to characterize the properties of RAP-recovered asphalt binder that has been blended with waste engine oil.
RESULTS
INTRODUCTION
In the United States, there are an estimated 250 million registered vehicles traveling on four million miles of
public roads. With such a large volume of traffic, two key waste products are generated: engine oil from the
traffic and asphalt pavement material from old roads. Although the use of recycled asphalt pavements (RAP)
is greatly documented, the use of RAP without modification is known to produce an overall stiffer blend. With
the addition of waste engine oil, this increased stiffness can be offset in order to produce a pavement with a
consistent performance grade.
RESEARCH OBJECTIVE
Dynamic Shear Rheometer (DSR):
Figure 1. shows the results from the DSR testing conducted.
The dashed horizontal line represents the minimum expected
failure value of 1.00 kPa. The addition of 25% RAP increased
the overall binder stiffness. With the increase in the amount
of oil, there was a decrease in the G*/Sin(δ) parameter, which
translates directly to the decrease in maximum temperature
performance grade.
Figure 1: DSR Results
Rotational Viscometer:
Averaged data from the viscometer experiments can
be found in figure 3.When additional oil was added to
the mixture, the binder became softer, as one could
expect a softening agent to do. Thus, there was a
progressive decrease in viscosity with increased
amounts of oil.
Characterize the properties aged asphalt binder that has been blended with waste engine oil.
MATERIALS
A PG 70-22 virgin Asphalt binder was combined with RAP-recovered binder at the ratio of 75% neat binder to 25%
RAP-recovered binder. The RAP-recovered binder was extracted from a RAP stockpile in Hancock, Michigan. The
used engine oil was supplied by the Michigan Tech motor pool. The oil was a Chevron Delo 400 LE SAE 15W30
Diesel type oil.
Figure 2: Rotational Viscometer Results
The oil was blended with the RAP blend in two concentrations; 4 and 8% by weight of total mix. With the aid of a
glass rod and under continuous stirring action, the binders were mixed homogenously in a standard specimen can
over a hot plate at temperatures around 150 ⁰C.
RECOMENDATIONS
Dynamic Shear Rheometer (DSR)
It is important to note this is a preliminary
study. In order to completely investigate the
feasibility of using waste engine oil in asphalt
pavements, more research should be
conducted on different percentages of RAP
binder. Additionally, an extensive range of
other tests will be conducted to further
assess the feasibility of using engine oils in
the asphalt pavements.
TESTING
Two types of tests were conducted on the prepared asphalt blends. Using a Brookfield model DV-II Viscometer, the
viscosities of the binders were tested to quantify the amount of softening undergone with increasing oil.
The other type of test conducted was Rheometer testing using a Bolhin CVO 120 DSR. The DSR measures the Complex
Modulus (G*) and phase angle (δ) of each sample. The Superpave system uses the parameter G*/Sin (δ) as an
indication of the rutting or permanent deformation standard performance criterion. When this parameter is greater
than 1.00 kPa for unaged asphalt at a given temperature, the binder meets that the rutting criterion for performance
and is then progressively tested at higher temperatures until it fails.
For both DSR and Rotational Viscometer test
results, the asphalt became softer as
increasing amounts of waste engine oil was
added. The percentage of oil shows a direct
relationship with decreased stiffness.
Rotational Viscometer