Overview of French Research ProjectOverview of French Research Projecton Cold Mix Asphalt Recyclingon Cold Mix Asphalt Recycling

for Road Construction / Maintenancefor Road Construction / Maintenance

Vincent GAUDEFROYVincent GAUDEFROY

June 4, 2012June 4, 2012

IFSTTAR – June 4, 2012

Time-dependent behaviour Strong behaviour changes during its life from unbound

material to HMA behaviour : curing and cohesion build-up

Local competences Mix design and manufacture are empirical Many difficulties to ‘spread’ CMA processes

over French territory

Research program - Assess pavement layer behaviour versus

time - Develop mix design methodology

Cold mix asphalt propertiesCold mix asphalt properties

IFSTTAR – June 4, 2012

Assess pavement layer behaviour versus time

Construction and monitoring of experimental sections Departmental Road n°20, October 2006 (with local authority CG31) Departmental Road n°44, July 2008 (with local authority CG35 and

French Union of Road contractors USIRF)

ExperimentationExperimentation

IFSTTAR – June 4, 2012

Instrumentation installation on RD44 worksite

RD44 experimentation

a single testing zone (12.3 m long) has been instrumented by placing probes and sensors in the new GE (12 cm thick) layer

Compaction step on testing zone

• GE layer in the probes and gauges zone was not submitted to vibrating compaction to preserve probes

• To obtain required in situ voids content, the pneumatic-tyred roller passes number has been increased (32 passes).

IFSTTAR – June 4, 2012

CMA internal behaviour Gauge responses Temperature and moisture evolution

Strain gauge and optical fibres

Optical fibres

TDR probe (moisture)

Internal instrumentation (CMA Layer)

IFSTTAR – June 4, 2012

Climatic conditions (rainfalls, wind, solar UV, atmospheric IR radiations)

Objective

Globally assess local weather features and correlate them with in situ curing of the GE

External instrumentation (climatic conditions)

IFSTTAR – June 4, 2012

CMA internal behaviour Cored and sieved samples to check binder characteristics and

mixes mechanical performances (EN 12697-26) over time

Additional assessment

Two-point bending complex modulus test, uniaxial direct tensile test, indirect tensile stiffness test (diametral pulse loads)

IFSTTAR – June 4, 2012

Methodology usedMethodology used

Constituents and worksite control Aggregate and grave-emulsion characteristics On site workability (French gyratory compactor PCG2) Jobsite mix cohesion characterization (workability test and

torque measurement)

0

5

10

15

20

25

30

1 10 100 1000Gyration number (-)

Voi

d c

onte

nt

(%)

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40

0,45

0,50

Nor

mal

ised

wat

er e

xru

ded

(-)

Void filled by water

Void filled by air

Water extruded

Total void

A French Experimental Worksite to Assess in situ Cold Bituminous Mixtures Behaviour, Wendling et al. ISAP NAGOYA, 2010

Gyratory Compactor workability of RD44 CMA

French gyratory compactor PCG2

IFSTTAR – June 4, 2012

Global pavement behaviour (external auscultation techniques: Deflexion (Deflectograph Flash, Falling Weight Deflectometer), permanent deformations and transverse profile (PALAS) in continuous mode)

Falling weight deflectometer FWD

PALAS (laser profilemeter)

French Deflectograph FLASH

Methodology usedMethodology used

IFSTTAR – June 4, 2012

Deflexions decrease with time

Maximum deflexion measured by FWDMaximum deflexion measured by FWD

0

200

400

600

800

1000

1200

1 m

onth

bef

ore

Implem

enta

tion

3 m

onth

s afte

r

10 m

onth

s afte

r

15 m

onth

s afte

r

22 m

onth

s afte

r

Max

imu

m d

efle

xio

n (

µm

)1st

summer1st

winter2nd

summer2nd

winter

(Jun

e 20

08)

(July

200

8)

(Oct

2008

)

(May

200

9)

(Oct

2009

)

(May

201

0)

IFSTTAR – June 4, 2012

Research subjects on CMAResearch subjects on CMA

Monitoring jobsite behaviour Classical in situ behaviour assessment (coring, mechanical

perf.) Links with binder ageing (extraction methodology,…) External auscultations and in situ instrumentation

Laboratory characterization methodology Correlate materials time-dependent behaviour with climatic

conditions Develop lab methodology (especially curing conditions) to

achieve CMA characterization

This study is in progress since 2007 (internal works at IFSTTAR and collaborative project with Private Industry)

IFSTTAR – June 4, 2012

CONCLUSIONSCONCLUSIONS

Great interest of Road Companies and French Administration for these environmentally friendly techniques with regard to sustainable development

Researches to check cold asphalt mixes properties Very short term : Equivalent to unbound materials Short term : bound materials (GSC, Modulus, Rutting, …) Long term : Properties durability (Fatigue)

Develop a collaborative mix and pavement design methodology (including specific tests – and experimental conditions evaluation dedicated to CMA assessment)

Standardization (French and European levels) of cold mixes

IFSTTAR – June 4, 2012

OutputsOutputs

4 MLPC methods as helping tools to design CMA treated with bitumen emulsion (2011 - in French)

MLPC 74 : Coating quality and consistency MLPC 75 : Hydrous stability of CMA (manufacturing, transport, storage) MLPC 76 : Cohesion evolution (workability, torque measurement) MLPC 77 : Aggregate reactivity of emulsion/aggregate couple

IFSTTAR – June 4, 2012

Collaborative project with the French Union of Road contractors

14 communications in a French journal « RGRA » (2011 to 12) → from manufacturing process in lab to CMA mechanical properties

Special issue available for the next congress Eurasphalt and Eurobitume (June 2012 - in English)

IDRRIM French working group Guide in progress on « Materials treated by emulsified bitumen and

foamed bitumen »

OutputsOutputs

IFSTTAR – June 4, 2012

Thank you for your attention !

contact :vincent.gaudefroy@ifsttar.fr