Mechanism behind Time Dependent Elasticity of Crumb Rubber-Nano-Asphalt Hybrids Using Discrete Relaxation Spectrum

Abstract

Crumb rubber powder is a successfully used renewable material obtained from waste tire rubber, which has been incorporated into paving asphalt since the 1930s due to its good resistance to deformation and fatigue as well as its eco-friendly performance. In this study, carbon nanotubes and nano silica were incorporated into the terminal blend crumb rubber modified asphalt technology to remedy the issues of excessive desulfurization and degradation of ground tyre rubber with this technology. The mechanism behind the high temperature delayed elastic properties of the crumb rubber-nano-asphalt hybrids was experimentally investigated based on discrete relaxation spectrum. Development of the discrete relaxation spectra was accomplished by fitting on the 60°C storage modulus data tested by the dynamic shear rheometer using the generalized Maxwell model. Subsequently, the feasibility of characterizing delayed asphalt elasticity using main relaxation time was verified by test results from the 60°C creep and recovery test. Results indicated that the crumb rubber-nano-asphalt hybrids exhibited arrheodictic behavior and the asphalt elasticity was strengthened by two nano agents. Moreover, the elasticity reinforcement with carbon nanotubes was greater than with nano silica. Additionally, a good correlation was observed between the 60°C zero shear viscosity and main relaxation time, and greater 60°C zero shear viscosity was correlated to longer main relaxation times. Furthermore, longer main relaxation time of the asphalt was related to greater average recovery rate in the creep and recovery test. This research is expected to shed some light on the mechanism behind time-dependent elasticity of crumb rubber modified asphalt from the perspective of polymer physics.

Evaluation and Correlation Analysis of the Rheological Properties of Ground Tire Rubber and Styrene Butadiene Styrene Compound-Modified Asphalt

“…Researchers have proposed the modification of asphalt by combining inorganic materials such as carbon nanotubes [ 6 ], nano-SiO 2 [ 7 ], graphene nanoplatelets [ 8 ], rice-husk ash [ 9 ], diatomite [ 10 ], and recycled glass powder [ 11 ] with GTR. Adding carbon nanotubes and nano-SiO 2 into GTR-modified asphalt can enhance the elasticity and improve the resistance of the asphalt to creep [ 6 , 7 ]. In addition, nano-SiO 2 can hinder UV radiation and enhance the resistance of the asphalt to UV aging [ 7 ].…”

“…Therefore, compounding GTR and other materials to modify asphalt is also gradually being emphasized. Researchers have proposed the modification of asphalt by combining inorga terials such as carbon nanotubes [6], nano-SiO2 [7], graphene nanoplatelets [8], r ash [9], diatomite [10], and recycled glass powder [11] with GTR. Adding carbo tubes and nano-SiO2 into GTR-modified asphalt can enhance the elasticity and the resistance of the asphalt to creep [6,7].…”

“…[18] emphasized that GTR and SBS-modified asphalt not only have excellent tional properties, but also the interface bonding between the compound-modified and the aggregate is superior to that of SBS-modified asphalt. Liu et al [19] analy effect of low-content GTR on the properties of SBS-modified asphalt, and the stud pointed out that the plasticity of GTR and SBS-modified asphalt increased with tion in GTR content (from 2% to 6%), and the softening point and elastic recov Researchers have proposed the modification of asphalt by combining inorganic materials such as carbon nanotubes [6], nano-SiO 2 [7], graphene nanoplatelets [8], rice-husk ash [9], diatomite [10], and recycled glass powder [11] with GTR. Adding carbon nanotubes and nano-SiO 2 into GTR-modified asphalt can enhance the elasticity and improve the resistance of the asphalt to creep [6,7].…”

“…Liu et al [19] analy effect of low-content GTR on the properties of SBS-modified asphalt, and the stud pointed out that the plasticity of GTR and SBS-modified asphalt increased with tion in GTR content (from 2% to 6%), and the softening point and elastic recov Researchers have proposed the modification of asphalt by combining inorganic materials such as carbon nanotubes [6], nano-SiO 2 [7], graphene nanoplatelets [8], rice-husk ash [9], diatomite [10], and recycled glass powder [11] with GTR. Adding carbon nanotubes and nano-SiO 2 into GTR-modified asphalt can enhance the elasticity and improve the resistance of the asphalt to creep [6,7]. In addition, nano-SiO 2 can hinder UV radiation and enhance the resistance of the asphalt to UV aging [7].…”