france’s perspective on warm mix: research and practice vincent gaudefroy ifsttar - france
TRANSCRIPT
France’s Perspective on Warm Mix: Research and Practice
Vincent Gaudefroy
IFSTTAR - France
2 IFSTTAR – June 4, 2012
Definition of Warm Asphalt Mixes
• Any practical/technical mean
• To allow reduction of manufacturing and/or laying temperature
• While keeping the same performances as Hot Mix Asphalt
• With final performances achieved just after laying and cooling
3 IFSTTAR – June 4, 2012
0 20 40 60 80 100 120 140 160 180
7
6
5
4
3
2
1
0
Cold asphalt
(°C)
L Fuel /Ton
Warm asphalt
Hot mix
asphalt
HEATING
VAPORIZATION
DRYINGHalf-warm asphalt
Terminology
Current practice of Warm asphalt in France
5 IFSTTAR – June 4, 2012
Development of WAM in France
• First studies and researches : 2000-2003
• Experimentation : 2002-2005
• Industrialization : since 2004-2006• Applications in various conditions
• Any type of network, traffic, climate
• Any type of material (surface or base course)
• New construction and maintenance
6 IFSTTAR – June 4, 2012
Types of processes used in France
• Use of binder additives to modify binder/aggregate interface and ensure coating at low temperature
• Use of bitumen foaming (pressure or not)• By keeping residual water in the aggregates
• By using water in aqueous phase ,…
• Use of sequential coating steps
7 IFSTTAR – June 4, 2012
Available products in France (2011)
Technique NameManufacturing temperature reduction (ºC)
Company
Binder Additive
ETIMA3E - LTEVOTHERM MA3EBT 130ºC
30 to 4530 to 4530 to 4530 to 45
MALETCOLAS GroupEUROVIAEIFFAGE Travaux Publics
Foaming process EVOTHERM DAT5EBT 130ºC
40 to 6030 to 45
EUROVIAEIFFAGE Travaux Publics
Foaming process and sequential coating
EBT 90ºCEBEEBT 130ºCWAM-FOAM3E - DB
50 to 8050 to 8030 to 45Up to 6040 to 45
EIFFAGE Travaux PublicsOperating licence (owner LEA-CO)EIFFAGE Travaux PublicsOperating licence (owner SHELL)COLAS Group
In addition : Increase of foaming processes (from US – Astek, Gencor, Maxam ….) Development of specific binder by French bitumen company (Total)
8 IFSTTAR – June 4, 2012
Consequences for asphalt plants
• No modification for specific binders or additives in bitumen
• Necessary modifications (more or less important) for
• Foaming
• Double coating
• Sometimes necessary reduction of production rate
9 IFSTTAR – June 4, 2012
Approximately near HALF million ton applied in 2008, 2010 : ONE million ton in France among 40 millions tons/year of HMA
Examples of quantitative evolution
0200400600800
100012001400160018002000
2008 2009 2010
BB tièdes
Source IDRRIM – May 2011
10 IFSTTAR – June 4, 2012
• In laboratory• Mechanical performances are similar as HMA• But stripping resistance (Duriez test) is slightly lower than HMA
• Manufacturing in plant• Production temperature from 90°C to 130°C• Residual moisture control seems difficult (for ‘water’ processes)
• Implementation and laying• Laying and compaction temperature from 70°C to 120°C• High compaction energy is required especially for base course• Workability at middle term must be monitored
• Environmental field • Reduction of emissions• Reduction of energy consumption
First assessment of French survey of WAM
Current research activities on WAM
12 IFSTTAR – June 4, 2012
Research needs
• Assess global energy consumption vs. traditional HMA
• Assess fume emissions reduction (effect of additives/binder)
• Assess coating quality in lab
• Assess durability under traffic
• Assess aging properties
• Assess usability of performance-based specifications (representativeness of laboratory manufacturing process vs. plant process)
13 IFSTTAR – June 4, 2012
LCPC Research project ‘OPTIMIRR’ 2006 -2012
• WAM = Environmentally friendly processes ?
- Aggregates (partly or fully) heated - Bitumen temperature still high
- Complexity of Mixing processes- Additives (paraffin, zeolites, …), recyclibility?
• Foaming bitumen with steamed water: ‘stripping effect’ = ecologic benefit ?
• Residual water content in warm mix : aggregate/bitumen interface durability, long term behaviour under heavy traffic ?
Lot’s of questions waiting for answers>> Researches in progress
Optimization of Pavement Materials and Reclaimed Asphalt Pavement Incorporated
into Roads
14 IFSTTAR – June 4, 2012
TOC(e)
Volatile and semi-volatile organic compounds : VOC and SVOC
Organic aérosols
Gas
Asphalt manufacturing (and implementation)
Fumes
Inorganic particles
Particles
Compounds emitted in our laboratory conditions
Asphalt fumes
15 IFSTTAR – June 4, 2012
Mixer
Stack TOC(e) probe
FID Analyser
Hydrogen and Air bottles
Functions- Generate fumes- Collect / Sample- Analyse
Parameters studied
- Mix design- Binder- Process- Manufacturing temperature
ObjectiveEnvironmental Assessment and ranking of bituminous mixes in lab Efficient laboratory tool to study and forecast asphalt fumes
LCPC Asphalt fumes generator
16 IFSTTAR – June 4, 2012
Time (s)
Emission Potential(mg.s/m3/kg of bitumen)
TOC(e) (mg/m3/kg of bitumen)
Evaluation and separation of TOC by a Flame Ionization Detector (FID)
Evolution of Total Organic Compounds TOC(e) emissions according to time at a stirring velocity of 20 rpm
One studied indicator = Emission Potential
Analytical systems to measure asphalt emissions
The emission Potential (EP) is calculated by integrating the area under TOC(E) curve according to time
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0
100
200
300
400
500
600
700
800
140°C 190°CTemperature °C
EP
* 1
03(m
g/m
3/k
g o
f b
itu
me
n.s
)BBSG GBBase HMAThick surface
HMA
0
100
200
300
400
500
600
700
800
140°C 190°CTemperature °C
EP
* 1
03(m
g/m
3/k
g o
f b
itu
me
n.s
)BBSG GBBase HMAThick surface
HMA
Increase of Temperature = Increase of TOC(e) emission
Temperature and mix design influence
Ref Gaudefroy ISAP 2008 paper 110
Binder content 3.75 % 5.1 %
WMA HMA
18 IFSTTAR – June 4, 2012
24
26
28
30
32
34
36
38
50 100 150 200 250 300 350 400
Emission Potential (103.mg.s/m3/kg of bitumen)
Pe
ne
tra
tion
(1
/10
mm
)
53
54
55
56
57
58
59
60
61
Rin
g a
nd
Ba
ll T
em
pe
ratu
re (
°C)
LEA3
LEA2 LEA1
HMA
Fresh bitumen: pen-grade 42 and R&B : 52,6°C Stirring time: 30 min
Bitumen aging and fumes emissions
Correlation between Emission Potentiel and bitumen aging
Ref Gaudefroy ISAP 2008 paper 103
H-WMAsH-WMA
19 IFSTTAR – June 4, 2012
Durability and performances of WMA
• Survey of existing job sites• French expert task group on ‘WMA processes’ of SETRA (road
directorate)
• Accelerated Pavement testing to assess durability under traffic
• Enabling to check performance based specification applicability for WMA
LCPC Test track
20 IFSTTAR – June 4, 2012
Conclusions
• WMA durable trend in France
• Increasing use with promising results
• Still research needs
• Need of a global environmental assessment tool (like for other techniques)
• Existing experiments on site for fume assessment to correlate to laboratory
• Need for job sites surveys
– To assess durability under traffic
– To check and/or improve performance based specifications for these mixes
