ASPHALT PAVEMENTS DEGRADE INTERNATIONAL WORKSHOP ASPHALT RECYCLING AND MATERIALS RE-USE IN ASPHALT PAVEMENTS Prof. Sandro Colagrande – University of L’Aquila Società Italiana

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INTERNATIONAL WORKSHOPASPHALT RECYCLING AND MATERIALS RE-USE IN ASPHALT PAVEMENTS

Prof. Sandro Colagrande – University of L’Aquila Società Italiana Infrastrutture Viarie

INFLUENCE OF COMPACTION AND MATURATION TIME ON COLD-RECYCLED ASPHALT PAVEMENTS WITH

FOAMED BITUMEN AND CEMENT

Thursday 28 June 2007 – University of L’Aquila – Faculty of Engineering



ASPHALT PAVEMENTS DEGRADEREASONS

1) ENVIRONMENTAL FACTORS

• thermal excursions

• water presence

• solar action (UV ray)

• load entity

• number of passages

2) TRAFFIC LOAD

EFFECT

Ramified cracks Holes Deformations

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Operation Type

ROAD PAVEMENTS MAINTENANCE

p yp

Traditional Method RECYCLING

• Milling operation

P tti th ill d h lt•Putting the milled asphalt concrete into dump

• Hot mix asphalt spread out withvirgin aggregates taken from quarry



Operation Type


p yp


HOT RECYCLING COLD RECYCLINGHOT RECYCLING COLD RECYCLING

Heating milled asphalt(more energy and smoke emission)

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Operation Type


p yp


HOT RECYCLING COLD RECYCLINGHOT RECYCLING COLD RECYCLING

BituminousEmulsions

FOAMEDBITUMEN



FOAMED BITUMEN

Foaming process Expansion room

The foamed bitumen is obtained by a process carried out inside an

expansion room in which both the hot bitumen (170-180 °C) and a little

quantity of water (1-2 % of the bitumen weight) that is introduced at environmental temperature and at a

Hot Bitumen

ColdWater

ppressure of 10-12 bars, are sprinkled.

Such process produces a foamy product that expands remarkably up to 15-20 times in comparison to the

bitumen initial volume. Foamed Bitumen

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FOAMING PROCESS

The foam produced dissolves in less than one minute and the binder regains its initial properties. Therefore, the bitumen must

immediately be mixed to the aggregate.



RECYCLING WITH FOAMED BITUMEN

ROTOR OF MILLING-MIXING

Production

Binder (160 ÷ 180°C)

Water (3-4 % of the RAP weight)Foamed water

(1-2 % of the bitumen weight)

Speed of advancement: v = 8 ÷ 15 Km/ h

180 ÷ 300 m3/ h

direction of work

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RECYCLING WITH FOAMED BITUMENCATEGORIES OF COLD RECYCLING

Deep Recycling

(15 ÷ 25 cm)

Superficial Recycling (5 ÷ 10 cm)



RECYCLING WITH FOAMED BITUMENRECYCLING TRAIN

Recycling machine

Bitumen tanker

Water tanker

Roller machine Grader

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EXPERIMENTAL PHASES

• Works performed in site

• Laboratory survey

• Investigation on the specimens taken from the site



INDIRECT TENSILE TESTS

The instrument’s scheme

Tension state of the specimens

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160%

THE OPTIMAL MIXTURE

Good compromise between development of elevated Resistances and good values of Ductility

60%

80%

100%

120%

140%good values of Ductility

0%

20%

40%

Duttilità 49% 14% 0% 76% 50% 36% 100% 93% 61%

Resistenza 38% 85% 100% 55% 84% 87% 0% 46% 64%

C1-B2 C2-B2 C3-B2 C1-B3 C2-B3 C3-B3 C1-B4 C2-B4 C3-B4



INVESTIGATION ON THE SPECIMENS WITHDRAWN IN SITE

Objectivej

• To evaluate the influence of the compaction degree on the mechanical properties of the mixtures (4 and 8 passages of roller

compactor and Marshall compactor in laboratory);

• To evaluate the influence of the maturation time on the mechanical

• The purposes of this study are:

• To evaluate the influence of the maturation time on the mechanical performances of the mixtures (3, 7 and 28 days).

Way

• Indirect Tensile Tests

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INDIRECT TENSILE STRENGTH

Rt

0,20

0,30

0,40

0,50

0,60

0,70

0,80

Rt (

N/m

m2 )

0,00

0,10

Specimens

Rt (03days) 0,25 0,36 0,27 0,42 0,31 0,43

Rt (07days) 0,30 0,38 0,31 0,45 0,32 0,56

Rt (28days) 0,53 0,69 0,62 0,72 0,52 0,63

BM Site 4 SF Site 4 BM Site 8 SF Site 8 BM Site-Lab SF Site-Lab



TIME INFLUENCE ON THE INDIRECT TENSILE STRENGTH

Rt - TEMPO

0,8

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

Rt (

N/m

m2 )

0,00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Time (days)

SF Site 4 SF Site 8 SF Site-Lab SF Site 4 SF Site 8 SF Site-Lab

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MATURATION VELOCITY OF THE MIXTURES

VELOCITA’ DI MATURAZIONE

0,004

0,006

0,008

0,010

0,012

0,014

0,016

d(R

t)/d

t

0,000

0,002

,

WorksBASE - MODIFICA 0,0112 0,0122 0,0084

SUPERFOAM 0,0138 0,0123 0,0062

Site 4 Site 8 Site-Lab



CONCLUSIONS

CONCLUSIONI

The mixtures compacted with lower energy (4 roller passages) are f t d b t ti l it hi h th th t f i tfeatured by a maturation velocity higher than that of mixtures

compacted with higher energy (8 roller passages).

Is this a good thing? What are their fatigue behaviors?

THESE ARE MY QUESTIONS

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Thank you for the attention

Documents

ASPHALT PAVEMENTS DEGRADE INTERNATIONAL WORKSHOP ASPHALT RECYCLING AND MATERIALS RE-USE IN ASPHALT PAVEMENTS Prof. Sandro Colagrande – University of L’Aquila Società Italiana