Optimization of Asphalt Mix Design and

Construction with Special Polymers

Professor Hussain BahiaUniversity of Wisconsin-Madison

Moscow, Russia

March 26-27, 2015

Outline

• The need for Bitumen Modification

• Effect of Modification on

– Bitumen properties using Superpave and other methods

– Constructability of asphalt mixtures

– Rutting and cold temperature cracking testing.

• Using digital imaging to show how some polymers can

cause better packing of aggregates

• Potential savings of material, energy, and longer

pavement life cycle

3

Refineries Are not Designed to Improve Bitumen

FIELD STORAGE PUMPING

STATION

LIGHT DISTILLATE

HEAVY DISTILLATE

PROCESS

UNIT

Bitumen

FOR PROCESSING INTO

EMULSIFIED AND

CUTBACKs

STILL

AIR

AIR

BLOWN

Bitumen

STORAGE

TOWER

DISTILLATION

REFINERY

RESIDUUM

OR

GAS

PETROLEUM

SAND AND WATER

CONDENSERS

AND

COOLERS

TUBE

HEATER

MEDIUM DISTILLATE

Bitumen Role in Road Construction -Performance Based Grading

•Constructability

•Performance

•Durability

Rutting

Fatigue Cracking

Thermal Cracking

Polymers for Asphalt

5

6

Modification Targets

• Polymer interacts with the asphalt to produce a more durable pavement

– Elastomers Or Plastomers (FPE)

Elastomer

PEF

Modification can Improve Bitumen BehaviorsHardness and Visco-elasticity

Hard

Soft

Elastic Viscous

Lower TempShorter loading time(High Traffic Speed)

Higher TempLonger loading timeSlower Traffic Speed

Thermal

Cracking

Fatigue

Cracking

Permanent

Deformation

(mixing &

compact)

Pavement Temperature, C

RTFO

- 20 20 60 135

PAV

RuttingFatigue CrackingThermal Cracking Production

Fundamental Rheology Tests – PG System

Modification by Changing PG Grades

9

64

67

70

73

76

Base PE1 PE2 PE3 PE4

HT

Co

nti

nu

ou

s G

rad

e (

C) asphalt 1 asphalt 2

PE1, PE2= NA, PEs PE3,PE4=European PEs -28

-22

-16

Base PE1 PE2 PE3 PE4

LT

Co

nti

nu

ou

s G

rad

e (

C)

asphalt 1 asphalt 2PG 64 – 22 >> PG 70-22

PG Grades and Binder Modification

Modification with Polymers

Modifi-

cation

with

Oils

The New Grading System- MP19 –PG xx(z)-yy

1. Climate: xx-yy2. Traffic conditions- Trucks (S,H,V,E)3. Reliability , and4. Modification

PG 64(V)-10Performance

Grade Summer

Average 7-day

max pavement

design temp

Winter

Min pavement

design temp

Traffic

Volume &

Speed

Effect of Modifier on Aggregate Structure : Rocks + Asphalt + Air Voids

Stability of HMA:

1.Rock- to – rock contacts

2.Binder rheology

13

Polymers can Change Viscosity vs. Temperature

100

1,000

10,000

100,000

100 110 120 130 140 150 160 170

Lo

g V

isc

os

ity

(cP

s)

Temperature °C

PG 64-22 Base Asphalt Additized to PG 76-22

E

OxPE

E +OxPE

PE Does not Change Viscosity

Workability Gyrations to 92% Density

0

5

10

15

20

25

E E+OxPE OxPE

N9

2 135 °C

110 °C

Polymers can improves workability

15

Moisture Sensitivity-(AASHTO T283, +EN12697-11)

0

0.2

0.4

0.6

0.8

1

1.2

E1 E+OxPE OxPE

Rati

o o

f C

on

dit

ioned

(W

et)

/ U

nco

nd

itio

ned

(D

ry)

Neat With Anti-Strip

Reduces or eliminates need for Anti-Strip

additives

•Tensile Strength Ratio*

•All Compositions Additized to PG 76-22

3% E

3% OxPE

•Boiling Water Test**

**North West Russian Granite Aggregate

•Dorservis Russian lab test shows increased

adhesion to granite

*Evaluation completed in collaboration with Modified Asphalt Research Center –

MARC at Univ. of Wisconsin Madison

Wheel Tracking Test-(EN 12697-22)Test: water 50°C, steel wheel, 20000 cycles

Binders used in SMA 8S:

P1: PmB 45A (E)

P2: PmB 45A

(E+OxPE)

P3: PmB 45C (OxPE)

16

Rutting Resistance - EN 12697-22

With Hybrid formulation, rutting reduced by ~50%.

Pen 35/50

(E1)

Pen

50/70

Pen 35/50

(E2)

Pen 35/50

(E+OxPE)

Pen 35/50

(OxPE)

SpecBBSG 0/10

Cl 3

30000 cycles

@ 60°C air3.4 5.1 4.2 2.2 3.1 < 5,0

Typical Flow Number(FN) curves

OxPE

Rutting Resistance – Flow Number (AASHTO TP79)

E E+OxPE

18

Thermal Stress Restrained Specimen Test (TSRST)

Ashalt Thermal

Cracking Analyzer(ATCA)

E+OxPE

Control

OxPE

E

αg

αl

Tg

19

Good correlation between Internal Structure Parameters

and Coefficient of Thermal Expansion.

Increase in Total Proximity Length

Higher Connectivity of Aggregate Skeleton

Higher Resistance to Thermal Strain

Effect of Aggregate Structure on CTCAggregate Structure Parameters

R² = 0.90 R² = 0.97

4.50E-05

4.70E-05

4.90E-05

5.10E-05

5.30E-05

5.50E-05

5.70E-05

5.90E-05

6.10E-05

0 1000 2000 3000 4000 5000

αl (1

/°C

)

Total Proximity Length (mm/100 cm2)

Fine

Coarse

20

Concluding Results

• Roads are built with mixtures, not Binders!

• Roads’ Cracking & rutting are affected by:

– aggregate structure and bitumen Properties.

• There are many modifiers that can improve road

performance. The best are those that can improve:

Workability

Packing of aggregates at reasonable construction temperatures

Moisture resistance

Low and high temperature performance

• There could be significant savings of cost, energy

and increase in service life of roads

Thank You!

www.uwmarc.org

Questions?

Hussain Bahiabahia@engr.wisc.edu