Effect of Desulfurization Process Variables on the Properties of Crumb Rubber Modified Asphalt

Abstract

A large number of waste tires are in urgent need of effective treatment, and breaking waste tires into crumb rubber powder for modifying asphalt has been proved as a good idea to solve waste tires. Crumb rubber modified asphalt not only has good high and low temperature performance, durability, and aging resistance but can also reduce pavement noise and diseases, which has wide application prospects. In this study, crumb rubber powder was desulfurized by mechanochemical method to prepare desulfurized crumb rubber modified asphalt. During the desulfurization process of crumb rubber, the effects of desulfurization process variables including desulfurizer type, desulfurizer content, and desulfurization mixing temperature and time were considered, and then the physical properties of modified asphalt were tested. The test results showed that after mixing crumb rubber powder with desulfurizer, the viscosity of crumb rubber powder modified asphalt can be reduced. Moreover, the storage stability of crumb rubber powder modified asphalt could also be improved by mixing crumb rubber with desulfurizer. Based on the physical properties of crumb rubber powder modified asphalt, the desulfurization process of selected organic disulfide (OD) desulfurizer was optimized as follows: the OD desulfurizer content was 3%, the desulfurization mixing temperature was 160 °C, and the mixing time was 30 min. In addition, Fourier infrared spectroscopy analysis was carried out to explore the modification mechanism of desulfurized crumb rubber powder modified asphalt. There is no fracture and formation of chemical bonds, and the modification of asphalt by crumb rubber powder is mainly physical modification.

Effect of Activation Modes on the Property Characterization of Crumb Rubber Powder from Waste Tires and Performance Analysis of Activated Rubber-Modified Asphalt Binder

“…According to the Chinese standard "Standard Test Methods of Bitumen and Bituminous Mixtures for Highway Engineering" (JTG E20-2011), the penetration (T0604), softening point (T0606), ductility at 5 • C (T0605), rotational viscosity at 180 • C (T0625), elastic recovery (T0662), and softening point difference (∆) (T0661) of the activated crumb-rubber-powder-modified asphalt binder were tested. The techniques used and test conditions were detailed in the previous study [11].…”

“…The crumb rubber powder used in this study was the crumb rubber sample with 30 mesh provided by Guangxi Transportation Science and Technology Group Co., Ltd., Nanning, China, which was obtained by the normal temperature crushing method. According to the macro-and micromorphology of crumb rubber from the original appearance and scanning electron microscopy (SEM) in the previous study [11], the surface of the crumb rubber powder is rough and angular. Meanwhile, due to the crumb rubber powder being roughly sieved, it is composed of crumb rubber powder with different particle sizes.…”

“…Based on the existing literature [11], the asphalt binder modified by activated crumb rubber powder could be prepared, and according to the previous process exploration, the detailed steps were adopted to prepare the activated crumb-rubber-powder-modified asphalt binder.…”

“…At present, the commonly used crumb rubber powder activation methods include physical activation methods, such as the microwave method and ultrasonic method [9], chemical activation methods [9], the biological method [10], etc. In addition to the above activation methods, mechanochemical methods using chemical adjuvants are also applied to the activation of crumb rubber powder [11]. Many researchers have believed that the storage stability and workability of crumb-rubber-modified asphalt binder prepared from rubber powder have been significantly improved after desulfurization activation [12,13].…”

Study on the Aging Mechanism and Microstructure Analysis of Rice-Husk-Ash- and Crumb-Rubber-Powder-Modified Asphalt

“…From the 1930s, the utilize of rubbers from waste rubbers as an additive in the asphalt mixture [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. Because of the ability of crumb rubber powder (P) to enhance the asphalt binder and mixture performance [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ], therefore, using of crumb rubbers recently increased widely in construction pavement as a probable solution in minimizing waste tires and the disposal areas. Many researchers used composite-modified asphalt containing P and different modifiers, and they examined the characteristics of the composite-modified asphalt through number of micro-analysis methods and property tests [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ].…”