Abstracts Book - IMRC 2018

• SF5-O035
THE FATIGUE RESISTANCE OF RAP IN ASPHALT CONCRETE MIXES
USING TWO DIFFERENT BINDERS
Dale Diaz 1 , Trevor Townsend 1 , Lee Leon 1
1 The University of the West Indies, St. Augustine, Civil & Environmental Engineering, Trinidad
and Tobago.
Fatigue cracks in asphalt concrete are recognized as one of the most major
distress mechanism in asphalt pavements. This type of deterioration must be
understood and the causes of the distress must be identified. The objective of
this study was aimed at evaluating the fatigue resistance of stone matrix asphalt
(SMA) concrete mixtures using laboratory testing techniques. The SMA mixes
were designed with different percentages of Reclaimed Asphalt Pavement (RAP)
as well as virgin aggregates. Two binders 60/70 - Modified Bitumen (MB) and
60/75 - Trinidad Lake Asphalt (TLA) were used. The fatigue resistance of the
asphalt concrete mix was evaluated using three performance tests which
included Stiffness Modulus, Indirect Tensile Fatigue and Static Creep
Deformation Tests. The laboratory tests showed that with increased RAP
percentages there was a significant improvement in the Stiffness Modulus (SM)
values and the virgin control mix with no RAP was out performed for both TLA
and Modified Bitumen (MB). The peak SM was observed at the inclusion of 50%
RAP. The results for the Indirect Tensile Fatigue Test (ITFT) showed the MB mixes
of 5% RAP had the highest resistance to fatigue whereas the TLA mixes of 5%
RAP showed the lowest resistance to fatigue. The mix of MB with 5% RAP
performed significantly better than all other mixes. However, as RAP
percentages increased during the Creep Strain Test the mixtures showed
excellent deformation resistance and the MB outperformed the TLA samples for
40% and 50% RAP increase, showing that modified bitumen has a stronger
deformation resistance. This study revealed that with the increase in RAP
percentages in the two mixes resulted in an improvement in all mechanical
properties especially in the mix containing 50% RAP, which displayed improved
stiffness and creep strain resistance relative to the mixes with other RAP
percentages and the virgin control mix. Also it was found that the mix containing
5% RAP showed high fatigue resistance when compared to the other RAP
percentages and virgin control mix.
Keywords: Fatigue Resistance, Stiffness, Stone Matrix Asphalt
Presenting authors email: dale.diaz@gmail.com