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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