Low-Temperature Rheological Properties and Microscopic Characterization of Asphalt Rubbers Containing Heterogeneous Crumb Rubbers.

Mingfeng Chang,Min Wang,Fugui Ha,Yixing Zhang,Jianzhong Pei,Jiupeng Zhang

doi:10.3390/ma13184120

Abstract

Asphalt rubbers mixed with untreated and plasticized crumb rubbers and a compounding coupling agent were investigated in this study. The low-temperature rheological properties of asphalt rubbers at different aging levels were tested using a dynamic shear rheometer (DSR). An interconversion between linear viscoelastic material functions was used to obtain converted evaluation indexes for the asphalt rubbers at low temperatures. Lastly, the physicochemical characteristics and the microscopic morphology of the asphalt rubbers were evaluated using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), respectively. In conclusion, the storage moduli of the asphalt rubbers containing heterogeneous crumb rubbers increased with the plasticized crumb rubber content and the aging level. The converted relaxation moduli were consistent with the change trend of the storage moduli, and the relaxation rate decreased as the plasticized crumb rubber content and the aging level increased. The process of mixing the base asphalt with crumb and plasticized crumb rubbers was physical blending, and the effect of aging on the absorption peak change of asphalt rubber with plasticized crumb rubbers was less than that of asphalt rubber with ordinary crumb rubbers. Aging deteriorated the blending between the crumb rubber and the base asphalt, and a distinct interface appeared between the crumb rubber and the base asphalt. The particle cores of the plasticized crumb rubber in the asphalt rubber were difficult to maintain. Furthermore, as the plasticized crumb rubber content increased, more fine particles stripped off the plasticized crumb rubber after aging.

Highlights

Crumb rubber prepared by waste rubber tires can be effectively combined with a base asphalt in asphalt rubber pavement, which saves resources and presents an environmentally sustainable treatment for hundreds of millions of waste tires produced each year
There are great differences in the compositions of crumb rubber due to the different composition of waste tires, which affects the performance of asphalt rubber [1,2]
The resulting short molecular chains can move and unfold in the base asphalt, which improves blending with the base asphalt

Summary

Introduction

Crumb rubber prepared by waste rubber tires can be effectively combined with a base asphalt in asphalt rubber pavement, which saves resources and presents an environmentally sustainable treatment for hundreds of millions of waste tires produced each year. There are great differences in the compositions of crumb rubber due to the different composition of waste tires, which affects the performance of asphalt rubber [1,2]. The poor compatibility between crumb rubber and asphalt in a traditional asphalt rubber results in low performance. Plasticization of untreated crumb rubbers cleaves existing cross-links. The resulting short molecular chains can move and unfold in the base asphalt, which improves blending with the base asphalt.

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Methods

Results