A Study on Physical and Rheological Properties of Rubberized Bitumen Modified by Different Methods

Abstract

Crumb rubber (CR) manufactured from waste tires used in bitumen could improve bitumen performance and reduce environmental pollution. In this work, three different modification methods, pretreatment of the CR particles (microwave activation), warm mix additive (Sasobit), and trans-polyoctenamer (TOR) were used to improve the compatibility of CR with bitumen. Moreover, two other specimens, Sasobit and microwave activated and TOR and microwave activation were fabricated, and their performance was investigated. The softening point, elastic recovery, force ductility, rotational viscosity, temperature sweep, frequency sweep, and multiple stress creep and recovery (MSCR) tests were measured to evaluate the physical and rheological properties of rubberized bitumen. The results showed that TOR improved the physical properties of rubberized bitumen significantly but had a negative effect on the viscosity. Sasobit decreased the viscosity of rubberized bitumen considerably and improved the physical properties of rubberized bitumen moderately. Microwave treatment on CR had a negative effect on the high temperature performance and elastic recoverability of rubberized bitumen, however, attributing to the degradation and devulcanization effect of microwave on CR, the viscosity of rubberized bitumen was improved. From the results of composite modification, the influence of TOR on the performance of rubberized bitumen was more obvious than that of the microwave activation treatment. Moreover, the influence of Sasobit on its performance was less than that of the microwave activation treatment.

Laboratory Investigation of Aging Resistance for Rubberized Bitumen Modified by Using Microwave Activation Crumb Rubber and Different Modifiers

“…Therefore, the main reactions happening in STA can be divided into the aging of bitumen and the swelling and degradation of CR. The microwave irradiation broke down the external and internal chemical bonds of the CR partially [ 7 , 11 ]. The destruction of chemical bond accelerated the desulfurization and degradation of CR particles, and the light component in the bitumen absorbed by the swelling action was released partly.…”

“…The ductility of RBS was close to URB, and the difference was 5.5 mm. Sasobit primarily modified the molecular structure of free bitumen at high temperature, and the influence on the flexibility of rubberized bitumen at low temperature was influenced by the properties of CR and its reaction process with bitumen [ 11 ].…”

“…After microwave irradiation, the surface of CR became porous and uneven. This phenomenon can increase the reaction area and promote the swelling of CR in bitumen [ 11 ].…”

“…Warm mix additives (WMA) and pre-degradation CR were two effect methods to decrease the high viscosity of rubberized bitumen. Another method is to add reactive modifiers such as trans-polyoctenamer (TOR), the purpose of which is to improve the compatibility between CR and bitumen [ 11 ]. Previous studies proved that the effects of these methods on the compatibility between CR and bitumen were effective, while few studies focused on the aging resistance for rubberized bitumen prepared with these methods.…”

“…As the most common methods applied in the rubberized bitumen preparation, the author had evaluated the influence of the modification methods on the physical and rheological properties for rubberized bitumen in the previous study [ 11 ]. The result showed that the modification methods had significant influences on the rubberized bitumen properties.…”