Factors Affecting the Properties of PCB-Modified Asphalt

Abstract

Waste tire pyrolysis has the advantages of economy, environmental protection, and high energy conversion rate; however, there is little research on the application of pyrolysis carbon black (PCB), which accounts for a high percentage of pyrolysis products, in asphalt and asphalt mixtures. The objectives of this study were to investigate the effect of PCB ash on the physical properties of asphalt binders, the effect of coupling treatment on the dispersibility of PCB-modified asphalt, and the effect of mixing process on the road properties of PCB asphalt mixtures. The physical properties of co-pyrolytic carbon black (CPCB) and low-temperature vacuum pyrolytic carbon black (VPCB) blended with 70# base asphalt and styrene-butadiene-styrene (SBS)–modified asphalt (SBSMA) were evaluated. Mechanisms behind the differences in the dispersion of CPCB in asphalt were revealed. In addition, the road performance of different PCB asphalt mixtures was compared. The results indicate that the optimum admixtures of VPCB and CPCB in 70# base asphalt are recommended to be 20% and 10%–15%, respectively, and the optimum admixtures of VPCB and CPCB in SBSMA are 10%–25% and 10%–20%, respectively. Acid washing reduces the ash content of the CPCB surface, and coupling agent can promote the dispersion of CPCB in asphalt. The wet-prepared CPCB-modified asphalt mixtures showed overall better road performance than the dry-prepared ones. Dry CPCB asphalt mixtures with 50% cement instead of equal mass of mineral powder have the potential to replace the wet process.