Effects of ultraviolet exposure on physicochemical and mechanical properties of bio-modified rubberized bitumen: Sustainability promotion and resource conservation

Abstract

Promoting the use of scrap tire rubber and bio-modifiers in outdoor construction such as road pavements requires an in-depth understanding of their resistance to solar radiation which causes premature aging in outdoor constructions. Aging changes bitumen's colloidal stability, increasing the content of asphaltenes, and decreasing the content of aromatics as aging progresses. Bitumen's changes during aging include oxidation, aromatization, chain scission, and carbonization, which alter bitumen's chemical, physical, and mechanical properties. Here, we examine how exposure to ultraviolet radiation changes the physicochemical and mechanical properties of bio-modified rubberized bitumen (BMR) containing various bio-modifiers. To do so, the physicochemical and mechanical properties of rubberized bitumen specimens containing bio-modifiers from castor oil (CO), corn stover oil (CS), miscanthus oil (MS), wood pellets oil (WP), and waste vegetable oil (WVO) were examined before and after they were exposed to ultraviolet radiation for 50, 100, and 200 h. The study results showed that the resistance of the abovementioned bitumens to aging caused by ultraviolet exposure was highly dependent on the source of the bio-modifier. The aging resistance was highest for CO-BMR and WP-BMR, followed by WVO-BMR, CS-BMR, and MS-BMR. This was attributed to the presence of unsaturated groups in CO and WP, which acted as sacrificial agents. In the case of WP, the improvement can also be attributed to the presence of high content of furfural. It should be noted that furfural has been used as a specialty antiaging chemical in industry. The study outcomes help manufacturers select modifiers for rubberized bitumen to enhance its resistance to UV aging and promote sustainability in construction.