• Asphalt binder conditioning• Environmental factors

• Short and long term aging

Superpave Specification (Cont’d)

• Superpave specification attempts to measure

properties that are directly related to pavement

field performance

Handling

Pump

Permanent

Deformation

Fatigue

Cracking

Thermal

Cracking

Flow

Rutting

Structural Cracking

Low Temp Cracking

Rotational Viscometer

Dynamic Shear Rheometer

Bending Beam Rheometer

Direct Tension Tester

TEST EQUIPMENTPERFORMANCE PROPERTY

Superpave Binder Equipment

Fatigue

CrackingRutting

PAV - aging

RTFO - aging No aging

Pavement Age

Construction

[RV][DSR]

Low Temp

Cracking

[BBR]

[DTT]

Superpave Binder Equipment

Pavement Temperature, C

- 20 20 60 135

DTT

BBR

DSR

RV

Rotational Viscometer

spindle

torque

sample

sample

chamber

(Brookfield Viscosity)

http://www.pavementinteractive.org/article/rotational-

viscometer/

Construction Asphalt Binder

Properties

• Concentric cylinder rheometer• Used to insure a minimum workability

(pumpability) at typical mixing temperature

• Maximum viscosity 3kPa at 135oC

Construction

[RV]

RV

DSR

BBR

Rutting

Short Term Aging

• Simulates stiffening of asphalt binder

during storage, mixing, and lay down

• Function of:

• Oxidation hardening

• Asphalt binder reacts with oxygen

• Volatilization of specific components

• Simulated using rolling thin film oven

(RTFO)


Applied Stress

Fixed Plate

Asphalt

Oscillating

Plate

B CA

Position of

Oscillating Plate

A

B

A

C

A

Time

1 cycle


height (h)

radius (r)

torque (T)

deflection angle ()

DSR

http://www.pavementinteractive.org

/article/dynamic-shear-rheometer/

http://www.pavementinteractive.org/article/dynamic-shear-rheometer/

Elastic vs. Viscous Behaviors

time

time

Elastic: = 0 deg Viscous: = 90 deg

max

max

max max

time lag = t

Applied

Shear

Stress

Resulting

Shear

Strain

Viscoelastic: 0 < < 90 o

Resulting

Shear

Strain

Applied

ShearStress

max

tt = time lag

time

time

max

G* = max

max

Rutting

• High in-service temperature

• Desert climates

• Summer temperatures

• Sustained loads

• Slow moving trucks

• Intersections

Viscous Liquid

Function of warm

weather and traffic

Rutting

Superpave DSR test requirements:

G*/sin on unaged (original) asphalt binder > 1.00 kPa

G*/sin on RTFO aged asphalt binder > 2.20 kPa

We want a stiff, elastic asphalt binder

to resist rutting (for the early part of the

service life)

(By increasing G* or decreasing )

RV

DSR

BBR

Fatigue

Fatigue Cracking

Function of repeated traffic loads over time

(in wheel paths)

DSR

• Aged PG asphalt binder

• Since long term performance

problem, include:

• Short term aging

• Long term aging

• Determine DSR parameters using

8 mm plate and intermediate test

temperature

Fatigue

Cracking

[DSR]

Long Term Aging

• Simulates aging of an PG asphalt binder for 7

to 10 years

• Starts with RTFO aged PG asphalt binder

– Additional aging with Pressure Aging Vessel

(PAV)

PAV Components

Bottom of

pressure

aging

vessel

Rack of individual

pans

(50g of asphalt / pan)

Vessel Lid Components

PAV Testing

• After RTFO aging

– 50 gram sample/pan aged for 20 hours in PAV

• Pressure of 2,070 kPa (300 psi)

• Test temp 90, 100 or 110o C

http://www.pavementinteractive.org

/article/pressure-aging-vessel/

Equipment Examples

www.prentex.com

Fatigue Cracking

• G* (sin ) on RTFO and PAV aged asphalt

binder

• The parameter addresses the later part of the

fatigue life

• Value must be < 5,000 kPa

We want a soft elastic asphalt binder to

sustain many loads without cracking

(By decreasing G* or decreasing )

RVDSR

BBR

Thermal

Cracking


- 20 20 60 135

DTT

BBR

DSR

RV

DTT

Low Temperature Behavior

• Low Temperature

• Cold climates

• Winter

• Rapid Loads

• Fast moving trucks

Elastic Solid

Thermal Cracking

Courtesy of FHWA

Low Temperature

• Two tests

• Direct tension

• Strength

• Bending beam

• Stiffness

Low Temp

Cracking

[BBR]

[DTT]


aluminum mold

plastic strips

Rubber O-rings

127 mm

6.35 mm

12.7 mm

asphalt beam


Fluid Bath

DeflectionTransducer

Load Cell

Asphalt Beam

Air Bearing

Loading

Frame

Supports

Control andData Acquisition

Thermometer

http://www.pavementinteractive.org/arti

cle/bending-beam-rheometer/


RVDSR

BBR

Thermal

Cracking


- 20 20 60 135

DTT

BBR

DSR

RV

DTT

Direct Tension Tester

L

Load

L+ L

L

failure strain ( f) =

effective length (L )

change in length ( L)

eL

e

f

stress

strain

f

http://www.pavementinteractive.org/article/direct-tension-tester/

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

Superpave Binder Specifications

(Dynamic Shear Rheometer) DSR G*/sin

(Dynamic Shear Rheometer) DSR G*/sin

< 3 Pa.s @ 135 oC

> 230 oC

CEC