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Additives for

Warm Mix Asphalt


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Content :

Warm Mix Asphalt technologies

CecabaseRT technology

Advantages of CecabaseRT

Examples of field jobs


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Warm Mix Asphalt technologies


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4

To remove liquid waterin theaggregates

To reduce the bitumen viscosityenough to fully coat the aggregates in

a time scale compatible with theprocess

4

Working at high temperature isnot artificial, it is necessary:

0

1

2

3

4

110 120 130 140 150 160 170 180

Temperature (C)

P

en35/50BitumenViscosity(Pa.s

)

Why we use hotmixes?

T

AGGREGATE

1. The bitumen temperature is fixedby the refinery vacuum distillation processpractically, difficult reduce bitumen T.

2. The aggregates represent ~95% of an asphalt mixture.

Buthow to reduce the asphalt mixture fabrication temperature?

Decreasing the process temperaturetranslates into decreasing the aggregates

temperature.


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Water Foam based processes

Consists in adding waterto form a foamwhen the water evaporatesdue tothe mix temperature. The water may be added directly (nozzles) or indirectly usingzeolites, wet fine mineral aggregates, emulsion, etc..

Improves aggregates coating thanks to an apparent volume enhancementof binder bythe foam. Probably improves workability of the mix thanks to lubricating effect of the foam.

m m m m

Grampr, L, Gonzalez-Lon, J,A. and Barreto, G. (2008) Enrobs tides par additivation chimique Revue Gnrale des Routes, No866,2008, pp 44-50.

http://www.astecinc.com

Zeolite

Compaction can become an issue as thefoam disappearsshortly after production

These techniques usually require amodificationof the mixing plant

Precautions should be taken due to the

addition of water(cohesion of theasphalt mix, water susceptibility of the mix)
http://upload.wikimedia.org/wikipedia/commons/5/58/Zeolite-ZSM-5-3D-vdW.pnghttp://upload.wikimedia.org/wikipedia/commons/5/58/Zeolite-ZSM-5-3D-vdW.png


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Allows for a coverage of the mineral

aggregate at reduced temperatures

Below the crystallizationtemperatureof the wax (~100C)workability of the mixture becomespoor and compaction cant beachieved.

The addition of waxes change thebitumencharacteristics (Penetrationgrade, viscosity, low temperatureproperties, etc)

Wax based chemicals additives

Additives (used at 2-3 wt% in asphalt binder) that reduce the viscosity of the

asphalt binder at processing conditions

Improved aggregates coating at lower temperature thanks to viscosity reductionof binder by the liquid (melted) productwhich acts as a solvent. An improvedworkability of the mix is possible to the lower viscosity of binder

Hurley, G.C.; Prowell, B. D. Evaluation of SASOBIT for us in Warm mix asphalt.

NCAT Report 05-06. June 2005


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Surfactant additives

Addition of a chemical surfactantadditive (0.3-0.5 wt% in the binder) thatchanges interfacial propertiesof the binder without changing asphalt binderrheology

Improved coatingat lower temperature thanks to surface tension reduction at thebinder/aggregate interface

Improved workability of the mix thanks the control the interface structurebetweenbitumen and aggregates, thus reducing the internal frictionsthat increase theworkabilityof an asphalt mixture.

Improved striping resistance of the mix thanks to surfactant action at binder/aggregateinterface

Chemical additive


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9

SurfactantAdditives

Wax Additives

Foaming

techniques

Zeolites

TC reduction Cost per ton of mix Pros and Cons

- 40C ~ 1/T

Cheapest and easiest additive technique

Robust, compaction aid

Anti-stripping effectkeep HMA mechanical prop.

Effective for long hauling

Consumption of Additive for each ton produced

- 30 to - 40C 2 - 3/T

Increase rut resistanceEffective for long haulingComplex to incorporate (solid pellets)Compaction issues below crystallization ~100CModification of binder (low T properties, cracking)

- 15 to - 30C0 but several

10,000investment

Cheap Process after initial investmentShort lifetime of foam

Average aggregate coating at WMA temperatureMix sensitive (binder, aggregate, lime)

- 30C 2 - 3/T

Increased lifetime of the foamPlant modification, complex introduction kit

Anti-strip often necessaryModification of mix design

WMA techniques in a nutshell


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CecabaseRT technology


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Typical properties of the additive :

LiquidViscosity < 1000 cPo at 20C Density :~ 1.00

Flash point : > 200C

Readily soluble in asphalt binder

Packaging: bulk, ~1000kg IBC,~200kg drums (1 drum eq. to 1000T of mix)

How to use CecabaseRT :

In line orbatchaddition to the asphalt binder

0.3 to 0.5%dosage based on total binder weight

Compatiblewith all kinds of bindersno curing time

Stablein stored asphalt binder over 7 days

Mix production temperature is reduced to120-140C depending on mix type : Heating of aggregates is typically ~ 40C less than

the corresponding HMA

Binder temperature remains the same as HMA

Good compaction is ensured down to 90-110C

How to use CecabaseRT

Asphalt (usual T)

Aggregates

(reduced T)

WMA


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Effect of Cecabase RT on binderproperties

Dynamic viscositymeasured at constantshear rate : 100 s-1

0.1

1

10

100

80 100 120 140 160

Temperature (C)

Viscosity(Pas)

Neat 35/50 bitumen

+ 0.3% additive

+ 0.5% additive

Since the additive interact at

the aggregate surfaceand

only small amountsare

required to have the improved

workability on the mix thereis no effect on the properties

on the binder

Viscosity unchanged bythe additive atconcentrations used


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Effects of CecabaseRT

50/70Asphalt

50/70 Asphalt+ 0.5% CB RT

30/45Asphalt

30/45 Asphalt+0.5% CB RT

SBS modifiedAsphalt

SBS modifiedAsphalt +0.5% RT

Penetration(1/10mm)

51 50 33 37 52 56

Ring andBall (C)

51.2 50.8 54.2 53.6 57.8 57.2

No change in Asphalt penetration grade or R&B temperature

Electron microscopy shows no difference of mix with HMA :

mm

25 m

Good distribution ofaggregates

Good coverage ofaggregates (even fines)


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Effect of additive on the mix

160C 120C

Reference mix Mix +0.5%Cecabase RT

Reference mix Mix +0.5%Cecabase RT

Void % 2.0 1.9 3.2 2.8

Marshall Stability

(kN)

11.0 10.5 8.8 10.0

Usually only small differencesare observed through standard compactionmethods (ex. Marshall)

The effect of the additive is seen on the workabilityof the asphalt mix.

However, the evaluationof workability in the laboratory can be quitechallenging

Bennert, T.; Reinke, G.; Mogawer, W.; Mooney, K. (2010) Assessment of Workability / Compactability of Warm Mix Asphalt.

2010 TRB Meeting Proceedings, paper 10-2223


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Workability effect of Cecabase RT

Evaluation of the workability of WMA in the lab is challenging

Test based on the recommendations onreport 691 from NCHRP (US)

Comparison of the number of gyrationsrequired to achieve a given void % with agyratory compactor :

Evaluation by laboratory BaustofflaborHamburg, following standard German testfor workability

Torque recording of a screw type rotationaldevice introduced in the mix :

Mixing at 120C, measurement at 90C, 8% void240

250

260

270

280

290

300

310

320

330

Reference asphalt mix Asphalt mix with 0,5%

Cecabase RT

Reference asphalt mix Asphalt mix with 0,5%

Cecabase RT

160C 120C

Torque(N.cm)

0

50

100

150

200

250

300

Control HMA 160C Control WMA (no add it ive) 120C WMA 120C - Cecabase RT - 0 ,4%

Gyration#


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Improvements of adhesion are achieved with CecabaseRT

ITSR :

Mechanical characterization

Open-graded friction course with modified binder, PG 76-28Compaction PCG 600kPa, 40 gyrations

Conditioning 1 day in water at 60C0

2

4

6

8

10

12

14

Void % ITS (kN)

conditioned

ITS (kN)

Void%

orITS(kN)

Reference HMA 160C

Reference WMA 120C without additive

WMA 120C with 0,4% Cecabase RT

TSR

Hot Mix Asphalt 0.58

WMA without

Additive 0.31

WMA with

Cecabase RT 0.84


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Hamburg Test

The hamburg test is a mix between a rutting test and a anti-stripping test.

Gmm (Maxtheoretical

specific gravity)

Air voids (%) Max. rut depth(mm)

HMA (160C) 2.425 6.95 -13.3

WMA (130C,

0.4% CB RT)2.445 7.2 -9.1

AASHTO T324

0/25mm mix, compacted in SGC

20,000 wheel passes

In water at 50C

http://www.fhwa.dot.gov/pavement/asphalt/labs/mixtures/hamburg.cfm

Hajj, E.; Cortez, E. Evaluation of the Cecabase RT warm mix additive, final report. Septembre 2001 University of

Nevada, Reno US


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Rutting resistance

NF P 98-253-1 Hot mixasphalt

Warmmix

asphalt

Limits inthe std.

Rutting (%)after 30,000cycles

4.11 4.19


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Fatigue

Oliveira, J.; Silva, H.; Abreu, L.; Gonzalez-Leon, J. The role of a surfactant based additive on the production of

recycled warm mix asphaltsLess is more. Construction and Building Materials 35 2012 693-700

Evaluated by the University of Minho (Portugal) on a regular 0/10 mix and a 0/10 mix with50% RAP, following the EN 12697-24.

4 point bending test

T 20C, 10 Hz

Mix A 0/10

Mix B 0/10 + 50% RAP

Similar Fatiguebehaviorbetween HMAand WMA with

additive


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Advantages of CecabaseRT


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2121

Compaction aid

Fast opening to traffic

Less heat & fumes

Environment Comfort Flexibility

Advantages of WMA with CecabaseRT

Less emissions

Energy savings

Increase use of RAP

Increased capacity

Night or winter work

Longer hauling


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Reduction of gas emissions

CO2

(Nm3/ton)

Eq. NO2

(g/ton)

TVOC

(g/ton)

PAH

(g/ton)

HMA 14.6 6.8 80.6 78.6

WMA 9.0 5.0 14.3 35.5

-38% -26% -83% -55%

Measurements taken on job site, on a worker, a paver driver anda compactor driver :

Typical values measured at the plantstack (production of very thinasphalt cement) :

Worker Paver Compactor

HMA 0.01549 0.0097 *

WMA 0.0053 0.0045 0.0019

-66% -54% *

Both HMA and WMA are well below exposure limits

(close to detection limits)

More than 20 different polyaromatics (PAH)

measuredexample :

Naphthalene(mg/m3)


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Increased use of recycled material

120

160

200

240

280

320

360

400

440

480

0 10 20 30 40 50

% RAP

AggregateT(C)

Tmix 120C

Tmix 160C

Calculated temperatures

+ 10-15% RAP

RAP

Virgin aggregates

CecabaseRT increase the amount

of RAP that can be introduced inthe mix by 10 - 15% :

Easier mix compaction

Less overheating of virginaggregates

Working for plants with and withoutheating systems for RAP

Significant reductions of the asphaltmix cost

Also possible with shingles (RAS)and crumb rubber (CRA)

Cold RAP

systems

Pre-heated

RAP systems


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Use as Compaction Aid

The workability effectof CecabaseRT can be used

to achieve the desired compaction target at Hot Mixtemperatures in various cases :

Fasterprogression : typically fewer compaction passesare required compared to HMA without additive

Gives more securityfor difficult mixes (high-end void%)

Increase chance of getting compaction bonus

Improve workability of stiff mixes(high RAP ) Ability to work at


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Dust

(mg/m3)

Fumes

(mg/m3)

Mix ofPollutants

(mg/m3)

HMA 12 11.4 12

WMA 3.5 3 2.9

-71% -74% -76%

Similar reductions are measuredat the plant:

Reduction of dust and fumes

Typical reductions measured on the paver(SMA job) :

HMA WMA


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Increase of Production rate

In some cases, residence time of aggregates in the barrel can bedecreased (lower heating T) without changing the burner settings

Case study : an increase from 210 to 280 tons of mix/hr (~ 30%

increase) was possible when switching from HMA to WMA

Useful during peak seasonor for debottlenecking

Flexible technology : easy to switch from HMA to WMA and back

Asphalt (usual T)

Aggregates

WMA120C


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Longer hauling

80

90

100

110

120

130

140

150

160

170

0 50 100 150 200Time (min)

Tem

perature(C)

WMA HMA

Limitfor WMA paving

HMA production

WMA production

+ 200%+25%

Limitfor HMA paving

A WMA with CecabaseRTmay be paved up to 25% later than standard HMA

A HMA with CecabaseRTmay be paved after a hauling time up to 3 timeslonger

t0


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Examples of field jobs


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Examples of field jobs - France

Bordeaux 2008High traffic road

High modulus asphalt cement (EME)

10/20 [1/10mm] asphalt

Produced at 130C (normally 170C). Laid down at 125C

Average density 95,6%

Gaillac 2011BBSGStandard 0/10 mm wearing course (BBSG), 6 cm layer

0,4% Cecabase RT Bio10

Cecabase RT945 used at 0.4%, added in tank 5 days before

500 tons paved at 120CHigh volume road : AADT > 15000

St Flour 2009Highway A75

Open graded friction course (BBTM) Thin layer 2,5 cm

5,6% binder, polymer modified Styrelf 13-600,4% Cecabase RT945

4000 tons produced at 135C, paved at 120C, compacted at 110C


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Examples of field jobs - Europe

Poland 2007Stone Mastic Asphalt (SMA)

0-8 mm aggregates - 0.4% fibers in the mix

Asphalt binder Pen. 50 + 3% SBS0,4% CecabaseRT945

3000 tons produced at 130C, paved at 120C, compacted at 100C

Italy (Padova) 2012

Fine gradation D8 type15% RAP added cold at the plant

Asphalt 70/100 penetration0,4% CecabaseRT Bio10

Mix produced at 150C, paved at 130C, compacted at


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Examples of field jobs - AmericaNew York State 20082 different jobs

1300T dense-graded mix with 30% RAP (Road 31 along Seneca River)

1000T dense-graded mix without RAP (Road 18 near Utica)Production at 120-130C, paved at 120C with good workability

Tennessee (Sevierville) 2012

Mix with difficult limestone aggregate15% RAPhigh traffic road

Asphalt PG64-22CecabaseRT945 and antistrip

Night work, light rain - Mix produced at 130C, compacted at 113C

Canada (Alberta) 200925,000 tons job

Dense graded mix without RAP (gravel pit aggregates)Interstate 35

Asphalt binder 200-300 Pen. with antistrip + 0.2% CecabaseRT945

Produced at 120C (vs 150C for control HMA)

California 2010Caltrans project with crumb rubber

12.5mm gap graded mixAsphalt PG 64-16 with 18% scrap tire

0.4% CecabaseRT - Produced at 130C (vs 165C for control HMA)

Tested on Heavy Vehicle Simulator (HVS) Cecabase RT WMA ismore rut resistant than control HMA


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Examples of field jobs Asia & LatAm

Australia 2008High %RAP mix

Base and Wearing Courses Type H-10mm30 and 40% RAPrespectively

Paving temperatures : 108-115C

Average compaction around 95%

Japan 2009Open graded type

-30C to -50C temperature decrease - Rainy conditions3000 tons produced at 130C, paved at 120C, compacted at 100C

China 20110-8 mm aggregates - 0.4% fibers in the mix

Asphalt binder Pen. 50 + 3% SBS0,4% Cecabase RT

3000 tons produced at 130C, paved at 120C,compacted at 100C

Argentina 2010

Open graded type mixAsphalt grade CA-30 (pen 50/60) with0,4% Cecabase RT945

Temperature decreased to 130CCore sampling

l l b l


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A real global coverage

Today Cecabase RT is present in more than 50 countries

More than 150 different customershave chosen Cecabase RT additives

Several millions tonsof Warm Mix Asphalt are produced each year withCecabase RT technology

Field jobs

Lab trials


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A simple way to reduce temperature of asphalt mixes by~ 40C by the addition of a liquid additive :

Patentedtechnology used since 2004on the field

Robust, work with all binders and asphalt mixes

No plant modification or high maintenance costs

Most cost-competitivesolution among additives

Systematic back-upof CECA technical experts

Mechanical properties of WMA are similar to thoseobtained with a control HMA

Benefit from immediate advantages :

Environment: reduction of emissions, gas savings,use of RAP

Comfort: compaction aid, less heat & fumes, quickopening to traffic

Flexibility: increased plant capacity, longer hauling,night or off-season work


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Th k !

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