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Regenerators for HMA

The asphalt content of most old pavements (RAP) will

comprise approximately 3 to 6 percent by weight and 10 to

20 percent by volume of the pavement. Due to oxidation

aging, the asphalt cement has hardened and

consequently is more viscous and has lower

penetration values than the virgin asphalt cement.

Depending on the amount of time the original pavement had

been in service, recovered RAP binder may have

penetration values from 10 to 30 and absolute viscosity

values at 60 C as high 50,000 poises.

BITUMEN AGING: The main mechanisms for the aging of bitumen is oxidation

and the loss of volatiles. When bitumen ages it becomes higher in viscosity

(stiffer) and the composition changes noticeably. These changes can lead to

brittleness and loss of adhesion, especially in the presence of water, where

surface cracking and ravelling may occur.

OXIDATION: As bitumens age they incorporate oxygen at reactive sites. This

increases the polarity of the components, allowing the formation of molecular

associations that stiffen the binder.

VOLATILITY:Lower molecular weight oils fractions- part of they dispersing phase

may be lost by evaporation. This mostly occurs in handling but, depending on the

bitumen, occur over time in the surface of the road

REGENERATION OF AGED BINDER

Regeneration in principle is simple, replace the oils lost and rebalance the bitumen

composition so it is no longer brittle. This involves the use of a bituminous oils/resin

fractions. In general, alkylamide polyamine and aromatic to react with the free

radical and evaporated fractions.


Time Penetration Ring & Ball Penetration Ring & Ball

(months) dmm °C dmm °C

0 51 53 48 54

Lay 40 54.5 33 59.5

7 30 57.5 24 61.5

18 23 60 19 65.5

31 23 60 21 66

43 20 62.5 21 66.5

56 16 66.5 17 72

70 20 67 15 74

84 17.2 68.5 13.7 75.5

BITUMEN "B"BITUMEN "A"

51

40

30

23 2320

1620

17.2

53 54.557.5

60 6062.5

66.5 67 68.5

48

33

2419 21 21

17 15 13.7

54

59.5 61.565.5 66 66.5

72 74 75.5

0

10

20

30

40

50

60

70

80

0 Laying 7 18 31 43 56 70 84

Bitumen % change in PROPERTIES

VOLATILES: Bitumen % change in COMPOSITIONTime Asphaltenes Resins Aromatics Saturates

(Months) (% by Weight) (% by Weight) (% by Weight) (% by Weight)

0 13.7 19.3 63.0 4.0

Laying 18.4 27.6 49.7 4.3

18 20.4 27.8 47.0 4.8

56 21.2 27.9 46.4 4.5

84 23.4 28.0 44.2 4.4

13.7

19.3

63.0

4.0

18.4

27.6

49.7

4.3

20.4

27.8

47.0

4.8

21.2

27.9

46.4

4.5

23.4

28.0

44.2

4.4

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

Asphaltenes Resins Aromatics Saturates

Thermal and fatigue cracking: Regenerators for HMA

-10

-8

-6

-4

-2

0

2

4

Aged Bitumen 25% RAP 20% RAP 15% RAP Neat bitumen

Graph. 1: Thermal Cracking LmT

2,65 °C

-0,77°C

-2,39°C

-3,90°C

-6,72°C

0

5

10

15

20

25

30

35

40

45

50

Aged Bitumen 25% RAP 20% RAP 15% RAP Neat bitumen

Graph. 2: Fatigue cracking LmT

49,07 °C

27,05 °C24,34 °C 22,45 °C

17,86 °C

Thermal and fatigue cracking are two of the most frequent and evident problems in HMA

produced with RAP without introducing any additive to improve the rheology profile of the aged

bitumen.

A Performance Grade analysis on "fresh", aged bitumen and mixtures thereof, demonstrated the

higher thermal susceptibility of the asphalts that contain oxidised bitumen (graph 1 and 2).

The Need for Regenerators for HMA

If specifications are met at the lowest level (including production, laying and compaction

requirements), asphalt mixtures with specific functional properties (fatigue, durability,

stiffness, resistance against deformation and cracking etc) are produced. These properties

are used in design models to calculate the thickness of road required to fulfil its bearing

capacity for anticipated traffic volumes during a desired lifetime, surface characteristics

sufficient to generate a comfortable and safe journey.

ITERLENE ACF1000

REGENERATOR FOR BITUMENS

ITERLENE ACF 1000 is a multi-purpose additive which allows

the correct use of RAP (reclaimed asphalt pavement) in Hot

Mixes by regenerating the oxidized (aged) bitumen

ITERLENE ACF 1000 is made up of several chemical

compounds, each compound acts specifically on the bitumen as

it is, and on bitumen that derives from refineries, either aged or

oxidised, and from milled bituminous paving.

ITERLENE ACF 1000 is an anti-stripping agent, antioxidizer,

regenerating, plasticiser, and it also wets, disperses and dilutes.

ITERLENE ACF 1000 is pumped directly inside the bitumen

tank.

DOSAGE: ITERLENE ACF 1000 dosage can vary from 0.3% to

0.5% every 10% RAP of the NEW bitumen weight .

Rejuvenators for HMA

The mix composition is calculated by the asphalt producer, using the

raw materials data outlined above, the principal theme of this mix

composition being formed by the properties of RA, in particular the

properties and amount of the binder (= bitumen).

The philosophy is that the mixture of old and new bitumen should

meet the specification requirements of the bitumen normally specified

for a particular mix.

This implies properties in addition to the basic properties of Pen, TR&B

or viscosity.


Calculation of the Penetration of the binder of a mixture

a log pen1 + b log pen2 = log penmix

penmix: calculated penetration of the binder in the mixture containing reclaimed asphalt

Example:

pen1 = 20; pen2 = 90; a = 0,25 and b = 0,75 0,25 log 20 + 0,75 log 90 = log penmix log penmix =

1,79094; penmix = 62

Calculation of the Softening Point of the binder of a mixture

TR&B mix = a x TR&B1 + b x TR&B2

TR&B mix : calculated softening point of the binder in the mixture containing reclaimed asphalt

Example :

TR&B1 = 62 º C; TR&B2 = 48º C; a = 0,25 and b = 0,75 TR&Bmix = 0,25 x 62 + 0,75 x 48 = 51,5 º C

Calculation of the Viscosity of the binder of a mixture

log log Visc mix = a log log Visc1 + b log log Visc2

Where the following definitions apply: Viscmix: Viscosity of binder in new mix in Ns/m2

Example :

Visc1 = 30000, Visc2 = 2000, a = 0,25 and b = 0,75 Viscmix = 3850

Visc1 = 30000, Visc2 = 2000, a = 0,50 and b = 0,50 Viscmix = 7000


Recycled Hot Mix

Mix Design

The use of processed RAP in hot mix asphalt pavements is now

standard practice in most jurisdictions and is referenced in ASTM

D3515.

The primary steps in the design of mixes include the

determination of material properties of RAP and new materials,

the selection of an appropriate blend of RAP and virgin

aggregate to meet gradation, the selection of an appropriate

asphalt cement blend to satisfy specified viscosity and/or

penetration requirements, the need to add a recycling or

rejuvenating agent to soften the existing binder, and the

need to comply with stability, flow, and air voids

requirements.

Recycling and rejuvenating agents consist of organic compounds

derived from petroleum extracts during petroleum hydrocarbon

processing.

Procedures for selecting the quality of asphalt cement or

recycling agent are outlined in ASTM D4887.(21) This

specification includes a viscosity blending chart, which

enables the designer to determine the percentage of

recycling or rejuvenating agent in addition to soft asphalt

cement)to add to the total binder in order to achieve a

desired value of absolute viscosity for the recycled asphalt

cement.

BITUMEN Viscosity Behavior for HMA

35RAP + ACF 1000 35RAP W/O ACF 1000 RAP

Temperature

70 812 1320

80 166 276 1050

90 46 68 278

100 16 20.6 86.8

110 5.7 7.7 26

120 2.26 3.14 10

130 1.11 1.47 4.6

Graph. 3: Viscosity profiles

0,01

0,1

1

10

100

1000

10000

50 70 90 110 130 150 170 190

T /°C

Pa

.s (

log

)

RAP

35RAP

35RAP1ACF

Neat Bitumen

- RAP: 100% of aged bitumen

- 35RAP: 35% RAP in base

course: equals to 33 % of aged

bitumen and 67% of fresh binder,

without additive

- 35RAP1ACF: 35% RAP in

base course + 1% ITERLENE

ACF1000: equals to 33 % aged

bitumen +66 % bitumen + 1%

ITERLENE ACF 1000

- Neat Bitumen: "fresh"

bitumen's viscosity: reference

BITUMEN Viscosity Behavior for HMA

805

2000

500

700

900

1100

1300

1500

1700

1900

2100

60

VIS

CO

SITY

,P

a *

se

c.

°C

MECHANICAL PROPERTIES: Regenerators for HMA

Sample ID Stability

(daN)

Flow

(mm)

Stiffness

(daN/mm)

Rt

(N/mm2)

CTI

(N/mm2)

Neat Bitumen 1050 3,5 300 0,85 92

35% RAP 1303 1,9 686 1,75 210

35% RAP + 1%

ACF

1180 3,1 380 1,02 98

The effect of Iterlene ACF1000 in hot recycling is even more

evident when the mechanical stability and stiffness of the

asphalt concrete are investigated.

ITERLENE ACF 1000 reduces the stiffness of RAP –enriched

asphalts (Base Course 0/25)

RHEOLOGICAL PROPERTIES: Regenerators for HMAThe effect of Iterlene ACF1000 in hot recycling is clear when inspecting the residual Penetration and R&B

after laboratory mixing of virgin and RAP, with and without Rejuvenators. Based upon, typical test results,

ITERLENE ACF 1000, when dosed in percentage of 0.5% every 10% RAP of the added bitumen (3), the

bitumen HMA maintains similar properties of the virgin bitumen after extraction (2), while when the

ITERLENE ACF 1000 is dosed in percentage of 1%/every 10% RAP based on added virgin bitumen (5) it

maintains similar properties of the virgin bitumen before extraction (2).

Virgin Bitumen 70/100 RAP ACF 1000 Pen R&B R&B

% % % dmm °C °C

1 100 0 0 68 51 Virgin

2 100 0 0 50 60 After Extraction


4 70 30 1.5 52 61 After Extraction


Virgin Bitumen 70/100 RAP ACF 1000 Pen R&B R&B

% % % dmm °C °C

1 100 0 0 68 51 Virgin


4 70 30 1.5 52 61 After Extraction



Mechanical Properties: Regenerators for HMA


Aging Tests

Asphalt binder rheological properties will change as the binder ages. Therefore, it is important to be able to simulate aging in the laboratory so key asphalt

binder tests can be run on samples of appropriate age.

There is no direct measure for asphalt binder aging. Rather, aging effects are accounted for by subjecting asphalt binder samples to simulated aging then

conducting other standard physical tests (e.g., DSR, BBR, DTT).

Superpave PG asphalt binder aging tests are (Figure 4):

Rolling thin film oven (RTFO). Used to simulate short term aging that occurs when asphalt binder is mixed with hot aggregates in an HMA mixing

facility. The Rolling Thin-Film Oven (RTFO) procedure (Figure 1) provides simulated short term aged asphalt binder for physical property testing. Asphalt

binder is exposed to elevated temperatures to simulate manufacturing and placement aging. The RTFO also provides a quantitative measure of the volatiles

lost during the aging process. The basic RTFO procedure takes unaged asphalt binder samples in cylindrical glass bottles and places these bottles in a

rotating carriage within an oven. The carriage rotates within the oven while the 325 F (163 C) temperature ages the samples for 85 minutes. Samples are

then stored for use in physical properties tests or the PAV.

Pressure aging vessel (PAV). Used to simulate long term aging that occurs after HMA pavement construction and is generally due to environmental

exposure and loading. The Pressure Aging Vessel (PAV) (Figure 1) provides simulated long term aged asphalt binder for physical property testing. Asphalt

binder is exposed to heat and pressure to simulate in-service aging over a 7 to 10 year period. The basic PAV procedure takes RTFO aged asphalt binder

samples, places them in stainless steel pans and then ages them for 20 hours in a heated vessel pressurized to 305 psi (2.10 MPa or 20.7 atmospheres).

Samples are then stored for use in physical property tests.

Regenerators for HMAV

isco

sit

y a

t 60

C (

Pa S

) D

ina

mic

Sh

ear

Reh

om

ete

r (S

HA

RP

)

REOLOGICAL STUDY ON THE BITUMEN EXTRACTION

CARATTERIZZAZIONE

REOLOGICA DEI LEGANTI

NEI CONGLOMERATI

BITUMINOSI RICICLATI A

CALDO

Maurizio Bocci, Gianluca

Cerni, Stefano Tattolo

Istituto di Strade e Trasporti

- Università degli Studi di

Ancona

RHEOLOGICAL PROPERTIES: Regenerators for HMA

The USE of Iterlene ACF1000 is cost effective and allow great savings only considering the renewal of the

aged bitumen.

WEARING COARSE

QUANTITY 1.0 ton

RAP BITUMEN CONTENT 5.0%

TOTAL BITUMEN CONTENT 6.0%

BITUMEN PRICE 0.50 €/kg

REJUVINATOR PRICE 3.00 €/kg

REJUVINATOR QUANTITY 0.5% EVERY % OF ADDED BITUMEN / 10% RAP

RAP QUANTITY

VIRGIN

AGGREGATE RAP BITUMEN NEW BITUMEN

PRICE

BITUM

EN

SAVING

S

REJUVINATOR

QUANTITY

COST

ACF

1000

OVERALL

SAVINGS

% Kg. % Kg. % Kg. % Kg. € € % Kg. € €

10% 100 90% 900 0.5% 5.0 5.5% 55.0 27.50 2.50 0.5% 0.275 0.83 1.68

20% 200 80% 800 1.0% 10.0 5.0% 50.0 25.00 5.00 1.0% 0.500 1.50 3.50

25% 250 75% 750 1.3% 12.5 4.8% 47.5 23.75 6.25 1.3% 0.594 1.78 4.47

30% 300 70% 700 1.5% 15.0 4.5% 45.0 22.50 7.50 1.5% 0.675 2.03 5.48

40% 400 60% 600 2.0% 20.0 4.0% 40.0 20.00 10.00 2.0% 0.800 2.40 7.60

50% 500 50% 500 2.5% 25.0 3.5% 35.0 17.50 12.50 2.5% 0.875 2.63 9.88


CONCLUSIONS

•ITERLENE ACF 1000 improves the aged bitumen's rheology profile

•ITERLENE ACF 1000 guarantees the good quality of Hot Mixes produced

with high RAP recycling.

•The Hot Mix Recycling technique, needs the use of regenerators for

providing durable pavements.

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