Evaluation of asphalt modified with bio-oil and high rubber content: Low temperature and short mixing time production condition

Abstract

High rubber content modified asphalt needed high production temperatures due to the high viscosity, but the viscosity and production temperature could be decreased by adding bio-oil. Producing rubber and bio-oil modified asphalt (BRMA) with good performance under low temperatures and short mixing time had significant environmental contributions. Therefore, this study prepared BRMA with crumb rubber content of 20 % and bio-oil content of 5 %, 10 %, and 15 % under the low-temperature (160 °C) and short-time (30 min) shear conditions. The rheological characteristics of BRMA were evaluated by conventional and rheological property tests. The interaction mechanism among rubber, bio-oil, and asphalt was assessed with the Fourier Transform Infrared test (FTIR) and Fluorescence Microscope test (FM). The addition of bio-oil had a significant impact on reducing the increase in asphalt viscosity that was typically caused by rubber modification. The high-temperature performance, elastic performance, and low-temperature performance of BRMA were significantly improved. The PG grade of neat asphalt was PG 64–22, 20 %R + 5 %Bio was PG 70–34, 20 %R + 10 %Bio was PG 70–34, and 20 %R + 15 %Bio was PG 64–40. Under the condition of low mixing temperature and short reaction time, the FTIR test found that no new absorption peak appeared, and the bio-oil, rubber, and asphalt were mainly physical mixing. Through the FM test, it was found that rubber reacted with asphalt at different degrees, and some crumb rubber that did not fully react ensured that asphalt still had good elastic properties and deformation resistance at high temperatures. The research provided theoretical guidance for similar application scenarios, such as dry process rubber modified asphalt.