Research On Performance Of Bio-asphalt/Polyurethane Composite Modified Asphalt And Its Mixture

Petroleum asphalt is a subsidiary product produced in the process of petroleum refining.Petroleum is a non-renewable resource,and its reserves in the world continue to decrease.This will inevitably bring restrictions to the development of the road industry based on petroleum bitumen.There is an obvious supply contradiction with the large demand for asphalt materials in my country’s highway construction.Looking for materials that can replace or partially replace petroleum asphalt is conducive to sustainable and healthy development of the road industry.The challenge of endurance for future development is now at hand,and the exploration of new green road materials is imminent.As a new type of green road material,the research and application of bio-asphalt have made certain progress and development in recent years,and the types of bio-asphalt used are increasing.However,studies have shown that the blending of bio-asphalt with petroleum asphalt may have a softening effect and reduce the high-temperature performance of the asphalt binder,thus limiting the development of bio-asphalt in engineering applications.In this paper,castor oil bio-asphalt is used to replace part of petroleum asphalt,and polyurethane is added while keeping the total mass of castor oil bio-asphalt and petroleum asphalt unchanged,and multiple sets of bio-asphalt/polyurethane composite modified asphalt with different blending ratios are prepared.Indoor tests are used to determine the performance of the composite modified asphalt and the road performance of the asphalt mixture,and the microstructure of the asphalt is analyzed.The conclusions are as follows:(1)After the bio-asphalt and polyurethane are compounded,the penetration of the compound modified bitumen decreases overall,and the low-temperature ductility is greatly improved.When the ratio of bio-asphalt instead of petroleum bitumen to the polyurethane content is less than 1:0.3,the softening point of composite modified asphalt rises,and the anti-aging performance is also improved.(2)Through the rheological performance test,it can be found that the viscosity of the asphalt is increased after the addition of bio-asphalt and polyurethane;when the ratio of bio-asphalt to the polyurethane content is less than 1:0.4,the high-temperature rheological properties of the composite modified asphalt can be improved and the low-temperature rheological properties are greatly improved.After comprehensive consideration,it is recommended to use up to 15%bio-asphalt in high-temperature areas and at least 5%bio-asphalt to replace petroleum asphalt in low-temperature areas.(3)It can be seen from the results of infrared spectroscopy that two new functional groups are added after the addition of bio-asphalt and polyurethane,and the bio-asphalt-polyurethane composite modified asphalt has been chemically modified;through fluorescence microscope,it can be observed that the composite modified asphalt is uniformly mixed and forms a stable structure of mesh-filling.(4)The road performance test results of the asphalt mixture show that the high temperature performance,low temperature performance,and water stability of the bio asphalt/polyurethane composite modified asphalt are excellent,and the rheological properties of composite modified asphalt at high and low temperatures have the same changing trend as those of asphalt mixture at high and low.