Green utilization of corn straw: Prediction of bio-oil liquefaction yield and application of bio-oil in asphalt

To achieve the sustainable and eco-friendly development of pavement materials, finding alternative materials to reduce the dependence on petroleum resources is desirable. In this study, bio-asphalt was prepared using liquefied products derived from corn straw. Firstly, the effects of liquefaction parameters on the liquefaction yield of straw bio-oil were explored, and a bio-oil liquefaction rate prediction model was constructed by combining the machine learning algorithm. Then, the composition of the bio-oil was characterized using Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS), while its thermal stability was analyzed through thermogravimetric analysis (TGA). Finally, the mechanism by which bio-oil influences both the conventional and rheological characteristics of bio-asphalt was examined. The results indicated that the liquid-solid ratio (LR) during the liquefaction process has the most significant impact on the bio-oil liquefaction yield of corn straw. Constructed corn straw bio-oil liquefaction yield model can predict the liquefaction accurately under various parameters, and the relative error of prediction is less than 5.51 %. The composition of bio-oil includes phenols, esters, and other components with high stability. It can maintain good thermal stability from 0℃ to 200℃, and its chemical composition resembles that of asphalt. The asphalt still retains its inherent properties with a 25 % bio-oil content, and the bio-asphalt exhibits good performance at both high and low temperatures. Moreover, the alcohols present in bio-oil significantly impact the consistency of asphalt, while esters are positively correlated with the asphalt’s performance at high temperatures.