Cd

A review on the mechanisms involved in reclaimed asphalt pavement

Lekhaz Devulapalli, Saravanan Kothandaraman*, Goutham Sarang

School of Mechanical and Building Sciences, Vellore Institute of Technology, Chennai-600127, India

Received 2 May 2018; received in revised form 5 October 2018; accepted 20 December 2018

Abstract

Reclaimed Asphalt Pavement (RAP) is a widely used recycled material in pavement construction. Whereas the integration of RAP into asphalt mixtures

is a complex subject and need to understand every aspect that entailed in the mix design. The aim of this review paper is to provide comprehensive knowledge

about the developments and challenges of the RAP in the asphalt mixtures, along with the mechanisms involved. The blending process and rejuvenator are

two key factors that govern RAP content, and this can even surge up to 100% in the asphalt mixtures. The blending between the RAP and the virgin materials

is very crucial in the context of performance and durability of RAP mixtures. While rejuvenator is an additive which may act as a catalyst and enhance the

aged RAP binder properties. A detailed description of distinct types of the rejuvenators and their performances are discussed in this paper. Several aspects

of the RAP mixtures including mix design, constituent materials, performance, RAP with polymer modified asphalt binder, as well as environmental benefits

are highlighted. This study gives information to the researchers, engineers, and designers about the RAP technology.

Keywords: Reclaimed asphalt pavement; Blending process; Rejuvenators; Recycling of asphalt pavement; RAP mix design

1. Introduction

Asphalt pavement plays an important role in the transportation

infrastructure around the world and ultimately in the global

economy [1]. In the USA and Europe, more than 90% of the roads

are surfaced with asphalt pavement, that comes around 9.0 million

km. There is about 4.0 million km of roads in Asia, 0.35 million

km of roads in Central and South America and 0.4 million km of

roads in Australia and New Zealand are asphalt paved [2,3]. These

asphalt pavements are usually laid with the asphalt mixtures.

Asphalt mixtures typically composed of about 95% natural

aggregates mixed with 5% asphalt, with asphalt functions as the

glue that binds the natural aggregates in a cohesive mix.

Aggregates used in the asphalt mixtures are naturally comprised of

crushed rock, gravel, sand, or mineral filler. Construction and

maintenance of the asphalt pavements need a continual supply of

the natural resources such as asphalt and natural aggregate.

Pavement industry annually consumes about 1.36 trillion metric

tonnes (world annual asphalt production is 1.6 trillion metric

tonnes) of asphalt [4]. These materials are non-renewable, and

their utilization eventually leads to environmental problems [5].

* Corresponding author

E-mail addresses: lekhaz.devulapalli@gmail.com (Lekhaz Devulapalli); saravanan@vit.ac.in (Dr Saravanan. K).

Peer review under responsibility of Chinese Society of Pavement Engineering.

Nowadays, there is a problem of the scarcity of asphalt and

natural aggregates, which increases their cost. Another important

challenge in the pavement industry is handling of a large volume

of materials generated through the process when the existing

asphalt pavements are removed for reconstruction or resurfacing.

The removed pavement materials are usually dumped in landfills

and that poses serious environmental concerns [6]. The removed

pavement material is known as Reclaimed Asphalt Pavement

(RAP) and it contains productive asphalt and aggregates [7]. So,

recycling and reusing of these materials are very much essential to

reduce landfills and wastage, and the same can be considered as a

step towards sustainable development [8]. Therefore, extensive

research is going on to develop and adopt alternative RAP

technologies, to reduce the consumption of and aggregates and

asphalt [9-13]. The advantages of this strategy are threefold:

reduction in the demand for asphalt and virgin aggregate, the

landfill stresses and the cost involved [14]. However, the recycling

of RAP is foreshortened, because of several problems related to

mix design guidelines, manufacturing process, durability,

pavement performance, consistency and unrealistic behaviour of

the aged RAP binder with the virgin binder [15,16]. McDaniel et

al. [17] showed the significance of the RAP content (usually

expressed by the mass of the mix) in asphalt mixtures.

Consequently, the RAP content depends on the blending process,

rejuvenators, mix design procedure, manufacturing process (plant

type, production temperature, mixing time, and discharge

ISSN: 1996-6814 DOI: https://doi.org/10.1007/s42947-019-0024-1

Chinese Society of Pavement Engineering. Production and hosting by Springer Nature

International Journal of

Pavement Research and Technology

Journal homepage: www.springer.com/42947

Chinese Society of Pavement Engineering

186 L. Devulapalli et al. / International Journal of Pavement Research and Technology 12 (2019) 185-196

FHWA- Federal Highway Administration, ETG- Expert Task Group, AASHTO-

American Association of State Highway and Transportation Officials, IRC- Indian Road

Congress.

Fig. 1. RAP evolution.

temperature), paving technology, the expected performance as

well as source and properties of the RAP.

RAP incorporated asphalt mixture is a multifaceted topic, and

the research is going since the 1970’s, as depicted in Fig. 1.

European Asphalt Pavement Association (EAPA) and National

Asphalt Pavement Association (NAPA) report stated that in

Europe 47% and the USA 60% of the available RAP is used in the

pavement construction respectively [2,18]. The annual average

RAP used in the USA is about 74 million tons in 2015 [19,20]. As

per the USA State Transportation Department (DOT) suggestion,

it is possible to use up to 30% RAP content in the intermediate

layers and surface layer of asphalt pavement construction without

compromising the performance [21]. Despite, on an average, only

12% RAP content is used in asphalt pavement which is very much

less than the average allowable limit specified by the DOT [22]. In

2014, Minnesota DOT surveyed various asphalt agencies and

asphalt mix producers, to obtain their feedback on the RAP use.

Among the responses received from 86 asphalt agencies, 55

agencies felt that RAP mixtures performed similarly to the virgin

mixtures [23]. In developing countries, the practice of RAP

incorporated asphalt mixture is not gained much attention due to

the lack of knowledge on mix design guidelines, manufacturing

process, level of interaction between aged RAP binder and virgin

binder, and field performance [24,25]. However, the recent

developments in the RAP technologies may increase the RAP

mixtures usage and make it more popular in the pavement industry.

The objective of the present paper is to provide a critical review

of recent developments and challenges in the manufacturing

process, level of interaction between aged and virgin asphalt

binders, blending process, the role of rejuvenator, mix design

procedure, incorporation of Polymer-Modified Binder (PMB), and

the performances and environmental benefits of RAP mixtures.

1.1. RAP manufacturing Process

The asphalt pavements are subjected to the continuous action of

traffic and climatic conditions along with the natural ageing of the

materials, make the pavement suffer a process of progressive

deterioration in the service life [26]. These deteriorated asphalt

pavements are to be removed through the milling process to a

certain depth [7]. The removed pavement materials are then

transported to a processing location and are crushed and processed

to reduce the maximum aggregate particle size to a manageable

size to reuse [27]. However, over-processing is avoided, which

causes the breakdown of aggregates and increases fine material

content [28]. The screening of milled RAP helps to remove the

impurities and fine materials, and the aggregates are graded

accordingly. The obtained RAP is stored free from contamination

[29]. Most importantly the quality of RAP depends on the type of

milling equipment, milling speed and depth of reclamation [30].

There are five methods of RAP recycling i.e. Hot and Cold

Recycling, Hot-in-Place Recycling, Cold-in-Place Recycling, Hot-

in-Plant Recycling and Cold-in-Plant Recycling [31].

The incorporation of RAP in asphalt plants is entirely different

from what is done generally in the laboratory. In the laboratory, it

is feasible to use high RAP (more than 30%) content because the

manufacturing conditions can be maintained easily [3,4]. Several

research studies restrict the use of high RAP content in asphalt

plants due to the issues related to the inhomogeneity of the RAP

material, manufacturing process, and plant modifications.

Overheating, ageing, quality, and source are the common problems

faced in plants, and they affect the durability of the asphalt

mixtures [32,33]. However, the RAP content up to 30% is added

in asphalt plants without any difficulties [17,22]. In order to use

RAP content above 40%, heating of the RAP is essential to ensure

enough workability [34]. In a conventional drum mix plant, 60-

70% RAP content can be processed but it is restricted to 50%,

because of the short-term ageing and gaseous emission which

occurs due to the direct exposure of RAP to the burner flame

[12,35]. In another method, the RAP is heated in a special drum

separately and then it is introduced into the virgin aggregates

gradually. This technique reduces the gaseous emission and the

short-term ageing. Commonly, superheated virgin aggregates are

added into the RAP materials. Since this process reduces the

excess oxidation of the aged RAP binder [34]. If the superheating

method is followed, the mixing time is extended to ensure proper

drying, heating, and blending between RAP and virgin materials

[36]. Whereas, conventional asphalt plants have less superheating

capacity and high gaseous emission, limiting the RAP content to

50% [37]. The asphalt plants which follow microwave technology

can allow even 100% RAP content because microwaves tend to

heat the RAP without further ageing and reduce the gaseous

emissions. But the application of this technology is limited since

the cost of heating is higher than the conventional method [35].

Another technology is to reduce the heating temperature of the

mixtures as in the case of Warm Mix Asphalt (WMA), and that

will reduce the short-term ageing and emission. This will

overcome the high cost of microwave technology and allow 100%

RAP content mixtures [33]. Zaumanis et al. [38] evaluated the

mechanical and chemical properties of the asphalt plant RAP

mixtures with rejuvenator and observed that the addition of

rejuvenator to the RAP reduced the short-term ageing and excess

heating.

Zaumanis et al. [34] reported that the milled RAP has high fine

(dust) content, and hence its usage in dense-graded asphalt mixture

may have adverse effects. Solaimanian et al. [39] concluded that

gradation of high RAP content asphalt plant produced mixtures has

finer than the target gradation. The aged RAP binder is highly

oxidized and has high stiffness compared to the virgin binder.

Hence the addition of RAP to virgin materials will alter the

mechanistic properties of the asphalt mixtures [40]. Kandhal et al.

[12] and Petersen [13] recommended to find the physical

properties of the aged RAP binder. Because the oxidation of the

RAP will alter its molecular structure and that leads to pavement

embrittlement. Huang et al. [8] stated that the fatigue performance

is the main concern in the RAP mixtures. Therefore, the study on

the characteristic behaviour of the RAP mixtures is significant.

L. Devulapalli et al. / International Journal of Pavement Research and Technology 12 (2019) 185-196 187

2. Blending process

Blending is an interaction that occurs between the RAP and

virgin binder and is a widely disputed issue which needs to be

study meticulously [22,25]. In general, the blending process can be

view as the homogenization of RAP and virgin binder after mixing

[41]. It is vital to know the blending process to produce high RAP

content mixtures [42]. Blending is a complex process and the most

crucial phase that affects the rheological properties and overall

characteristics of the RAP mixture [43]. A few researchers have

investigated the degree of blending between RAP and virgin binder

[8,17,22,44,45]. From the available studies, it is concluded that

three possible levels of bending occur between RAP and virgin

binder viz. complete blending (100% blending) [17,24,46], partial

blending [25,47] and no blending (black rock) [17,45,48] as shown

in Fig. 2.

The complete blending is assumed in the formulation of the

AASHTO M323 [46]. Al-Qadi et al. [22] and McDaniel et al. [17]

concluded that the RAP does not act like a black rock and a

significant blending occurs between the RAP and the virgin binder.

Cavalli et al. [49] stated that RAP does not completely blend with

the virgin binder but forms a layered structure coating around the

RAP aggregates. Huang et al. [8] studied the blending through

laboratory test and concluded that only some portion of aged RAP

binder participated in the blending process and the major portion

of aged RAP binder acts like a stiffer layer coated with virgin

binders. Therefore, improper blending affects the performance and

moisture induced damage of high RAP content mixtures. Only 80-

90% RAP blends with the virgin binder and the remaining do not

inherent as an active binder, leads to durability cracking and

permanent failure [22]. Whereas, Liphardt et al. [47] showed that

if the degree of blending is greater than 85%, then total blending

is assumed without compromising on the performance. Bowers et

al. [50] conducted the Gel Permeation Chromatography and

Fourier Transform Infrared Spectroscopy tests to analyze the

ageing characteristics of the RAP mixture and observed that

certain degree of blending occurs within all the layers of the

pavement mixtures, although the blending is not completely

uniform. Due to the formation of agglomerates, the aged RAP

binder and the virgin binder do not blend completely [47]. Hence

the mixing of RAP with virgin binder needs to be done carefully

[51]. The degree of blending depends also on the mixing time and

temperature. Therefore, the increase in the mixing time and

temperature improves the diffusion and provides better

homogeneity, which in return increases the stiffness modulus [50,

52, 53, 54].

Microstructural studies are performed to understand the crucial

blending process between the RAP and the virgin materials

[32,55]. It reveals that the RAP incorporation requires longer

mixing time which is about 2 to 3 times the virgin mix, to attain

the desired degree of blending [41]. Mohajeri et al. [56]

Fig. 2. Blending process.

evaluated the blending and diffusion phenomenon using

nanoindentation, Nano-Computed Tomography (Nano-CT)

scanning and optical microscopy techniques. Whereas,

nanoindentation and Nano-CT scanning are used to confirm the

blending and diffusion between the RAP and virgin binder

respectively. The optical microscopy is used to detect the interface

zone between them. Menapace et al. [55] and Oliver [44]

concluded through microstructural studies that blending process

increased by the surface roughness and decreased by the molecular

mobility of the mixture. Hence the RAP coarse aggregates are

more prone to blending with the virgin binder, than the RAP fine

aggregates [45]. Bressi et al. [57] investigated the clustering

phenomenon between the aged RAP binder and the virgin binder,

and the test results indicated that mixing temperature is pivotal for

a good degree of blending. Stimilli et al. [58] conducted the surface

area method to quantify the amount of re-activated (blending) aged

binder. It is indirectly measuring the degree of blending. Through

the microstructural analysis, Bressi et al. [57] and Rinaldini et al.

[59] detected an inconsistent degree of blending in the RAP

mixtures.

From the reported literature, it can be concluded that the RAP

incorporated asphalt mixtures show partial blending that is

somewhere between the complete blending and no blending [8,47].

Sometimes researchers neglect the partial blending and assume

complete blending, which may affect the virgin binder grade

calculation. The inappropriate blending assumption leads to the

poor fatigue and cracking resistance of high RAP content mixtures

[56]. Shirodkar et al. [25] showed a concept to find the degree of

partial blending between RAP and virgin binder. The degree of

partial blending process will help in developing a blending chart to

find the RAP content and the virgin binder content and grade as

per the given properties of the aged RAP binder.

2.1. Binder grade

The binder grade selection of virgin mixtures is determined

based on the traffic and the climatic conditions. Whereas, the

binder grade selection for the RAP mixtures, FHWA and

SuperPave Mixtures ETG suggested a three-tier system

[11,32,60,61,62]: 1) RAP content less than 15% binder grade

should be selected as the conventional mixture, 2) RAP content

between 15-25% the binder grade should be decreased by one

grade (e.g. binder grade 46-28 would be used instead of binder 52-

28) 3) RAP content more than 25 % blending charts or blending

equations are used for binder grade selection.

The binder grade selection for high RAP content mixtures

depends on the critical temperatures of aged RAP binder and virgin

binder. The desired binder grade and the physical properties of the

aged RAP binder are required to prepare a blending chart for RAP

mixture, along with any one of the following information: 1)

physical properties of the virgin binder 2) RAP content in the

mixture [36,53,62]. To find the physical properties of the RAP

binder, it is important to extract and recover the binder from the

RAP. Various extraction and recovery techniques exist such as

centrifuge, reflux, Strategic Highway Research Program (SHRP)

extractions and Recovery of Asphalt from Solution by Abson

Method - AASHTO T17, Rotavapor®, modified SHRP procedure

- AASHTO TP2 respectively. The recovered RAP binder is tested

for binder properties as per AASHTO MP1. One part of the

recovered RAP binder is tested in the Dynamic Shear Rheometer

(DSR) in the original (unaged) condition. The remaining part of

the RAP binder is aged in Rolling Thin Film Oven and tested to

188 L. Devulapalli et al. / International Journal of Pavement Research and Technology 12 (2019) 185-196

find the critical temperature using the DSR and Bending Beam

Rheometer [8,22,25,46,63]. As per the measured physical

properties and the critical temperature for the RAP binder, the

virgin binder grade will be determined as per the

assumed/designed RAP content or RAP content will be determined

as per assumed/designed virgin binder grade using blending chart

or equations.

2.2. Blending charts or equations

Blending charts or equations developed by the Asphalt Institute

are the key mechanisms to incorporate high RAP content in the

asphalt mixtures [46,53,64]. It is used to figure out the RAP

content or the virgin binder grade. McDaniel et al. [17,53]

proposed two blending approaches RAP in asphalt mixtures. In the

first approach, the appropriate virgin binder grade is determined as

per the design RAP content. In the second one, as per the design

binder grade, the appropriate RAP content is determined.

The binder from the selected RAP is extracted and

recovered as per the process discussed earlier (in section 2.1) Then

the properties of the recovered RAP binder (at critical temperature

Tc(RAP)) could be found. The DSR test is conducted to find the

critical temperature (Tc(Virgin)) of virgin asphalt and using Eqs. (1)

and (2) [17]. It is the temperature at which G*/sin(δ) and G*sin(δ)

(where complex shear modulus - G* and phase angle - δ) reach the

critical value prescribed in the SuperPave specifications. Then the

virgin binder grade that meets the temperature requirements is

selected. Fig. 3 is the high-temperature blending chart to obtain the

virgin binder grade as per the selected RAP content [22,53]

𝑇𝑐(𝐵𝑙𝑒𝑛𝑑) = 𝑇𝑐(𝑉𝑖𝑟𝑔𝑖𝑛)(1 − %𝑅𝐴𝑃) + 𝑇𝑐(𝑅𝐴𝑃) × %𝑅𝐴𝑃 (1)

𝑇𝑐(𝑉𝑖𝑟𝑔𝑖𝑛) =𝑇𝑐(𝐵𝑙𝑒𝑛𝑑)−(%𝑅𝐴𝑃 × 𝑇𝑐(𝑅𝐴𝑃))

(1−%𝑅𝐴𝑃) (2)

where, Tc(Virgin) = critical temperature of the virgin asphalt; Tc(Blend)

= critical temperature of the blended asphalt binder needed for the

climate and pavement layer temperature; %RAP = percentage of

RAP expressed in decimal; Tc(RAP) = critical temperature of the

recovered aged RAP binder.

In the second approach, the RAP content is selected as per the

design binder grade. Using Eq. (3) RAP content at the high,

intermediate, and low critical temperatures are computed [53].

Then the allowable RAP content that meets all temperature

requirement limits (low, intermediate and high-temperature) is

selected. Fig. 4 is the intermediate-temperature blending chart at

the intermediate critical temperature (Tc(RAP)) of recovered RAP

binder [22,46,53]

%𝑅𝐴𝑃 = (𝑇𝑐(𝐵𝑙𝑒𝑛𝑑)−𝑇𝑐(𝑉𝑖𝑟𝑔𝑖𝑛)

𝑇𝑐(𝑅𝑎𝑝)−𝑇𝑐(𝑉𝑖𝑟𝑔𝑖𝑛)) (3)

Even though there are several studies that addressed the degree

of the blending (complete blending, partial blending, and no

blending), researchers show contradictory statements. Whereas,

the binder grade selection guidelines of the RAP mixtures Standard

Specification for SuperPave Volumetric Mix Design - AASHTO

M323 is formulated by assuming complete blending between RAP

and virgin binder [18,42,46,62]. As of now, there is no standard

method available to figure out the degree of blending [42]. The

appropriate assumption of the blending is required to select the

optimal RAP content and virgin binder grade. It is necessary to

develop a blending chart at each level of RAP content, but it is an

intricate and time-consuming process.

Fig. 3. Blending chart for high temperature.

Fig. 4. Blending chart for intermediate temperature.

3. Rejuvenator

RAP contains stiffed aged binder and to reduce the stiffness, a

softer virgin binder may be used. However, as per many

researchers, this process does not allow high RAP content.

Whereas, the addition of rejuvenator economically permitting the

high RAP content in the mixtures [48,65]. Rejuvenator is an

asphalt additive that softens the stiffed aged binder and increases

the workability of the RAP mixtures, which can be easily paved

and compacted [66,67]. It restores the maltenes and asphaltenes

which stabilize the chemical composition of aged RAP binder

during construction and in-service. Apart from the workability,

rejuvenators are selected carefully based on the long-term and

short-term diffusion [68,69]. Carpenter and Wolosick [48] state

that the long-term diffusion process alters the properties of RAP

mixtures over a period. Whereas, short-term diffusion will occur

at once after rejuvenator is mixed and gives a homogenous uniform

coated mixture. The approximate diffusion time varies from 48-

144 hours for the rejuvenator content of 10-50% [70]. The

diffusion process should be completed before the traffic is allowed,

to increase the resistance to rutting and to avoid reduction of

friction [68]

The optimal dosage of rejuvenator is a must for the good

diffusion between RAP and virgin binder, and that envisages the

performance of the RAP mixtures [71,72]. The overdosage can

cause other problems like stripping, adhesion, rutting and thermal

cracking, whereas the insufficient amount will make the mixture

stiffer [73,74,75]. Shen and Tang [76] states that the rutting

resistance of RAP mixtures decreased linearly as the rejuvenator

percentage increased. Therefore, it is vital to know the optimal

percentage of rejuvenator needed in the mixture and is determined

from Eq. (4) [73].

50

60

70

80

90

0 10 20 30 40 50 60 70 80 90 100

Tcr

itic

al (

˚C)

RAP Content (%)

10

15

20

25

30

35

0 10 20 30 40 50 60 70 80 90 100

Tcr

itic

al (

˚C)

RAP Content (%)

L. Devulapalli et al. / International Journal of Pavement Research and Technology 12 (2019) 185-196 189

𝑃 =(4𝐶+7𝑆+12𝐹)×𝐶𝐹

100 (4)

where, P= percentage of rejuvenator; C= percentage of aggregate

retained on 2.36 mm sieve; S= percentage passing 2.36 mm sieve

and retained on 0.075 mm sieve; F= percentage passing 0.075 mm

sieve; CF = compensating factor for the impurities in the mixtures

(normally CF=1.2).

Lin et al. [77] state that a good rejuvenator is the one which reacts

effectively with the aged RAP binder and meets both the short-

term and the long-term diffusion criteria and produces a high-

performance RAP mixture. Baghaee and Baaj [9] concluded that

the optimal rejuvenator dosage varies with respect to the

rejuvenator type, and RAP content and source. Table 1. present

different of rejuvenators used in the RAP mixtures.

Table 1

Rejuvenators and performances.

S.no Rejuvenator Reference

Type Name Dosage Performance*

1 Petroleum-

Based,

Generic Product

Petroleum-Tech 6.2% Weight of Binder. High Cracking Resistance, Less Stiffness [72]

Aromatic Extract 12% Weight of Binder. Low Fatigue Resistance Compared to virgin

mixtures

[78]

18% Weight of Binder. Low-temperature Creep, High Tensile Strength and

Fracture Energy Performance.

[28]

Pongamia Oil 5% Weight of Binder Better Fatigue Performance and Desirable Rutting

Resistance

[79]

Paraffinic Base Oil 18% Weight of Binder. Performed Better under Low-Temperature Creep

and Fracture Energy.

[28]

Naphthenic Flux Oil Failure in Penetration Index.

Waste Engine Oil Bottom Failure in Penetration Index.

Waste Engine Oil 12% Weight of Binder. Less Fatigue Resistance and Low-Temperature Cracking.

[78]

18% Weight of Binder Failure in Penetration Index. [28]

5.4% Weight of Binder Less Brittle and less Indirect Tensile Strength [80]

Aromatic Oil No information High Fatigue Resistance [79]

C** 300 g/m2 Less ductility, Poor Performance. [71]

J** Penetration depth is 10-20mm, High Ductility.

L** Penetration depth is 10-20mm, High Performance.

2 Organic-

Based, Generic

Product

Waste Vegetable Oil 12% Weight of Binder. Performed Better than the virgin mixture and

showed negative results for Low-Temperature Cracking.

[78,81]

5.1% Weight of Binder. Less brittle and more Durable than conventional

mixtures.

[80]

Waste Vegetable Oil

(Refined)

3-4% Weight of Binder. Performed like the conventional mixtures. [82]

Waste Vegetable Grease 12% Weight of Binder. Performed better than a virgin mixture, Showed negative results for Low-Temperature Cracking.

[78]

Distilled tall Oil Resistance to Low-Temperature Cracking and

prone to Fatigue Failure. Refined Tallow 9% Weight of Binder. Low-temperature Creep, Tensile Strength and

Fracture Energy Performance.

[28]

Distilled Tall Oil Performed better in Low-Temperature Creep, Tensile Strength, and Fracture Energy.

Vegetal Oil-VO- No information Increased complex modulus parameter G* [83] 3 Engineered,

Organic

Product

Organic Blend 9% Weight of Binder. Low-temperature Creep, Tensile Strength and

Fracture Energy Performance.

[28]

Organic Oil 12% Weight of Binder. Superior Low-Temperature Cracking and overall Performance are Better than Virgin mixtures.

[78]

Castor Oil 5% Weight of Binder Desirable Rutting and Fatigue Behaviour [79]

4 Commercial Green-Tech (Tall oil) 8.2% Weight of Binder. High Stiffness, Less Cracking Resistance [72]

Agriculture-Tech (Soybean

oil)

1.6% Weight of Binder. High Stiffness, Moderate Cracking Resistance.

Sasol Sorbitol Plus 18% Weight of Binder. Failure in penetration index. [28]

ANOVA No information Improved low-temperature Cracking and Rutting

Resistance.

[84]

Revive™ No information Improved low-temperature cracking. [85]

Cyclogen® L No information Improved low-temperature cracking. [86]

BituTech RAP 5.218% Weight of Binder. Performed better towards Rutting, Less Moisture

Susceptibility. Revisit dosage.

[87]

SonneWarmix RJT

SonneWarmix RJ

Reclamite As per manufacture recommendation

Lowered the Stiffness of RAP. [88]

Aromatic oil (PetroPlus

Refining Antwerp)

2-10% Weight of Binder. Penetration value increase as the microcapsule %

increases. Softening point reduces with an addition of microcapsule.

[89]

* All the performances are compared with the reference mixture in their respective studies. **No specific name is mentioned by the author.

190 L. Devulapalli et al. / International Journal of Pavement Research and Technology 12 (2019) 185-196

3.1. Mixing of rejuvenator

The mixing of the rejuvenator to the RAP mixtures is a

significant procedure, while improper mixing will subside the

rejuvenator effect. Several research reports showed that there are

many unstandardized mixing processes of rejuvenator into the

RAP mixtures [48, 73]. Direct mixing of a rejuvenator to the RAP

mixtures at the mixing temperature is the most common way of

adding rejuvenator [38,84,90]. Some researchers mix the

rejuvenator with the RAP aggregate, while a few researchers mix

it with the combined aggregate (mix of virgin and RAP aggregate)

[9,80]. Tran et al. [86] suggested that the rejuvenator should be

added to the virgin binder, and then it should be mixed with the

combined aggregates. The mixing of the rejuvenator directly to the

RAP material will give the better results, but this process is

difficult to implement in the asphalt plant [86,87].

4. Mix design of RAP

To achieve a quality RAP mixture, the constituent materials

should meet the specifications suggested by various agencies like

AASHTO, IRC, American Society for Testing and Materials

(ASTM), etc. [91]. The mix design procedure of RAP mixtures is

the same as the conventional asphalt mix design [46,17]. But care

is taken while the selection of the binder grade/RAP content,

mixing the RAP and the rejuvenators and the proper mixing is

ensured to produce a homogenous and consistent mixture. The

properties of the constituent materials are determined prior to

mixing. Firstly, the RAP binder is extracted from the RAP. The

binder extracted RAP aggregate and the virgin aggregate are tested

for determination of coarse aggregate angularity, impact value,

abrasion value, flakiness and gradation requirements. The

recovered RAP binder and the virgin binder are also tested for the

physical properties as per the specification [46,92].

The gradation of aggregates is vital in the asphalt mixtures that

will help to form a uniform and robust mixture. The gradation

limits are followed as per the specifications provided by the

respective agencies. However, there is no separate gradation

specification for the RAP mixture [46,64,92,93]. The binder grade

for the RAP mixtures is selected as per the process discussed

earlier (in section 2.1). It is necessary to adjust the virgin binder

grade accordingly for high RAP content, and then the blending

charts or equations are used to determine the RAP content or the

virgin binder grade [17,53,64,94,95].

In case of high RAP content mixtures, the amount of RAP added

into the asphalt mixture is based on the RAP binder ratio, the ratio

of the binder present in the RAP divided by the total binder content

and is calculated from Eq. (5) [17]. Then the required RAP content

and the virgin materials are mixed as per the standard asphalt mix

design specifications (Marshall or SuperPave method). In the mix

design process, the RAP material is heated before mixing with the

virgin materials. Overheating should be avoided to prevent the

excessive ageing of the RAP binder [62,78]. All the materials

should be mixed properly at a suitable temperature to attain a good

degree of blending and homogenous mixture. Rejuvenator is added

as per the required quantity to the mixture. There is no standard

procedure available on the rejuvenator mixing, but many

researchers follow the direct application of rejuvenator when the

mixture is in hot condition [9]. Conventional Marshall compaction

or gyratory compaction procedures can be followed as per the

specifications.

𝑅𝐴𝑃𝑏𝑟 =𝑃𝐵𝑅𝐴𝑃× 𝑃𝑅𝐴𝑃

(𝑃𝐵𝑇𝑜𝑡𝑎𝑙) (5)

where, RAPbr = RAP binder ratio; PBRAP = Weight of RAP binder

content; PBTotal = Total binder content in the mixture; PRAP =

Percentage of RAP by weight of the mixture.

To attain a high-performance mixture, the volumetric properties

of the RAP mixture should meet the required specifications

[22,94]. Marshall or SuperPave method of mix design is followed

to find out the Voids in Mineral Aggregates (VMA), voids filled

with asphalt, air voids, dust proportion, Marshall stability and flow

value. The bulk and effective specific gravity (Gse) of the

combined aggregates are calculated as per Eqs. (6) and (7) [10]. If

the source of RAP material is known, then the known bulk specific

gravity (Gsb) is used to calculate Gse. Otherwise, it is obtained by

doing the back calculation from the maximum theoretical specific

gravity (Gmm) (tested as per ASTM D-2041) [94,95]. The accurate

calculation of the Gsb is very important in the mix design. The Gse

is used for the calculations of the VMA, and some researchers use

to correct the Gse to an estimated Gsb with an assumed binder

absorption value [53,95]. However, West et al. [62] stated that the

assumption of binder absorption is very sensitive, and the

inaccurate assumption leads to an error in the VMA calculation.

They recommended that the solvent extracted, and the recovered

RAP aggregates are to be tested for the coarse and fine aggregate

specific gravities (Gsb). Then the optimum asphalt content is

determined based on the specifications and the type of the mixture

[53,94].

𝐺𝑠𝑒 =100−𝑃𝑏100

𝐺𝑚𝑚−

𝑃𝑏𝐺𝑏

(6)

𝐺𝑠𝑏 = 𝐺𝑠𝑒

(𝐺𝑠𝑒𝑃𝑏𝑎100𝐺𝑏

+1) (7)

where, Gse = aggregates effective specific gravity; Gsb = bulk

Specific gravity of aggregates; Gmm = theoretical maximum

specific gravity of the mixture; Gb = specific gravity of RAP

binder; Pb = RAP binder content; Pba = absorbed binder.

5. RAP performance

The comprehensive RAP mixture is achieved only if it satisfies

the filed performance criteria. Paul [96] conducted field

performance tests on virgin and 10-40% RAP content pavement

sections. The serviceability, pavement conditions, visual

conditions and structural analysis over 6-8 years old pavements are

studied and found no significant difference between them.

Mohammad et al. [97] concluded that the long-term performance

of RAP mixtures is better compared with the conventional asphalt

mixtures. Kandhal et al. [98] studied 1-2.5 years’ service period of

pavement test sections with 10-25% of RAP content, and have not

observed any indication of rutting, fatigue cracking and

weathering. Zaghloul and Holland [99] evaluated the long-term

performance of 47 pavement test sections over California and the

results showed that the RAP mixtures performed comparatively

with the conventional mixtures. In 2009, national centre asphalt

technology constructed test sections with 45% RAP content and at

the end of 2 years, the performance test results showed only 3 mm

of rutting [100].

It is significant to know the laboratory performance of the

RAPmixture, to assure that the mixture can resist the rutting,

thermal cracking, moisture and fatigue [101]. According to Al-

Qadi et al. [22], there are no substantial differences in the

mechanical properties of the RAP and conventional asphalt

L. Devulapalli et al. / International Journal of Pavement Research and Technology 12 (2019) 185-196 191

mixtures. Resilient modulus tests indicated that the asphalt mixture

with 20% RAP shows similar stiffness compared to that of the

virgin mixture [97,102,103,104,105]. The highly oxidized RAP

binder aged at a slower rate than the virgin mixtures, decelerating

the rate of hardening and the mixture showed better moisture

resistance [106,107]. Reyes-Ortiz et al. [108] evaluated 100%

RAP added mixtures and obtained high indirect tensile strength.

Coffey et al. [109] and Ghabchi et al. [110] concluded that RAP

mixtures exhibit minimal rutting. The dynamic modulus increases

with increase in the RAP content and gets value similar to that of

the virgin mixture [111]. Research studies showed that use of

certain RAP content increased the performance of RAP mixtures

[29,94,26,81,111]. But some researchers observed negative results

for the fatigue performance and cumulative stress rate of RAP

mixtures [8,112,113].

6. RAP in polymer-modified binder

The main role of PMB is to increase the resistance of asphalt

mixtures towards high-temperature cracking, without any adverse

effects on the low-temperature properties [114,115]. The usage of

the PMB is increased with the development in technology, due to

the need of a new binder and suitable for heavy traffic load. That

enforced the incorporation of the same in RAP mixtures. Many

research studies claim that the incorporation of the RAP with PMB

is completely different from the methods done using conventional

asphalt [116,117,118]. It is observed that conventional RAP may

be incorporated with PMB or PMB-RAP may be incorporated with

conventional asphalt mixtures. For instance, RAP obtained from

high-traffic roads (highways or freeways) may contain PMB, and

that limits the binder oxidation which benefits the asphalt mixture

[116]. Singh et al. [119] and Bernier et al. [120] studied the

performance of the mixtures having different level of RAP

contents with PMB and found improved rutting resistance. Kim et

al. [117] investigated the effect of RAP contents with Styrene-

Butadiene-Styrene PMB and results indicated better performance

irrespective of the RAP content in the mixture. The RAP

incorporated conventional asphalt mixtures showed cracking

problems but the mixtures with 30% RAP content and Styrene-

Butadiene-Styrene PMB exhibited high cracking resistance [121].

It is showed that the incorporation of PMB in RAP mixtures

increased the binder stiffness and improved temperature

susceptibility [117,118]. Shen et al. [122] investigated the

laboratory prepared PMB-RAP mixtures by SuperPave recycling

and the same is incorporated into the virgin mixture. The test

results exhibited that 15% RAP content can be incorporated with

PMB. Singh et al. [123] confirmed that different RAP sources and

contents influenced the performance of mixtures with PMB and

the increase in RAP content leads to premature failure. The

Multiple Stress Creep Recovery (MSCR) test (as per AASHTO T-

350) gives more accurate idea about the viscoelastic behaviour of

the PMB-RAP mixtures, compared to the conventional DSR test

[121,124,114]. Singh et al. [123] evaluated mixtures having four

RAP contents with PMB and the linear amplitude sweep test

results indicated that increase in the RAP content caused a

decrease in fatigue life.

7. Environmental benefits.

Apart from the economic point of view, RAP also offers different

environmental benefits. Lee et al. [125] concluded that 30% RAP

mixtures emit only 80% of CO2 and requires 84% of energy

compared to the conventional asphalt mixtures. RAP in the

pavement construction is indeed a good method of saving the

energy and reducing the CO2 emission. Aurangzeb et al. [126]

conducted the life cycle assessment on high RAP content Hot Mix

Asphalt (HMA) and showed that RAP incorporated HMA

mixtures reduce 28% of energy consumption and Greenhouse

Gases emission compared to the conventional HMA. The RAP

mixtures with 30%, 40%, and 50% show an energy reduction of

26%, 33%, and 40% respectively [127,128,129]. Chiu et al. [7]

conclude that the RAP reduced the asphalt content and that in

return lower the eco-burden. Jamshidi et al. [129] performed the

preliminary evaluation of the fuel requirement and Greenhouse

Gases emission of RAP mixtures and observed that RAP mixtures

are helpful in the context of sustainability to produce cleaner

asphalt mixtures. According to Silva et al. [130] RAP is a better

alternative to road paving material, predominantly if rejuvenators

are used to reduce the production temperature and to improve the

mixture performance. The life cycle analysis of RAP shows that

there is a reduction in global warming potential, energy

consumption and hazardous waste generation [125]. Vidal et al.

[131] state that the environmental benefits from the RAP are

higher than the WMA technologies.

8. Conclusion

This paper presents a detailed literature review concerning the

RAP in the asphalt mixtures and provides information about the

RAP manufacturing process, blending charts or equations, degree

of blending, microstructural analysis different types of

rejuvenators, optimum rejuvenator dosage, the field and laboratory

performances, RAP with PMB mixtures and its environmental

benefits. RAP is very advantageous in the context of the

environmental friendliness and sustainability, thereby, the benefits

of RAP should be utilized as much as possible in the pavement

construction. It is observed that researchers are trying every viable

way to incorporate RAP into asphalt mixtures. However, there are

certain subtle challenges that needed to be mitigated in order to

obtain a rich RAP mixture.

Many researchers claimed that the asphalt plant manufacturing

process of the RAP incorporated asphalt mixtures is different from

the laboratory process because of acute confronts in the former

process. However, RAP content up to 30% can be incorporated

without much difficulties in the asphalt plants. Several studies

confirmed that the blending process depends on the mixing

temperature and time. It is evident that the blending process is not

precisely addressed. The recent microstructural studies relieve that

the blending is not uniform in the RAP incorporated asphalt

mixtures, and this non-uniform blending process may lead to other

performance problems. The blending charts or equations provide

the information about the RAP content or virgin binder grade

required in the asphalt mixture and their choice accordingly, but

the complexity put its usage at stake. However, a few research

studies concluded that the degree of partial blending is neglected

in the design of the blending charts.

Rejuvenators may be helpful in manufacturing 100% RAP

mixtures, by activating the aged RAP binder and will surge the

RAP content exponentially in the asphalt mixtures. In return, the

workability and fatigue performance of the mixture increase

without altering the rutting performance. Careful selection of

rejuvenator and dosage is essential for a good quality asphalt

mixture with high performance, whereas, the information about the

mixing of rejuvenator may not pertain. Consequently, the issues

192 L. Devulapalli et al. / International Journal of Pavement Research and Technology 12 (2019) 185-196

related to the mixing of rejuvenator to the RAP mixtures need to

be focused more. Out of different rejuvenators tried by researchers,

waste vegetable oil and a few commercial rejuvenators blended

RAP mixtures are observed to perform better than the virgin

mixtures.

The asphalt mixtures with RAP content less than 30% have

performed as good as the conventional mixtures, but when the

RAP content increases, the mixtures showed inconsistent

performance. There is no compelling evidence available to support

the hypotheses of blending charts or equations for blending and for

fixing the rejuvenator contents. Several research studies showed

that the mix design criteria for the RAP mixtures are as same as

the conventional mixtures. Considerable care should be taken in

the selection of RAP content, virgin binder grade, rejuvenator

dosage, and mixing time and temperature. The RAP mixtures with

PMB improved the rutting resistance and displayed inconsistent

fatigue performance. It is vital to produce a consistent RAP

mixture with least contingency that will encourage the asphalt

industry to use RAP in the asphalt mixtures without any hesitation.

Reference

[1] M. Mangum, Asphalt Paving Sector Presentation. In Health

Effects of Occupational Exposure to Emissions from

Asphalt/Bitumen Symposium. Dresden, Germany, 2006.

[2] European Asphalt Pavement Association. Asphalt in figure.

EAPA, Brussels, Belgium, 2011.

[3] EAPA NAPA. The Asphalt Paving Industry: A Global

Perspective, 3rd Edition, Production, Use, Properties, and

Occupational Exposure Reduction Technologies and Trends,

Lanham, MD. U.S.A., 2011.

[4] Asphalt Institute, European Bitumen Association -

Eurobitume. Production, Chemistry, Use, Specification and

Occupational Exposure, The Bitumen Industry, A Global

Perspective 1st ed, Lexington, KY, 2008.

[5] J. R. Bukowski, Guidelines for the Design of Superpave

Mixtures Containing Reclaimed Asphalt Pavement (RAP).

In Memorandum, ETG Meeting, FHWA Superpave

Mixtures Expert Task Group, San Antonio, TX, 1997.

[6] S. Saride, D. Avirneni, S. C. P. Javvadi, Utilization of

reclaimed asphalt pavements in Indian low-volume roads, J.

Mater. Civ. Eng. 28 (2) (2015) 04015107.

[7] C. T. Chiu, T. H. Hsu, W.F. Yang, Life cycle assessment on

using recycled materials for rehabilitating asphalt

pavements, Res. Conserv. Recycling. 52 (2008) 545–556.

[8] B. Huang, G. Li, D. Vukosavljevic, X. Shu, B. Egan,

Laboratory investigation of mixing hot-mix asphalt with

reclaimed asphalt pavement, Transp. Res. Rec.1929 (2005).

37-45.

[9] T. B. Moghaddam, H. Baaj, The use of rejuvenating agents

in production of recycled hot mix asphalt: A systematic

review, Constr. Build. Mater. 114 (2016) 805–816.

[10] A. Copeland, Reclaimed asphalt pavement in asphalt

mixtures: State of the practice. Federal Highway

Administration, Washington, DC, 2011.

[11] T. W. Kennedy, W. O. Tam, M. Solaimanian, Effect of

reclaimed asphalt pavement on binder properties using the

superpave system, Work 1250 (1) (1998).

[12] P. S. Kandhal, F. Parker, R. B. Mallick, Aggregate tests for

hot-mix asphalt: state of the practice. Transportation

Research Board, National Research Council, Washington,

D.C., U.S.A., 1997.

[13] J. C. Petersen, Chemical composition of asphalt as related to

asphalt durability: State of the art, Transp. Res. Rec. 999

(1984) 13–30.

[14] J. J. Yang, P. T. A. Lakte, S. H. Kim, Use of conditional

inference trees for evaluating the effect of reclaimed asphalt

pavement content and binder grade on the dynamic modulus

of asphalt concrete mixtures, Inter. J. Pave. Res. Tech.

(2018).

[15] R. McDaniel, R. M. Anderson, Recommended use of

reclaimed asphalt pavement in the superpave mix design

method: guidelines. No. 253. Transp. Res. Brd., National

Research Council, Washington, D.C., U.S.A., 2001.

[16] R. West, A. Kvasnak, N. Tran, B. Powell, P. Turner, Testing

of moderate and high reclaimed asphalt pavement content

mixes: laboratory and accelerated field performance testing

at the national center for asphalt technology test track,

Transp. Res. Rec. 2126 (2009) 100-108.

[17] R. S. McDaniel, H. Soleymani, R. M. Anderson, P. Turner,

R. Peterson, Recommended use of reclaimed asphalt

pavement in the Superpave mix design method. NCHRP

Web document, 30 2000.

[18] K. R. Hansen, A. Copeland, Annual asphalt pavement

industry survey on recycled materials and warm-mix asphalt

usage. No. IS-138, Lanham, MD. U.S.A, 2013 2009–2012.

[19] K. R. Hansen, A. Copeland, Asphalt pavement industry

survey on recycled materials and warm-mix asphalt usage:

2014. No. IS-138. Lanham, MD. U.S.A., 2015.

[20] R. West, A. Copeland, High RAP asphalt pavements: Japan

practice: Lessons learned. NAPA Rep. No. IS, 139, Lanham,

MD. U.S.A 2015.

[21] A. Copeland, Reclaimed asphalt pavement in asphalt

mixtures: State of the practice, Federal Highway

Administration, Washington DC., USA., 2011.

[22] I. L. Al-Qadi, M. Elseifi, S. H. Carpenter, Reclaimed asphalt

pavement: a literature review, Illinois Centre of

Transportation, Springfield, IL, 2007.

[23] R. Kuehl, J. Korzilius, M. Michael, Synopsis of Recycled

Asphalt Pavement (RAP) Material. National Technical

Information Services, Springfield, Virginia, USA., 22161

2016.

[24] T. A. Pradyumna, A. Mittal, P. K. Jain, Characterization of

Reclaimed Asphalt Pavement (RAP) for Use in Bituminous

Road Construction. Proc. Soc. Behav. Sci. 104 (2013) 1149–

1157.

[25] P. Shirodkar, Y. Mehta, A. Nolan, K. Sonpal, A. Norton, C.

Tomlinson, R. Sauber, A study to determine the degree of

partial blending of reclaimed asphalt pavement (RAP) binder

for high RAP hot mix asphalt, Constr. Build. Mater. 25 (1),

(2011) 150-155.

[26] European Asphalt Pavement Association, Asphalt in Figures

2014. Brysseli: European Asphalt Pavement Association,

Brussels, Belgium, 2016.

[27] J. S. Daniel, A. Lachance, Mechanistic and volumetric

properties of asphalt mixtures with recycled asphalt

pavement, Transp. Res. Rec. 1929 (1) (2005) 28-36.

[28] M. Zaumanis, R. Mallick, R. Frank, Evaluation of

Rejuvenator's Effectiveness with Conventional Mix Testing

for 100% Reclaimed Asphalt Pavement Mixtures, Transp.

Res. Rec. 2370 (2013) 17-25.

[29] Y. Huang, R. Bird, B. Allen, A life cycle assessment tool for

recycling in pavement construction. In SETAC Europe 13th

L. Devulapalli et al. / International Journal of Pavement Research and Technology 12 (2019) 185-196 193

LCA Case Study Symposium with Focus on the Building and

Construction Sector, Stuttgart, Germany, 2006.

[30] E. V. D. Kerkhof, Warm waste asphalt recycling in belgium:

30 years of experience and full confidence in the future. In

5th Euroasphalt and Eurobitume congress, Istanbul, Turkey,

2012 13-15.

[31] Indian Roads Congress, Recommended practice for

recycling of bituminous pavements. IRC:120-2015. New

Delhi, India, 2015.

[32] B. Hofko, A. Cannone Falchetto, J. Grenfell, L. Huber, X.

Lu, L. Porot, Z. You, Effect of short-term ageing

temperature on bitumen properties, Road Mater. Pave. Des.

18 (sup2) (2017) 108-117.

[33] H. Sivilevičius, J. Bražiūnas, O. Prentkovskis, Technologies

and Principles of Hot Recycling and Investigation of

Preheated Reclaimed Asphalt Pavement Batching Process in

an Asphalt Mixing Plant, Appl. Sci. 7 (11) (2017) 1104.

[34] M. Zaumanis, R. B. Mallick, R. Frank, 100% recycled hot

mix asphalt: A review and analysis. Resources, Conserv.

Recycling 92 (2014) 230-245.

[35] R. Hassan, Feasibility of using high RAP contents in hot mix

asphalt. In 13th International Flexible Pavements

Conference. Australian Asphalt Pavement Association,

Queensland, Australia, 2009.

[36] I. L. Howard, AL. Cooley Jr, J.D. Doyle, Laboratory testing

and economic analysis of high rap warm mixed asphalt.

Jackson: Mississippi Department of Transportation.

FWHA/MS-DOT-RD-09-200., Mississippi, U.S.A., 2009.

[37] Transportation Research Board (TRB), Mix Design Practices

for Warm Mix Asphalt. NCHRP 09-43. Washington, D.C.,

U.S.A., 2009.

[38] M. Zaumanis, M. C. Cavalli, L. D. Poulikakos, Effect of

rejuvenator addition location in plant on mechanical and

chemical properties of RAP binder, Inter. J. Pave. Eng.

(2018) 1-9.

[39] M. Solaimanian, E. Savory, Variability analysis of hot-mix

asphalt concrete containing high percentage of reclaimed

asphalt pavement, Transp. Res. Rec. (1543) (1996) 89-96.

[40] D. Kim, A. Norouzi, S. Kass, T. Liske, Y.R. Kim,

Mechanistic performance evaluation of pavement sections

containing RAP and WMA additives in Manitoba, Constr.

Build. Mater. 133 (2017) 39–50.

[41] J. Navaro, D. Bruneau, I. Drouadaine, J. Colin, A. Dony, J.

CournetObservation and evaluation of the degree of blending

of reclaimed asphalt concretes using microscopy image

analysis, Constr. Build. Mater. 37 (2012) 135–143.

[42] P. Kriz, D. L. Grant, B. A. Veloza, M. J. Gale, A. G. Blahey,

J. H. Brownie, R. D. Shirts, S. Maccarrone, Blending and

diffusion of reclaimed asphalt pavement and virgin asphalt

binders, Road Mater. Pave. Des. 15 (2014) 78–112.

[43] K. Zhang, B. Muhunthan, Effects of production stages on

blending and mechanical properties of asphalt mixtures with

reclaimed asphalt pavement, Constr. Build. Mater. 149

(2017) 679-689.

[44] J. W. Oliver, The influence of the binder in RAP on recycled

asphalt properties, Road Mater. Pave. Des. 2 (3) (2001) 311-

325.

[45] J.E. Stephens, J. M. Mahoney, C. Dippold, Determination of

the PG Binder Grade to Use in a RAP Mix. No. JHR 00-278.

Connecticut Transportation Institute, University of

Connecticut, School of Engineering, 2001.

[46] American Association of State Highway and Transportation

Officials, Standard specification for Superpave volumetric

mix design. M. 323-13. 2013. AASHTO, Washington, D.C.,

U.S.A., 2013

[47] A. Liphardt, P. Radziszewski, J. Król, Binder blending

estimation method in hot mix asphalt with reclaimed asphalt,

Proc. Eng. 111 (2015) 502-509.

[48] S. H. Carpenter, J. R. Wolosick, Modifier influence in the

charaterization of hot-mix recycled material, Transp. Res.

Rec. 177 (1980) 15-22.

[49] M. C. Cavalli, M. N. Partl, L. D. Poulikakos, Measuring the

binder film residues on black rock in mixtures with high

amounts of reclaimed asphalt, J. Cleaner Prod. 149 (2017)

665-672.

[50] B.F. Bowers, J. Moore, B. Huang, X. Shu, Blending

efficiency of Reclaimed Asphalt Pavement: An approach

utilizing rheological properties and molecular weight

distributions. Fuel 135 (2014) 63–68.

[51] J. S. Chen, C. H. Wang, C. C. Huang, Engineering Properties

of bituminous mixtures blended with second Reclaimed

Asphalt Pavements (R2AP), Road Mater. Pave. Des. 10,

(2009) 129–149.

[52] M. Zaumanis, R. B. Mallick, Review of very high-content

reclaimed asphalt use in plant-produced pavements: state of

the art, Inter. J. Pave. Eng. 16 (1) (2015) 39-55.

[53] F. Y. Rad, N. R. Sefidmazgi, H. Bahia, Application of

diffusion mechanism: Degree of blending between fresh and

recycled asphalt pavement binder in dynamic shear

rheometer, Transp. Res. Rec. 2444 (1) (2014) 71-77.

[54] H. V. Nguyen, Effects of mixing procedures and rap sizes on

stiffness distribution of hot recycled asphalt mixtures,

Constr. Build. Mater. 47 (2013) 728–742.

[55] I. Menapace, L. G. Cucalon, F. Kaseer, E. Arámbula-

Mercado, A. E. Martin, E. Masad, G. King, Effect of

recycling agents in recycled asphalt binders observed with

microstructural and rheological tests, Constr. Build. Mater.

158 (2018) 61–74.

[56] M. Mohajeri, A. A. A. Molenaar, M. F. C. Van de Ven,

Experimental study into the fundamental understanding of

blending between reclaimed asphalt binder and virgin

bitumen using nanoindentation and nano-computed

tomography, Road Mater. Pave. Des. 15 (2) (2014) 372-384.

[57] S. Bressi, M. C. Cavalli, M. N. Partl, G. Tebaldi, A. G.

Dumont, L. D. Poulikakos, Particle clustering phenomena in

hot asphalt mixtures with high content of reclaimed asphalt

pavements, Constr. Build. Mater. 100 (2015) 207-217.

[58] A. Stimilli, A. Virgili, F. Canestrari, New method to

estimate the “re-activated” binder amount in recycled hot-

mix asphalt, Road Mater. Pave. Des. 16 (sup1) (2015) 442-

459.

[59] E. Rinaldini, P. Schuetz, M. N. Partl, G. Tebaldi, L. D.

Poulikakos, Investigating the blending of reclaimed asphalt

with virgin materials using rheology, electron microscopy

and computer tomography. Composites Part B: Eng. 67

(2014) 579-587.

[60] S. Yu, S. Shen, X. Zhou, X. Li, Effect of Partial Blending on

High-Content RAP Mix Design and Mixture Properties.

Transp. Res. Rec. 2672 (28) (2018) 79-87.

[61] L. Noferini, Investigation on performances of asphalt

mixtures made with reclaimed asphalt pavement: effects of

interaction between virgin and rap bitumen. Inter. J. Pave.

Res. Tech. 10 (4) (2017) 322-332.

194 L. Devulapalli et al. / International Journal of Pavement Research and Technology 12 (2019) 185-196

[62] R.C. West, J.R. Willis, M.O. Marasteanu, Improved mix

design, evaluation, and materials management practices for

hot mix asphalt with high reclaimed asphalt pavement

content, Transp. Res. Brd. NCHRP Report No.752,

Washington, D.C., U.S.A., 2013.

[63] R. McDaniel, H. Soleymani, A. Shah, Use of reclaimed

asphalt pavement (RAP) under Superpave specifications: A

regional pooled fund project., FHWA?IN?JTRP-2002/6.

West Lafayette, IN, U.S.A., 2002.

[64] European Standard, Bituminous Mixtures–Material

Specifications–Part, 8. C. 13108–8. Brussels, Belgium,

2005.

[65] E. Arámbula-Mercado, F. Kaseer, A. E. Martin, F. Yin, L.

G. Cucalon, Evaluation of recycling agent dosage selection

and incorporation methods for asphalt mixtures with high

RAP and R AS contents, Constr. Build. Mater. 158 (2018)

432–442.

[66] S. Mangiafico, H. Di Benedetto, C. Sauzéat, F. Olard, S.

Pouget, L. Planque, Relations between Linear ViscoElastic

Behaviour of Bituminous Mixtures Containing Reclaimed

Asphalt Pavement and Colloidal Structure of Corresponding

Binder Blends, Proc. Eng. 143 (2016) 138–145.

[67] R. L. Terrel, J. A. Epps, Using additives and modifiers in hot

mix asphalt. Section A (No. QIP-114A)., Lanham,

Maryland, U.S.A.,1989

[68] R.B. Mallick, R. Frank, 100% Hot Mix Asphalt Recycling:

Challenges and Benefits, Transp. Res. Proc. 14 (1989)

(2016) 3493–3502.

[69] T. Blomberg, M. Makowska, T. Pellinen, Laboratory

Simulation of Bitumen Aging and Rejuvenation to Mimic

Multiple Cycles of Reuse, Transp. Res. Proc. 14 (2016) 694–

703.

[70] R. Karlsson, U. Isacsson, Application of FTIR-ATR to

characterization of bitumen rejuvenator diffusion, J. Mater.

Civ. Eng. 15 (2) (2003) 157-165.

[71] J. Lin, J. Hong, C. Huang, J. Liu, S. Wu, Effectiveness of

rejuvenator seal materials on performance of asphalt

pavement, Constr. Build. Mater. 55 (2014) 63–68.

[72] H. Nabizadeh, H.F. Haghshenas, Y.R. Kim, F.T.S. Aragão,

Effects of rejuvenators on high-RAP mixtures based on

laboratory tests of asphalt concrete (AC) mixtures and fine

aggregate matrix (FAM) mixtures, Constr. Build. Mater. 152

(2017) 65–73.

[73] M. Zaumanis, R. B. Mallick, R. Frank, Determining

optimum rejuvenator dose for asphalt recycling based on

Superpave performance grade specifications, Constr. Build.

Mater. 69 (2014) 159-166.

[74] S. Im, P. Karki, F. Zhou, Development of new mix design

method for asphalt mixtures containing RAP and

rejuvenators, Constr. Build. Mater. 115 (2016) 727-734.

[75] P. Cong, H. Hao, Y. Zhang, W. Luo, D. Yao, Investigation

of diffusion of rejuvenator in aged asphalt, Inter. J. Pave.

Res. Tech. 9 (2016) 280–288.

[76] J. Shen, S. Amirkhanian, B. Tang, Effects of rejuvenator on

performance-based properties of rejuvenated asphalt binder

and mixtures, Constr. Build. Mater. 21 (5) (2007) 958-964.

[77] P. S. Lin, T. L. Wu, C. W. Chang, B. Y. Chou, Effects of

recycling agents on aged asphalt binders and reclaimed

asphalt concrete, Mater. Struc. 44 (5) (2011) 911-921.

[78] M. Zaumanis, R. B. Mallick, R. Frank, Evaluation of

different recycling agents for restoring aged asphalt binder

and performance of 100% recycled asphalt, Mater. Struc. 48

(8) (2015) 2475-2488.

[79] N. Pratik, C. S. Umesh, A rheological study on aged binder

rejuvenated with Pongamia oil and Composite castor oil,

Inter. J. Pave. Eng. 18 (7) (2015) 595-607.

[80] P. A. Dokandari, D. Kaya, B. Sengoz, A. Topal,

Implementing Waste Oils with Reclaimed Asphalt

Pavement, Proc. 2nd World Congress on Civil, Structural,

and Environmental Engineering (CSEE’17), 2017 2371-

5294.

[81] M. Chen, B. Leng, S. Wu, Y. Sang, Physical, chemical and

rheological properties of waste edible vegetable oil

rejuvenated asphalt binders, Constr. Buil. Mater. 66 (2014)

286–298.

[82] H. Asli, E. Ahmadinia, M. Zargar, M.R. Karim,

Investigation on physical properties of waste cooking oil–

Rejuvenated bitumen binder, Constr. Buil. Mater. 37 (2012)

398–405.

[83] A. Dony, J. Colin, D. Bruneau, I. Drouadaine, J. Navaro,

Reclaimed asphalt concretes with high recycling rates:

changes in reclaimed binder properties according to

rejuvenating agent. Constr. Build. Mater 41 (2013) 175.

[84] Cargill. Rejuvenation of aged bitumen: Increasing RAP and

RAS content while maintaining performance. (2017).

https://www.cargill.com/bioindustrial/anova/asphalt-

rejuvenators, (accessed 15 April 2018).

[85] ArrMaz. Asphalt rejuvenators for Reclaimed Asphalt

Pavements. (2017). https://arrmaz.com/products/road-

science-asphalt-technology/asphalt-additives/asphalt-

rejuvenators-recycled-asphalt-pavement/, (accessed 15 April

2018).

[86] N. H. Tran, A. Taylor, R. Willis, Effect of rejuvenator on

performance properties of HMA mixtures with high RAP

and RAS contents. NCAT Report 12-05, Auburn University,

2012.

[87] W.S. Mogawer, A. Booshehrian, S. Vahidi, A.J. Austerman,

Evaluating the effect of rejuvenators on the degree of

blending and performance of high RAP, RAS, and RAP/RAS

mixtures, Road Mater. Pave. Des. 14 (2013) 193–213.

[88] R. B. Mallick, M. Tao, K. A. O'Sullivan, R. Frank, Use of

100% Reclaimed Asphalt Pavement (RAP) Material in

Asphalt Pavement Construction. In Proceeding of the 89th

Conference of International Society of Asphalt Pavement.

Nagoya, Japan, 2009.

[89] J. F. Su, E. Schlangen, Y. Y. Wang, Investigation the self-

healing mechanism of aged bitumen using microcapsules

containing rejuvenator, Constr. Build. Mater. 85 (2015) 49-

56.

[90] A. S. Noureldin, L. E. Wood, Rejuvenator diffusion in

binder film for hot-mix recycled asphalt pavement, Transp.

Res. Rec. 1115 (1987).

[91] J. Sullivan, Pavement recycling executive summary and

report. FHWA-SA-95-060. Federal Highway

Administration, Washington D.C., U.S.A., 1996.

[92] Indian Roads Congress, Tentative specifications for

bituminous concrete. IRC: 105-1988., New Delhi, India,

1998.

[93] Asphalt Institute, Superpave Mix Design. Superpave Series

No. 2 (SP-02). Asphalt Institute, Lexington, KY., 2001.

[94] R. Izaks, V. Haritonovs, I. Klasa, M. Zaumanis, Hot Mix

Asphalt with High RAP Content. , Proc. Eng. 114 (2015)

676–684.

L. Devulapalli et al. / International Journal of Pavement Research and Technology 12 (2019) 185-196 195

[95] R. S. McDaniel, A. Shah, G. Huber, Investigation of low-

and high-temperature properties of plant-produced RAP

mixtures. No. FHWA-HRT-11-058. West Lafayette, IN,

U.S.A., 2012.

[96] H. R. Paul, Evaluation of recycled projects for performance.

Asph. Paving Tech. 65 (1996) 231-254.

[97] L. Mohammad, M. Y. Abu-Farsakh, Z. Wu, C. Abadie,

Louisiana experience with foamed recycled asphalt

pavement base materials, Transp. Res. Rec.1832 (2003) 17-

24

[98] P. S. Kandhal, F. Parker, R. B. Mallick, Aggregate tests for

hot-mix asphalt: state of the practice. Transp. Res. Brd.

National Research Council. No. 479. Washington D.C.,

U.S.A., 1997.

[99] S. Zaghloul, T. Holland, Comparative analysis of long-term

field performance of recycled asphalt in California

environmental zones, Transp. Res. Rec. 2084 (2008) 83-99.

[100] R. West, A. Kvasnak, N. Tran, B. Powell, P. Turner, Testing

of moderate and high reclaimed asphalt pavement content

mixes: laboratory and accelerated field performance testing

at the national center for asphalt technology test track,

Transp. Res. Rec. 2126 (2009) 100-108.

[101] T. B. J. Coenen, A. GolrooA review on automated pavement

distress detection methods, Cogent Eng. 4 (1) (2017).

[102] A. Stimilli, A. Virgili, F. Giuliani, F. Canestrari, Mix design

validation through performance-related analysis of in plant

asphalt mixtures containing high RAP content, Inter. J. Pave.

Res. Tech. 10 (1) (2017) 23-37.

[103] T. A. Pradyumna, P. K. Jain, Use of RAP Stabilized by Hot

Mix Recycling Agents in Bituminous Road Construction,

Transp. Res. Proc. 17 (2016) 460-467.

[104] A. Hussain, Q. Yanjun, Effect of Reclaimed Asphalt

Pavement on the properties of asphalt binders, Proc. Eng. 54

(2013) 840–850.

[105] K. Aravind, A. Das, Pavement design with central plant hot-

mix recycled asphalt mixes, Constr. Build. Mater. 21 (5),

(2007) 928–936.

[106] C. Yan, W. Huang, Q. Lv, Study on bond properties between

RAP aggregates and virgin asphalt using Binder Bond

Strength test and Fourier Transform Infrared spectroscopy,

Constr. Build. Mater. 124 (2016) 1-10.

[107] S. Im, F. Zhou, R. Lee, T. Scullion, Impacts of rejuvenators

on performance and engineering properties of asphalt

mixtures containing recycled materials, Constr. Build.

Mater. 53 (2014) 596-603.

[108] O. Reyes-Ortiz, E. Berardinelli, a. E. Alvarez, J. S. Carvajal-

Muñoz, L. G. Fuentes, Evaluation of Hot Mix Asphalt

Mixtures with Replacement of Aggregates by Reclaimed

Asphalt Pavement (RAP) Material. Procedia - Social and

Behavioral Sciences, 53 (2012) 379–388.

[109] S. Coffey, E. DuBois, Y. Mehta, A. Nolan, C. Purdy,

Determining the impact of degree of blending and quality of

reclaimed asphalt pavement on predicted pavement

performance using pavement ME design, Constr. Build.

Mater. 48 (2013) 473–478.

[110] R. Ghabchi, D. Singh, M. Zaman, Evaluation of moisture

susceptibility of asphalt mixes containing RAP and different

types of aggregates and asphalt binders using the surface free

energy method, Constr. Build. Mater. 73 (2014) 479–489.

[111] P. Sebaaly, G. Bazi, E. Hitti, D. Weitzel, S. Bemanian,

(2004). Performance of cold in-place recycling in Nevada,

Transp. Res. Rec. 1896 162-169.

[112] L.D. Poulikakos, S. dos Santos, M. Bueno, S. Kuentzel, M.

Hugener, M.N. Partl, Influence of short and long-term aging

on chemical, microstructural and macro-mechanical

properties of recycled asphalt mixtures, Constr. Build.

Mater. 51 (2014) 414–423.

[113] A. Behroozikhah, S.H. Morafa, S. Aflaki, Investigation of

fatigue cracks on RAP mixtures containing Sasobit and

crumb rubber based on fracture energy, Constr. Build. Mater.

141 (2017) 526–532.

[114] J. Jiang, F. Ni, J. Zheng, Y. Han, X. Zhao, Improving the

high-temperature performance of cold recycled mixtures by

polymer-modified asphalt emulsion, Inter. J. Pave. Eng.

(2018) 1-8.

[115] C. Giavarini, “Polymer-modified bitumen.” Developments

in Petroleum Science, Elsevier. 40 (1994) 381-400.

[116] Z. Zhou, X. Gu, F. Ni, Y. Jiang, Cracking Performance of

Laboratory-Produced Polymer Modified Asphalt Mixture

Containing Reclaimed Asphalt Pavement Material: a

Multiscale Analysis. No. 18-02599. Washington D.C.,

U.S.A., 2018.

[117] S. Kim, G. A. Sholar, T. Byron, J. Kim, Performance of

polymer-modified asphalt mixture with reclaimed asphalt

pavement, Transp. Res. Rec. 2126 (1) (2009) 109-114.

[118] F. Xiao, S. N. Amirkhanian, J. Shen, B. Putman, Influences

of crumb rubber size and type on reclaimed asphalt pavement

(RAP) mixtures, Constr. Build. Mater. 23 (2) (2009)1028-

1034.

[119] D. Singh, D. Sawant, F. Xiao, High and intermediate

temperature performance evaluation of crumb rubber

modified binders with RAP. Transportation Geotechnics, 10

(2017) 13-21.

[120] A. Bernier, A. Zofka, I. Yut, Laboratory evaluation of

rutting susceptibility of polymer-modified asphalt mixtures

containing recycled pavements, Constr. Build. Mater. 31

(2012) 58-66.

[121] D. Singh, D. Sawant, Understanding effects of RAP on

rheological performance and chemical composition of SBS

modified binder using series of laboratory tests, Inter. J.

Pave. Res. Tech. 9 (3) (2016) 178-189.

[122] J. Shen, S. Amirkhanian, S. J. Lee, B. Putman, Recycling of

Laboratory-Prepared Reclaimed Asphalt Pavement Mixtures

Containing Crumb Rubber–Modified Binders in Hot-Mix

Asphalt, Transp. Res. Rec. 1962 (1) (2006) 71-78.

[123] D. Singh, Girimath, S. Influence of RAP sources and

proportions on fracture and low temperature cracking

performance of polymer modified binder, Constr. Build.

Mater. 120 (2016) 10-18.

[124] M. Zaman, M. Z. Rahaman, Z. Hossain, Nonrecoverable

Compliance and Recovery Behavior of Polymer-Modified

and Reclaimed Asphalt Pavement (RAP)–Modified Binders

in Arkansas, J. Test. Eval. 46 (6) (2018).

[125] N. Lee, C. P. Chou, K. Y. Chen, Benefits in energy savings

and CO2 reduction by using reclaimed asphalt pavement, In

Transportation Research Board 91st annual meeting, 2012.

[126] Q. Aurangzeb, I.L. Al-Qadi, H. Ozer, R. Yang, Hybrid life

cycle assessment for asphalt mixtures with high RAP

content. Resources, Conserv. Recycling 83 (2014) 77–86.

[127] M. Waymen, Y. Andersson-skold, R. Bergmen, Y. Huang,

T. Parry, J. Raaberg, Life cycle assessment of Reclaimed

Asphalt Pavement. European Commission, 2012.

[128] A. Farina, M.C. Zanetti, E. Santagata, G.A. Blengini, Life

cycle assessment applied to bituminous mixtures containing

196 L. Devulapalli et al. / International Journal of Pavement Research and Technology 12 (2019) 185-196

recycled materials: Crumb rubber and reclaimed asphalt

pavement. Resources, Conserv. Recycling 117 (2017) 204–

212.

[129] A. Jamshidi, M.O. Hamzah, Z. Shahadan, Selection of

Reclaimed Asphalt Pavement sources and contents for

asphalt mix production based on asphalt binder rheological

properties, fuel requirements and greenhouse gas emissions,

J. Cleaner Prod. 23 (1) (2012) 20-27.

[130] H. M. Silva, J. R. Oliveira, C. M. Jesus, Are totally recycled

hot mix asphalts a sustainable alternative for road paving?

Resources, Conserv. Recycling 60 (2012) 38-48.

[131] R. Vidal, E. Moliner, G. Martínez, M. C. Rubio, Life cycle

assessment of hot mix asphalt and zeolite-based warm mix

asphalt with reclaimed asphalt pavement, Resources,

Conserv. Recycling 74 (2013) 101-114.