Preparing hybrid-treated plastic particles from waste plastic includes combining waste plastic particles with bio-oil to yield a mixture, irradiating the mixture with microwave radiation to yield oil-treated plastic particles, and contacting the oil-treated plastic particles with carbon-containing nanoparticles to yield hybrid-treated plastic particles. The hybrid-treated plastic particles have a bio-oil modified surface and a coating comprising carbon-containing nanoparticles on the bio-oil modified surface of the plastic particle. In some examples, a diameter of the plastic particle is in a range between 250 m and 750 m, and a thickness of the coating is in a range of 1 nm to 20 nm. A modified binder includes an asphalt binder or a concrete binder and a multiplicity of the treated plastic particles. The modified binder typically includes 5 wt % to 25 wt % of the hybrid-treated plastic particles.