Synthesis and characterization of biomodified rubber asphalt: Sustainable waste management solution for scrap tire and swine manure

This paper investigates the feasibility of the application of scrap tire and swine manure to produce a sustainable alternative for bituminous asphalt used in pavement construction. Biobinder is produced from swine manure by using a thermochemical conversion process; biobinder is then blended with crumb rubber and asphalt binder (PG 64-22) to produce biomodified rubber (BMR) asphalt. In addition to offering a renewable alternative for petroleum-based binder, BMR can be a hybrid environmental solution for the management of swine manure and scrap tire. To study the merit of application of BMR in the asphalt industry, this paper compares the rheological properties of BMR with a crumb rubber-modified (CRM) binder commonly being used in the United States. The authors found that BMR has comparable properties with the CRM binder. In addition, the authors found that the introduction of the biobinder to the CRM binder was beneficial in improving the low temperature property of the CRM binder while also reducing the CRM binder's overall viscosity. In turn, this would allow for lower mixing and compaction temperatures of CRM asphalt while alleviating crumb rubber's stiffening effect and enhancing the CRM asphalt's pumpability. A lower mixing and compaction temperature will reduce the greenhouse gas emission during application of the CRM binder in pavement construction.