preliminary studies on warm recycled mixtures for …

Canestrari F. & Stimilli A. 1

Polytechnic University of Marche – Faculty of Engineering

8th International RILEM SIB Symposium

Ancona, Italy, 06 - 09 October, 2015

6th October 2015

WARM RECYCLING OF ASPHALT MIXTURES: PRELIMINARY STUDIES ON WARM RECYCLED

MIXTURES FOR ITALIAN MOTORWAYS APPLICATIONS

Professor Francesco Canestrari & Arianna Stimilli, PhD

Polytechnic University of Marche – Ancona

Department of Civil and Building Engineering and Architecture

[email protected]; [email protected]





Problem Statement & Objectives

Experimental Program

Materials

Testing

Results & Analysis

Work in Progress

Conclusions

OUTLINE







Materials

Testing

Results & Analysis

Work in Progress

Conclusions

OUTLINE





Warm Recycling





High traffic volume

Continuous rehabilitation and maintenance activities

Huge amount of RAP

Lot of work for production plants

Narrow territory

Densely populated

Plants located near urban areas

Warm Recycling





Worries for EMISSIONS AND POLLUTION

especially when RAP is used (higher production T)

Huge amount of RAP available

Warm Recycling

“How can we reduce emissions and incorporate equal or increased amount of RAP

without significantly penalizing mixture performance??”





Step 1 Step 3Step 2







Materials

Testing

Results & Analysis

Work in Progress

Conclusions

OUTLINE





Materials

Which ADDITIVE??





Materials

0.5% by virgin

bitumen weight

3% by virgin

bitumen weight

0.3% by mix

weight

Chemical additive C

Organic additiveO

ZeoliteZ





Materials

TRADITIONAL HMA (standard T = 170°C and 160°C)

_H_H _H_H

BINDER (B)25% RAP + SBS

POROUS ASPHALT (PA)15% RAP + SBS

Chemical additive C

Organic additiveO

ZeoliteZ





Materials

WARM MIXES

(ADDITIVES + LOW T)

_WC_WC _WO_WO _WZ_WZ_H_H _WC_WC _WO_WO _WZ_WZ _H_H



Chemical additive C

Organic additiveO

ZeoliteZ





Materials



_WC_WC _WO_WO _WZ_WZ_W_W_H_H _WC_WC _WO_WO _WZ_WZ _W_W _H_H

WARM MIX

(NO ADDITIVES + LOW T)

Chemical additive C

Organic additiveO

ZeoliteZ





Materials

Which TEMPERATURE??





BITUMEN

Viscometer

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

90 110 130 150 170 190

LO

G(L

OG

(vis

co

sità

)) [

mP

a∙s

]

Temperature [°C]

Compactability

Equiviscosity Principle





100

120

140

160

180

200

WMA_C WMA_O WMA_Z

Mix

ing t

em

pe

raru

re[°

C]

HMA

Expected WMA

mixing

temperature

Compactability

Equiviscosity Principle





Materials

HMASTANDARD PRODUCTION T

• MIXING = 170°C

• COMPACTION = 160°C

WMALOW PRODUCTION T

• MIXING = 130°C


Which TEMPERATURE??







Materials

Testing

Results & Analysis

Work in Progress

Conclusions

OUTLINE





Cyclic triaxialcompression test

[UNI EN 12697-25]

Effects related to

RAP % + WMA

Stiffness

Ru

ttin

gT

he

rma

l cra

ckin

g

Fatigue

Cyclic uniaxialcompression test

[AASHTO TP 79-09]

Repeated Load Indirect Tensile Test[BS DD ABF]

ITSM[EN 12697-25]

Semi Circular Bending test

[UNI EN 12697-44]

Compactability and volumetric properties

Self-healing

ITS[EN 12697-23]

Adhesion - BBS[AASHTO TP 91]

BINDER

Testing





Cantabro test[UNI EN 12697-17]

Strength Crack initation

Indirect Tensile test[UNI EN 12697-23]

WetDry

Semi Circular Bending test

[UNI EN 12697-44]

Cra

ck p

rop

ag

atio

nS

tab

ilityCompactability

WetDry

Submerged

WetDry

Marshall[UNI EN 12697-34]


POROUS ASPHALT

Testing

Effects related to

RAP % + WMA

Repeated Indirect Tensile test





Cantabro test[UNI EN 12697-17]


Crack initation

Adhesion


POROUS ASPHALT

Testing

Effects related to

RAP % + WMA







Materials

Testing

Results & Analysis

Work in Progress

Conclusions

OUTLINE





Results & Analysis

=≠

…

Compactability

Overall performance compared to standard requirements

Most suitable WMA technology

Water susceptibility

WMA additive dosage

....





0

300

600

900

CRS CRW CWC CWO CWZ

Co

mp

acti

on

En

erg

y I

nd

ex

[-]

D = 150 mmGyrations: 120

Gyrations 8th gyration

% G

mm

Final bulk density

Compaction Energy Index

(CEI)

Final gyration

Compaction Energy Index (CEI)

B_H B_W B_WC B_WO B_WZ





Results & Analysis

EFFECTS OF WMA ADDITIVES:

fulfillment of technical standard limits for the Italian motorway system

Good overall performance compared to standard requirements

=





4,0% 5,2% 4,4% 4,8% 4,7%0

1

2

3

4

5

6

7

CRS CRW CWC CWO CWZ

Vo

ids [

%]

D = 150mmGyrations: 120

Air voids

Technical specifications






Indirect Tensile Strength (ITS)

V = 3.8% V = 6.3% V = 4.0% V = 4.1% V = 3.6%0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

2,0

CRS CRW CWC CWO CWZ

Ind

irect

Ten

sil

e S

tren

gth

IT

S [

MP

a]

T = 25°CD = 100 mm







0,00

0,10

0,20

0,30

0,40

0,50

0,60

0,70

0,80

PA_H PA_W PA_WC PA_WO PA_WZ

Ind

irect

Ten

sil

e S

tren

gth

IT

S [

MP

a]

T=25°CDRY







equal or improved gap

Performance compared to HMA:

regardless of the additive type

Results & Analysis

DOSAGE OF WMA ADDITIVES

≠





Results & Analysis

DOSAGE OF WMA ADDITIVES

≠

ADDITIVE AMOUNT = % by VIRGIN bitumen weight

BUT…





Results & Analysis

Different amount of virgin bitumen due to different amount of RAP

≠25% RAP 15% RAP

=> different amount of additives (HIGHER FOR PA)

PA mixtures: too soft





Results & Analysis


≠25% RAP 15% RAP

PA mixtures: MONOGRANULAR

less workability required than binder mixtures

less softening effects(less WMA %)

PA mixtures could even required less WMA %





Results & Analysis


≠25% RAP 15% RAP

To obtain the same effect of WMA additives on mixture performancebetween binder and PA mixtures, the WMA dosage must be calculatedrespect to the WORKING BITUMEN (virgin bitumen + re-activated RAP)





Step 1 Step 3Step 2





0,00

0,10

0,20

0,30

0,40

0,50

0,60

0,70

0,80


Ind

irect

Ten

sil

e S

tren

gth

IT

S [

MP

a]

T=25°CDRY



WMA: PLANT PRODUCTION (lower % additive)





Results & Analysis

=

Best performance

compared to the other WM additives

CHEMICAL ADDITIVE





Semi-Circular Bending test (SCB)

0

5

10

15

20

25

30

35

0,0

0,5

1,0

1,5

2,0

2,5

3,0


Fra

ctu

reto

ug

hn

ess

[N/m

m1.5]

Fra

ctu

reE

nerg

y G

[kJ/m

2]

Fracture energy

Fracture toughness

T = 10°C






HMA

Low T (NO additive)Chemical additive

Organic additive

Zeolite

50

500

500 5000 50000 500000

ε[μ

str

ain

]

Nf

T = 20°C






HMA

Chemical additive

Organic additive

50

500

500 5000 50000 500000

ε[μ

str

ain

]

Nf

T = 20°C





Cyclic Triaxial Compression test

(Rutting)

0,0

0,1

0,2

0,3

1 2 3 4 5

f c[μ

str

ain

/10

2cycle

s]


T = 60°C





0

2

4

6

8

10

12

14

16

18

20

0,00

0,50

1,00

1,50

2,00

2,50

3,00


Fra

ctu

re T

ou

gh

ness K

[N

/mm

1,5]

Fra

ctu

re E

nerg

y G

[kJ/m

2]

Fracture Energy

Fracture toughness

Semi-Circular Bending test (SCB)

T = 10°C





0

10

20

30

40

50

60

70

80

90

100


Part

icle

lo

ss P

L [

%]

Particle loss (Cantabro)

International requirements high traffic motorways

DRY DRY

DRY

DRY DRY

T=25°C

Voids≈20%





0

10

20

30

40

50

60

70

80

90

100


Part

icle

lo

ss P

L [

%]

Particle loss (Cantabro)

International requirements high traffic motorways

DRY

WET

DRY

WET

DRY

WET

DRY DRY

WET WET

T=25°C

Voids≈20%





0

500

1000

1500

2000

2500

3000

3500

4000


Nu

mb

er

of

pu

lse a

t fa

ilu

re [

-]


T=10°C

> 80% > 80%≈ 30%

DRY

WET

DRY

WET

DRY

WET

DRY

DRY

WETWET







Materials

Testing

Results & Analysis

Work in Progress

Conclusions

OUTLINE





Step 1 Step 3Step 2





Which TEMPERATURE??

• MIXING = 130°C






Chemical additive

Which ADDITIVE??

Full scale trial sections

on an in-service Italian motorway

for both BINDER and POROUS ASPHALT





1. Plant modification and calibration for the WMA additive





2. First production and lay-down attempts :

TEMPERATURE CONTROL AND COMPACTABLITY EVALUATION

preliminary studies on warm recycled mixtures for …

Documents