SuperpaveTM Asphalt Grading

CIVL 3137 2

Asphalt Cement Performance

ElasticSolid

TrueLiquid

ViscoelasticSolid

ViscousLiquid

PenetrationNumber

AbsoluteViscosity

KinematicViscosity

AverageServiceTemp

MaximumServiceTemp

MixingPlacingTemp

MinimumServiceTemp

0ºF 275ºF77ºF 140ºF

Traditional Grading

Viscosity (cP)

200-300 400-600 800-1200 1600-2400 3200-4800

46 52 58 64 70 76 8260

Temperature (°C)

Performance Grading

Dynamic Shear Modulus (kPa)

46 52 58 64 70 76 82

Temperature (°C)

0 0.5 1 1.5 2

CIVL 3137 5

• Uses fundamental physical and mechanical properties, not index properties

• Performance-based: criteria remain constant but the test temperature changes

• Lowest 1-day single temperature

• Highest 7-day average temperature

• Explicitly addresses aging, thermal cracking, fatigue cracking and rutting

Superpave Grading

CIVL 3137 6

Superpave GradingEquipment Purpose

Rotational Viscometer Properties at construction temps

Dynamic Shear Rheometer Properties at high service temps

Rolling Thin-Film Oven Aging due to volatilization

Pressure Aging Vessel Aging due to oxidation

Bending Beam Rheometer Properties at low service temps

Direct Tension Tester Properties at low service temps

CIVL 3137 7

Performance Grading

CIVL 3137 8

Performance Grading

CIVL 3137 9

Can be usedwith modifiedor unmodifiedbinders w/outclogging

20 rpm

Rotational Viscometer

The viscosity of the unaged binder must be less than 3000 cPat 135ºC for good pumping and mixing

CIVL 3137 10

Viscosity of Common LiquidsWater 1 centipoise

Cream 20 centipoise

Vegetable Oil 100 centipoise

Tomato Juice 200 centipoise

Honey 2000 centipoise

Chocolate Syrup 10000 centipoise

Sour Cream 20000 centipoise

Ketchup 50000 centipoise

Peanut Butter 150000 centipoise

Vegetable Shortening 1000000 centipoise

CIVL 3137 11

Rotational Viscometer

CIVL 3137 12

AppliedStress

1.59 Hz

time

App

lied

Stre

ss

Dynamic Shear Rheometer

Fixed plate46oC to 82oC

CIVL 3137 13

Dynamic Shear Rheometer

CIVL 3137 14

Dynamic Shear Rheometer

time

Stre

ss

time

Stra

in

Elastic Solid = 0 deg

time

Stre

ss

time

Stra

inViscous Liquid = 90 deg

CIVL 3137 15

Dynamic Shear Rheometer

time

Stre

ss

time

Stra

in

t

max

min

max

min

max min

max min

*G

t f

CIVL 3137 16

Dynamic Shear Rheometer

AppliedStress

Fixed plate

G*/sin of unaged binder must exceed1.00 kPa at the high service temperature to prevent rutting

CIVL 3137 17

Rolling Thin-Film Oven

325oF

AirJet

SampleBottle

Simulates aging of asphalt cement during mixing and laydown

85 min

CIVL 3137 18

Rolling Thin Film Oven

CIVL 3137 19

Dynamic Shear Rheometer

AppliedStress

Fixed plate

G*/sin of the stiffer RTFO-aged binder must exceed 2.2 kPa at the high service temperature to prevent rutting

CIVL 3137 20

90-110oC

samplepan

air

300 psi

Pressure Aging Vessel

20 hours

Simulates aging of asphalt cement over years due to oxidation

CIVL 3137 21

Dynamic Shear Rheometer

AppliedStress

Fixed plate

G* sin of the stiffer PAV-aged binder must be less than 5000 kPa at the mean of the high and low service temperatures to prevent fatigue cracking

CIVL 3137 22

P

D

t

Bending Beam Rheometer

Fluid Bath

Air Bearing

100 g

0ºC to -36oC

CIVL 3137 23

P

D

t

Bending Beam Rheometer

3

34P t LS tbh D t

Creep Stiffness

CIVL 3137 24

Bending Beam Rheometer

CIVL 3137 25

Bending Beam Rheometer

CIVL 3137 26

Bending Beam Rheometer

Fluid Bath

Air Bearing

100 g

0ºC to -36oC

S(t) of the PAV-aged binder must not exceed 300 MPa after 2 hours at the low service temperature to prevent thermal cracking

CIVL 3137 27

efff L

L

Direct Tension Tester

Leff Leff + L

0ºC to -36oC

CIVL 3137 28

Direct Tension Test

CIVL 3137 30

Direct Tension Tester

f of the PAV-aged binder must exceed 1% at the low service temperature to prevent thermal cracking

CIVL 3137 32

Superpave Grading

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

HighGrades

–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

LowGrades

PG 64–22

TypicalPerformance

Grade

CIVL 3137 33

Superpave Grading

PG 64 -22“Performance

Grade”Maximum7-day avg.pavement

temperature

Minimum1-day

pavementtemperture

CIVL 3137 34

Superpave Grade Selection

767064585246-4-10-16-22-28

Lowest 1-dayAir Temperature

Highest 7-day avg.Air Temperature

403428

Based on Historical Weather Recordsat the Project Location

CIVL 3137 35

Superpave Grade Selection

767064585246-4-10-16-22-28Lowest 1-day

PavementTemperature

Highest 7-day avg.Pavement

Temperature

Based on Empirical RelationshipsBetween Air and Pavement Temperature

403428

CIVL 3137 36

Superpave Grade Selection

767064585246-4-10-16-22-28

PG70-22

PG64-16

Lowest 1-dayPavement

Temperature

Highest 7-day avg.Pavement

Temperature

Normal Probability Distribution

CIVL 3137 37

Standard Deviations

CIVL 3137 38

Superpave Grade Selection

767064585246-4-10-16-22-28

PG70-22

PG64-16

Lowest 1-dayPavement

Temperature

Highest 7-day avg.Pavement

Temperature

Normal Probability Distribution

CIVL 3137 39

56 58 60 62 64 66 68

PG64-16

Temperature (°C)

16%84%

CIVL 3137 40

Superpave Grade Selection

767064585246-4-10-16-22-28

Reliability = (0.84)(0.70) = 59%

PG64-16

~30% ~16%~70% ~84%

Lowest 1-dayPavement

Temperature

Highest 7-day avg.Pavement

Temperature

CIVL 3137 41

Superpave Grade Selection

767064585246-4-10-16-22-28

PG70-22

Reliability = (1.00)(0.98) = 98%

~2% ~0%~98% ~100%

Lowest 1-dayPavement

Temperature

Highest 7-day avg.Pavement

Temperature

CIVL 3137 42

Superpave Binder Grades

82-40

82-34

82-28

82-22

82-16

82High Temperature, °C

CIVL 3137 43

Superpave Binder Cost

$662.50 $717.50$570.50

82

$775.00

High Temperature, °C

Cost per ton based on TDOT reimbursement rates for October 2012

Grade Bumping

CIVL 3137 45

PG 64-22 PG 70-22 PG 76-22 PG 70-22

CIVL 3137 46