François Olard (EIFFAGE Travaux Publics) Vincent … Gaudefroy (IFSTTAR-LUNAM) 2nd International...

2nd International Warm Mix Conference, St. Louis, October 11–13, 2011

Laboratory assessment of mechanical performanceand fume emissions of LEA® HWMA (90°C)

vs. traditional HMA (160°C)

François Olard (EIFFAGE Travaux Publics)Vincent Gaudefroy (IFSTTAR-LUNAM)


• Research of lower mixing temperature to target comparable HMA mechanical properties (at least « sufficient » for requested properties)

– Ladis Csanyi, Iowa introduced steam in hot bitumen in order to mix cold aggregates

– August Jacobi, 1928 in Germany patent foamed bitumen– real industrial tests happened in the 70’s in Australia– in France Jean Lefebvre (nowadays EUROVIA) in the 70’s tried to

realize surface dressings with foamed bitumen

Half warm mix process


Processes used: HMA and HWMA

°C L Fuel/T

Warm MixAsphalts

Hot MixAsphalts

HEATING

VAPORIZATION

DRYINGHalf-Warm Mix Asphalts

20 40 60 80 100 120 140 160 180

7

6

5

4

3

2

1

0

Cold MixAsphalts

Manufacturing temperature of asphalt mix (°C)

HMA

LEA® mixturesHWMA


Objectives of the study

– Study the effect of manufacturing temperature (HWMA LEA® and HMA) on mechanical and environmental properties

– Identify the effect of process on emissions (Total Organic Compounds quantity and Emission Potential)


Laboratory HWMA LEA processes

PHASE 1Dry hot 1st fraction of

aggregatesLEA

1160°C

PHASE 2Hot bitumen incorporation

160°C

PHASE 3: Cold and moist 2nd fraction of aggregates

Possible extra water added

PHASE 4: Thermal equilibrum reached between aggregate, residual water and bitumen

95°C

LEA

2

LEA

3

+160°C15°C

PHASE 1: Dry hot 1st

fraction of aggregates and cold and moist 2nd fraction

95°C

PHASE 2Possible extra water added to get an optimized water content

PHASE 3 Hot bitumen incorporation

160°C

95°C 95°C

160°C95°C

PHASE 4: Thermal equilibrum reached between aggregate, residual water and bitumen

PHASE 1The entirety of

aggregates are warmed

150°C


Formula Classical French dense asphalt mixture for base course ‘Grave Bitume’ GB 0/14 with a binder content of 4.2%

Aggregates diorite

Bitumen (35/50 pen-grade) Paraffinic : Pen-grade 42, R&B 52.6°C

Manufacturing temperature HMA: 160°C HWMA (LEA 1, 2 and 3): 95°C with 1.5% humidity by weight of dry aggregate

Additives 2 additives (vegetal origin) used (0.5% by weight of binder)

Materials used


Workability (Nynas Maniabilimeter)

0

20

40

60

80

100

120

140

160

HMA LEA1+O LEA2+O LEA2+G LEA3+O

Forc

e (N

)

Tests on two samples (with the same volume) cured 2 hoursat 110°C for HMA and at 75°C for H-WMA

The lower the force necessary to remove the mix from the mould, then the greater the onsite workability


Workability (GSC)

Aptitude au compactage à la PCG

80

82

84

86

88

90

92

94

96

98

1 10 100 1000

Nombre de girations

Com

paci

té (%

)

ChaudLEA2LEA3

HMA

Number of gyrations

Den

sity

(%)

LEA® mixes (90°C) appear to be slightly less workable than HMA (160°C)


The additive G makes LEA® a bit more resistant to water

Stripping resistance

0,4

0,5

0,6

0,7

0,8

0,9

1

HMA LEA1+O LEA2+O LEA2+G LEA3+O

Strip

ping

resi

stan

ce (-

)

Spec:0.7


Complex modulus

6000

7000

8000

9000

10000

11000

12000

HMA LEA 1 LEA 2 + O LEA 2 + G LEA 3

Com

plex

Mod

ulus

@ 1

5°C

10H

zby

Fra

ncke

n m

odel

(MPa

)• 2-point bending test at 15°C - 10Hz

Differences observed may be explained by the test repeatability as well as less binder ageing due to a lower manufacturing temperature for HWMAs


Airborne emissions methodology

Field studies

Organic emissionsduring construction

generated byasphalt mix

Laboratory studies

Fumes generatedby bitumen

Laboratory studies

Fumes generatedby asphalt mix at

LCPC

[Brandt et Al., 2000]

[Brandt et Al., 2000]


TOC(e)

Volatile and semi-volatile organic compounds : VOC and SVOC

Organic aérosols

Gas

Bituminous mixture manufacturing (and implementation)

Fumes

Inorganic particles

Particles

Compounds emitted in our laboratory conditions

Composition of bituminous fumes


Mixer

TOC(E) probe

Hydrogen and Air bottles

Stack

Analyser

Oil bath

Bitumen

Steamed water

Temperature probe

Stirringdevice

TOC(E) sampling system

Functions- Generate fumes- Collect / Sample- Analyse

Parameters- Formula- Binder- Process- Additive

ObjectiveEnvironmental assessement of bituminous mixes and binders in lab

LCPC experimental method


Total organic compounds measurement sampling system

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 (up to 2 min at a stirring velocity of 20 rpm and then 28 min without stirring in loose mix configuration)

One studied indicator


Effect of production process on Emission Potential

Lower Emissions in the case of LEAs

Influence of processes on Emission Potential results (mixes)


Influence of manufacturing and parameters process upon TOC(e)

emissions


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)

Pen

etra

tion

(1/1

0mm

)

53

54

55

56

57

58

59

60

61

Rin

g an

d B

all T

empe

ratu

re (°

C)

LEA3LEA2 LEA1

HMA

Bitumen aging and fumes emissions

Correlation between Emission Potentiel and bitumen aging


• Main findings

– The values of stiffness modulus and fatigue resistance for the LEA mixes are very close to those obtained for HMA

– Use of experimental devices by IFSTTAR to assess environmental properties of asphalt mixes (Hot, Warm and Half-Warm mixes asphalt) and bitumen

– A lower manufacturing temperature leads to a global emission reduction in laboratory

– Mix composition and manufacturing conditions influence emissions

Conclusions

François Olard (EIFFAGE Travaux Publics) Vincent … Gaudefroy (IFSTTAR-LUNAM) 2nd International...

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