Using recycled plastic waste to improve the performance of hot-mix asphalt

The use of recycled plastics in asphalt mixtures has become a major interest for the pavement and plastics industries due to the potential environmental benefits. An investigation was carried out into the use of three recycled plastic waste materials to modify asphalt binders and influence the performance of the resulting hot-mix asphalt. Asphalt binders were modified with three different types of recycled plastics: high-density polyethylene, low-density polyethylene and polypropylene. Marshall stability and flow were determined for 12 control mixtures using unmodified binders and 72 mixtures modified by different percentages of recycled plastic. Results revealed that, in general, recycled plastic enhanced the stability of hot-mix asphalt. Both recycled high-density polyethylene and polypropylene resulted in higher mixture stability than low-density polyethylene. Optimum stability for all recycled plastic types was achieved at 8% plastic content by weight of asphalt. Mixes with 8% high-density polyethylene increased stability over the unmodified mixture by almost 17% and reduced flow by 7%. This type of plastic waste also had the highest Marshal quotient value, which suggests a better performance than the other two.