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The XXVIII International Baltic Road Conference
USE OF REJUVENATORS FOR PRODUCTION OF SUSTAINABLE HIGH
CONTENT RAP HOT MIX ASPHALT
Martins Zaumanis1, Rajib B. Mallick2, Robert Frank3
1,2Worcester Polytechnic Institute (WPI), Worcester, MA, United States
3Compliance Monitoring & RAP Technologies, Linwood, NJ, United States
1100 Institute Road, Kaven Hall, Worcester, MA 01609, firstname.lastname@example.org
2100 Institute Road, Kaven Hall, Worcester, MA 01609, email@example.com
3217 Belhaven Avenue, Linwood, NJ 08221, firstname.lastname@example.org
Abstract. Aged binder is the main obstacle for increasing the use or Reclaimed Asphalt Pavement (RAP) in production of asphalt
pavements. RAP binder is much stiffer and therefore high RAP content mixes are perceived to be susceptible to fatigue and thermal
cracking failures. Appropriate choice of rejuvenator may allow reducing the binder viscosity to attain the desired mixture workability
and recover the necessary performance properties of the aged binder. Six differently originated rejuvenators were added to extracted
binder at 12% dose including aromatic extract, waste engine oil, tall oil, organic oil, waste vegetable oil and waste vegetable grease.
The rejuvenation potential of these products was evaluated by performing multiple empirical as well as performance tests and the
results compared with a virgin binder. The rejuvenators proved to soften the extracted binder to the level of virgin and the kinematic
viscosity results show that the optimum compaction temperature can be reduced by 15°C to 25°C compared to extracted binder.
Performance Grade (PG) test results showed that none of the rejuvenators reduced the high PG of extracted binder to the level of
virgin binder indicating increased rutting resistance. At the same time most are able to reduce low PG from -12°C of the extracted
binder to at least the required -22°C. The low temperature performance correlated well with penetration index, proving that thermal
cracking should not be an issue at appropriate rejuvenator dose. The binder fatigue performance was evaluated through Linear
Amplitude Sweep (LAS) test. Only waste vegetable products were able to increase the fatigue resistance to the level of virgin binder
at a 12% dose using LAS test while the Superpave G*·sinδ indicated that all rejuvenators pass the minimum fatigue requirement.
Keywords. Rejuvenators, softening agents, waste vegetable oil, linear amplitude sweep test.
Reclaimed Asphalt Pavement (RAP) binder properties depend on the composition of the original
binder and aging during service. If the aggregates are of good quality, then the main obstacle for
increasing the RAP dosage, is the aged RAP binder. The stiff binder has low workability and may
cause fatigue and thermal cracking.
A successful use of rejuvenators should reverse the RAP binder aging process, restore the properties
of asphalt binder for another service period and make the RAP asphalt effectively “available” to the
mix, and hence allow a significant increase in the amount of RAP that could be used in Hot Mix
Asphalt (HMA). However, it is necessary to carefully select the rejuvenator to provide the
necessary short and long term properties, as follows.
1. Short term. Rejuvenators should allow the production of high RAP content mixture by rapidly
diffusing into the RAP binder and mobilizing the aged asphalt in order to produce uniformly
coated mixtures. Rejuvenator should soften the binder in order to produce a workable mixture
that can be easily paved and compacted to the required density without the hazard of
producing harmful emissions. Major part of diffusion process should be completed before the
traffic is allowed to avoid reduction of friction and increased susceptibility to rutting.
2. Long term. Rejuvenators should reconstitute chemical and physical properties of the aged
binder and maintain stability for another service period. The binder rheology has to be altered
to reduce fatigue and low temperature cracking potential without over softening the binder to
cause rutting problems. Sufficient adhesion and cohesion have to be provided in the mix to
prevent moisture damage and raveling.
1 RESEARCH APPROACH AND MATERIALS
The objective of the research is to evaluate the use of rejuvenators for restoring the desirable
properties of the aged RAP binder in order to produce very high content RAP hot mix asphalt.
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Fig 1. Research Test Plan
1.2 Test plan and Methods
The test methods used in this study for binder evaluation are summarized in Figure 1. Mixing of
rejuvenators with the extracted binder demonstrates the effects of 100% blending; the penetration
and viscosity tests were carried on unaged samples, but the blended samples for performance
grading (PG) were aged according to standard procedure for virgin binders.
The binder was extracted from the RAP using toluene according to ASTM 2172, method A and
recovered using rotary evaporator, according to ASTM D5404. Typically a PG 64-22 binder is used
in this climatic area and therefore this grade was selected as a reference binder.
Six different rejuvenating agents are used in the study. The products have been labeled by generic
descriptors that briefly define the origins of the products. Measured kinematic viscosity and the
specific gravity along with the some basic characteristics obtained from manufacturers are included
in Table 1. The rejuvenator dose selection (12% from binder mass) is based on the author’s
previous study (Zaumanis et al., 2013) as a compromise between all of the rejuvenators. The
research results suggested that this is close to optimum dose for organic products, but lower than
that required for petroleum products.
Table 1. Rejuvenator properties and description
structure Polarity Traditional
Nustar PG 64-22 474 1.02 Generic Petroleum Refined Ring and Strand Mixed Traditional
Aromatic Extract 9.20 0.995 Generic Petroleum Refined Aromatic Ring Very Traditional
Waste Engine Oil 3.86 0.872 Generic Petroleum Waste Aliphatic Slight Traditional
Distilled Tall Oil 5.60 0.950 Generic Organic Refined Ring and Strand Mild Traditional
WV Grease 4.28 0.924 Generic Organic Waste Ring and Strand Mild Novel
WV Oil 5.17 0.917 Generic Organic Waste Ring and Strand Non Novel
Organic Oil 5.43 0.947 Engineered Organic Refined Ring and Strand Mild Traditional
The XXVIII International Baltic Road Conference 3
1.4.1 Aromatic extract
An aromatic extract is a traditional rejuvenator with dominant polar aromatic rings. Recent findings
show concern with unsaturated polar aromatic ring structure, which have been shown to be
carcinogenic (The Petroleum HPV Testing Group, 2012). This research is not intended to promote
the use of aromatic extract, but rather to allow comparing other products to a rejuvenator, that has
been used historically and has demonstrated acceptable results. Aromatic extracts contain
approximately 75% polar aromatic oils, resin compounds with balance less polar aromatics.
Proponents claim polar aromatics associate with asphaltene molecules and in the process make
binder less brittle, by balancing the chemistry of the oxidized aged binder.
1.4.2 Waste Engine Oil (WEO)
WEO is produced from paraffinic oil with small dose of specialty compounds to improve viscosity
characteristics, stability, cleaning and flammability for use in engines. WEO may contain short
chain polar molecules that break apart during lubricating service. Recent interest in waste engine oil
re-refineries around the world is making WEO increasingly difficult to obtain and more costly.
1.4.3 Refined tall oil
SylvatalTM D30E tall oil is produced by Arizona Chemical. It is a byproduct of paper manufacture
being concentrated from kraft liquors. Tall oil is available either in crude form or as refined
products. Crude tall oil contains fatty acids, resin acids and unsaponifiables in varying ratios
depending on tree type used. Tall oils have a long history of use in hot mix manufacture with many
emulsifiers, antistrip agents and warm mix additives.
1.4.4 Waste Vegetable Oil (WV Oil)
WV Oil is increasingly used for bio-diesel production and has very strict compositional
specifications including low free fatty acid content (<15%), less than 2% MIU (Moisture,
Impurities, Unsaponifiables) (National Renderers Association, 2008). Derived from fast and
convenience food frying oil, it is also referred as “yellow grease”. The product used in this study
consists predominately of peanut, sunflower, and canola oils, with large concentrations of Oleic and
1.4.5 Waste Vegetable Grease (WV Grease)
WV Grease is also a food industry organic waste stream but semi solid at ambient temperatures due
to predominance of saturated Lauric and Myristic triglcerides. The product used in study is also
high in free fatty acids (>40%) but with its free glycerin and moisture removed industrially.
1.4.6 Organic oil
Hydrogreen STM is an engineered product by PVS Meridian Technologies, Inc and is designed to be
binder rejuvenator and a low temperature additive. It is composed of fast pyrolysis of pine tree
biomass (Harshavardhan et al., 2012) with other oils added to balance performance. The product is
free flowing most of the year, but slight heating to around 10°C is necessary when used in cold
2 PERFORMANCE GRADE
The extracted RAP binder was tested for Performance Grade (PG) after addition of each of the
rejuvenators and the results, along with the virgin binder PG 64-22, are illustrated in Figure 2. They
show that RAP binder has aged significantly and grades as PG 94-12. The addition of all products
allowed reducing both the high and low binder grade compared to the extracted binder suggesting
not only decrease in viscosity but also increasing in elasticity. None of the products was quite able
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to reduce the high grade to the level of virgin binder indicating lower susceptibility to rutting. This
shows that, despite the general concern, if adequate dose of rejuvenator is used and good diffusion
occurs in asphalt binder film, there is no danger of increased rutting susceptibility with the use of
rejuvenators. Note that this assumes that there is 100% diffusion of the rejuvenators in the binder.
The required low performance grade (-22°C) was reached in all cases except when using WEO.
Most of the products are actually able to reduce the PG much lower than required, and at the dose of
12%, organic oil and WV oil have provided the lowest cracking temperature.
Penetration Index (PI) was developed to describe the temperature susceptibility of binder. However,
Burke et.al (Burke et al., 2011) in their research on field performance of binder that has been
modified with re-refined waste engine oil residue suggested the use of PI of binder in respect to its
expected thermal and fatigue cracking performance. Their research proposes PI as a good measure
of steric hardening (asphaltene structure formulation over time) that promotes accelerated oxidative
hardening and gel-type structure that retain higher stress levels at low temperatures. According to
their research an increase in PI, despite sufficient low temperature performance grade, indicates low
temperature cracking susceptibility.
PI was calculated from penetration results at temperatures of 10°C and 25°C according to Equations
1 and 2, developed by Pfeiffer and Van Doormaal (Whiteoak et al., 2003). Figure 3 shows good
correlation of rejuvenated binder PG and PI, confirming that low temperature performance has been
in fact improved. The virgin PG 64-22 likely has a different origin and therefore its PI is
significantly different from rejuvenated binders.