Use of microbially desulfurized rubber to produce sustainable rubberized bitumen

Sk Faisal Kabir, Renfei Zheng, Anca G. Delgado, Elham H. Fini

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

This paper examines the merits of using microbially desulfurized rubber to enhance theperformance ofbituminous pavements and promote recycling of scrap tires. To prepare microbially desulfurized rubber, we incubated crumb rubber obtained from waste tiresin medium with microbes from waste activated sludge. The concentration of sulfate was monitored during the treatment process and desulfurization was estimated to be about34%.Microbially desulfurized crumb rubber (MDR) was then added to bitumen to produce rubberized bitumen. Performance of the rubberized bitumen was compared with those of conventional crumb rubber modified (CRM) bitumen. To do so, Fourier transform infrared spectroscopy (FTIR), inverse gas chromatography (IGC), and rheometry were utilized. Chemical analysis of rubber particles after desulfurization showed a significant reduction of the peak at 500-540 cm−1; this was attributed to the breakage of disulfide bonds after microbial desulfurization. Measurement of surface energy showed that the acid-base component of surface energy increased three times (increasing from 1.85mJ/m2 to 5.55mJ/m2) after desulfurization. Such enhancement could lead to increased interactions between rubber and bitumen reducing their separation. This was evidenced ina68% reduction inseparation indexin bitumencontaining microbially-treated (desulfurized) rubber compared to bitumen havingnon-treated rubber. In addition, study results showed a 6% increase in elastic recovery,a 27% increase in resistance to moisture diffusion,a 12.5% decrease in viscosity,a 10% increase in stiffness, and a 5% increase in stress relaxation capacity compared to bitumen's having non-treated rubber. The outcome of the study promotes resource conservation by offering a simultaneous solution for recycling of scrap tire via a low-cost bio-inspired approach while enhancing pavement performance.

Original languageEnglish (US)
Article number105144
JournalResources, Conservation and Recycling
Volume164
DOIs
StatePublished - Jan 2021

Keywords

  • Activated sludge
  • Bitumen
  • Crumb rubber
  • Microbial desulfurizing
  • Segregation

ASJC Scopus subject areas

  • Waste Management and Disposal
  • Economics and Econometrics

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