UTILIZATION OF POLYPROPYLENE TO SUBSTITUTE BITUMEN FOR ASPHALT CONCRETE WEARING COURSE (AC-WC)
Keywords:Asphalt, Bitumen, Polypropylene, Recycling, Plastic waste
In this study, Polypropylene (PP) plastics waste with various concentrations of 0.5%, 0.8%, and
1% were investigated to substitute bitumen’s mass. The mixing of plastics and asphalt was conducted by wet
method, which added PP plastic into the asphalt when being heated so it produced a homogeneous mixture.
Then, AC-WC mixture was made with bitumen contents of 5%, 5.5%, 6%, 6.5%, and 7%. Each mixture was
carried out in triplicate for every plastic’s concentrations. Five parameters of mixtures were tested by Marshall
Method, as follows: VIM, VMA, VFA, stability, and flow. Then, all the parameters were plotted in bar chart
to determine an OBC (optimum bitumen content). Changes in rheological properties after the addition of PP
plastics occurs which indicates the increasing of viscosity, softening point, flash point, and the decreasing of
density, penetration and solubility. Based on Marshall Test, the OBC for asphalt pen 60/70 was 5.4% while the
OBC with PP plastic content of 0.5%, 0.8% and 1%, consecutively, were 5.41%, 5.43% and 5.45%. Despite
the increasing of OBC, this substitution of bitumen to plastics has some advantages such as increasing stability
and remaining strength index (RSI), reducing plastic waste generation and asphalt cost. However, it has
disadvantages such as it consumes more energy and it increases gas emission.