Recycling of different plastics in asphalt concrete

The benefits and environmental implications of utilizing various recycled plastic waste (PW) in asphalt concrete (AC) is studied. The emission estimates and the performance of PW-modified binders in addition to selected PW-modified asphalt concrete mixtures is evaluated and compared to conventional modified and unmodified asphalts. Results show that adopting the PW-modified asphalt has the potential of eliminating huge amounts of carbon emission along with nonmethane volatile organic compounds (NMVOCs) from atmosphere annually. Moreover, a significant improvement in viscoelastic properties and performance grading of the asphalt binder modified with the PW and in combination of virgin polymers is observed. Most of the PW-modified AC mixtures show higher values of resilient modulus (Mr), indirect tensile strength (ITS), and retained strength index (RSI) than those for the conventional ACs that contain polybilt (PB), styrene-butadiene-styrene (SBS), or crumb rubber (CR), indicating better performance in terms of crack resistance and moisture sensitivity. The various PW asphalts show distinct thermal susceptibility, which confirms the feasibility of combining different PWs for much better thermal properties. The pure PW-modified asphalt binders result in negligible CO2 and NMVOC emissions. Combination of the PW with the conventional polymers also shows significantly lower CO2 and NMVOC emissions than when the virgin polymers are employed.