Multiscale Study On Paving Performance Of Waste Cooking Oil Based Bio-Asphalt Mixture Compound Modified By OMMT

In order to cope with the global shortage of petroleum resources and realize the sustainable development of asphalt pavement technology,the new material technology of bio-asphalt based on biomass resource utilization has been widely concerned in recent years.Biomass oil can be extracted from renewable biomass by rapid pyrolysis or fractionation and can completely or partially replace petroleum asphalt.In recent years,the development of new bio-asphalt materials derived from waste cooking oil（WCO）has been widely studied.However,it is necessary to improve the paving performance of bio-asphalt derived from WCO due to its insufficient high-temperature rutting resistance.In addition,the current research of new bio-asphalt materials is mostly focused on the scale of asphalt binder and the study on bio-asphalt mastic,mortar and mixture scale is insufficient.Therefore,it is of great significance to conduct multiscale research on paving performance and function improvement of WCO based bio-asphalt mixture,which is conducive to promoting low-carbon,green and sustainable development of road infrastructure construction in China.The objective of this research is to conduct the multiscale study on paving performance of WCO based bio-asphalt mixture compound modified by Organic Montmorillonite（OMMT）.Based on asphalt rheological test method,the linear viscoelastic properties,intermediate temperature fatigue and high temperature creep properties of compound modified bio-asphalt binder and its mastic under different aging conditions were studied;Through the asphalt mixture test to explore the impact of WCO and OMMT on the asphalt mixture paving performance,the effective relationship between key performance indexes of asphalt material at different scales was systematically analyzed.The improvement effect of OMMT on the paving performance of WCO based bio-asphalt material was evaluated.The main conclusions of this thesis are summarized as follows:（1）Under different aging conditions,the addition of bio-oil significantly reduces the dynamic shear modulus and rutting resistance of base asphalt,but it can enhance the anti-fatigue cracking ability of asphalt,thus increasing the fatigue life of asphalt;The addition of OMMT can effectively improve the dynamic shear modulus,high temperature elasticity and rutting resistance of bio-asphalt,but weaken its fatigue resistance.The deepening of aging degree can inhibit the elastic enhancement effect of OMMT on asphalt at high temperature,shorten the high viscosity interval of asphalt,and enhance the elastic properties of asphalt.Aging and bio-oil can increase the stress sensitivity of asphalt,while OMMT can significantly increase the stress sensitivity of asphalt.（2）Under different aging conditions,the addition of bio-oil reduces the dynamic shear modulus and high temperature rutting resistance of base asphalt mastic,and enhances the fatigue resistance of base asphalt mastic;OMMT can maintain the low temperature viscosity of bio-asphalt mastic while improving its dynamic shear modulus and high temperature elasticity.The dynamic shear modulus and rutting resistance of bio-asphalt mastic can be restored to a level better than that of base asphalt mastic when OMMT and bio-oil are equally mixed,and the modification effect is significantly better than that of asphalt binder.The enhancement of elasticity and modulus of OMMT in low frequency and high temperature region will be weakened with aging degree.The conclusion that the fatigue damage curve of asphalt is independent of loading rate is also applicable to asphalt mastic materials.（3）Under the same designed asphalt content,the addition of bio-oil improves the low temperature performance of asphalt mixture and has no effect on its water stability,but reduces high temperature stability significantly.The addition of OMMT improves the water stability and rutting resistance of bio-asphalt mixture,but reduces the low temperature performance.The J_nr index and fatigue life prediction model of asphalt mastic was established with powder/binder ratio as control variable and J_nr index and fatigue life as dependent variable.In addition,the flow number of asphalt mixture has a poor correlation with J_nr index of asphalt,but shows a better correlation with J_nr3.2index of asphalt mastic.So,it is more reasonable to recommend the asphalt mastic J_nr3.2to indicate the asphalt mixture performance at high temperature.