Effect of recycled agricultural waste on fume emission and physicochemical properties of crumb rubber modified asphalt

Abstract

Crumb rubber modified asphalt (CRMA) in the application process often produces lots of toxic fumes, and the composition is dominated by total volatile organic compounds (TVOCs) and H2S, which restricts its large-scale use in practical engineering. Therefore, three preferred agricultural wastes namely wood chip powder (WCP), peanut shell flour (PSF) and moxa stick ash (MSA) were added to CRMA to investigate their inhibition effect on CRMA fume in this work, and their inhibition mechanism on CRMA fume emission was discussed. Meanwhile, the influence effect of added agricultural waste on the physicochemical properties of CRMA was further analyzed and the modification mechanism was also explored. The experimental results indicate that the incorporated WCP, PSF and MSA can all inhibit the emission of TVOCs and H2S in CRMA to varying degrees. Compared with CRMA, the TVOCs concentrations of CRMA-WCP, CRMA-PSF and CRMA-MSA are reduced by 36.87 %, 11.72 % and 46.22 % under 190°C, respectively, while the H2S concentrations can be reduced by 53.45 %, 5.03 % and 62.67 %, respectively. The three agricultural wastes contain different mesoporous structures and their inhibition of CRMA fume is dominated by physical adsorption. Moreover, the added WCP, PSF and MSA can also synergize with crumb rubber to strengthen the rutting resistance of asphalt and upgrade the elastic recovery capacity of asphalt under different loads, and the enhancement effect is in the order of WCP > PSF > MSA. In summary, the three agricultural wastes preferred in this research are effective in suppressing the emission of toxic fumes from CRMA while improving its working performance, which can provide a new avenue for fume suppression in CRMA and multi-channel utilization of agricultural waste.