Rheological Performance Of Compound Modified Waste Cooking Oil Based Bio-asphalt

The huge demand of petroleum asphalt for asphalt pavement construction and maintenance and the non-renewable of asphalt resources restrict the sustainable development of future road infrastructure construction.In recent years,biomass resources have gradually been widely attracted in the field of transportation all over the world.The biomass based heavy oil after treatment such as crop straw,bark branches,waste cooking oil,and various kinds of animal manures are very similar to petroleum asphalt in chemical composition.Possible replacements of bio-oil to petroleum asphalt for pavement construction will solve the dependence of road industry on traditional petroleum asphalt.The recycle of the waste cooking oil（WCO）（commonly known as“gutter oil”）is widely used among the all kinds of renewable biomass energy.The application of WCO based bio-asphalt and related research work to improve its paving performance will effectively promote the transformation of transportation industry from resource consumption to the environment friendly type.Up to now,the high temperature performance of WCO based bio-asphalt is generally lower than the traditional petroleum asphalt.Therefore,how to improve and enhance its functional paving performance is the bottleneck problem of restricting the application and promotion for bio-asphalt technology in the future.This work aims to improve the paving performance of WCO bio-asphalt by compound modification of the Organic Montmorillonite（OMMT）.The chemical properties,viscoelastic characteristics,as well as the damage resistance of bio-asphalt were systematically studied.Meanwhile,statistical analysis was conducted for the rheological properties of Bio/OMMT modified asphalts under multiple aging conditions to establish the predictive performance models by considering the influence of“bio-oil”and“OMMT”dosage.The rheological prediction model of Bio/OMMT modified asphalt is to support the recycling of waste cooking oil in pavement industry in the future.The main conclusions are summarized as follows:（1）OMMT addition can effectively reduce the“softening”effect from bio-oil on the dynamic modulus of petroleum asphalt.The bio-oil is the dominant factor that affecting the temperature shift factor of Bio/OMMT modified asphalt.The higher dosage of bio-oil exhibits the stronger temperature sensitivity,while the OMMT has no significant effect on the temperature sensitivity.（2）The crossover frequency and G-R index are well correlated to the rutting factor（|G^*|/sinδ）.While their relationship to the fatigue factor（|G^*|·sinδ）are obviously lower,therefore,they can only qualitatively describe the fatigue resistance.（3）The bio-oil addition can significantly reduce the high temperature performance of petroleum asphalt whereas OMMT addition can effectively make up for the lack of rutting resistance of bio-asphalt.Especially when bio-oil and OMMT were used in the equal addition,the high temperature performance of Bio/OMMT modified asphalt can be basically maintained compared to the petroleum asphalt.（4）The OMMT addition has a negative effect on the fatigue properties（crack resistance and fatigue life）of bio-asphalt.Similarly,when the bio-oil and OMMT are used in the equal addition,the Bio/OMMT modified asphalt can reach or approach the fatigue performance of petroleum asphalt.However,it is still necessary to pay attention to the adverse effects from the long-term aging.（5）It is found that the asphalt molecules enter the structure gallery of OMMT structure to form the sandwich structure.There is a good consistency between the changes of the micro layer spacing and the macro viscoelastic index as well as the damage characteristic of the Bio/OMMT modified asphalt.（6）Based on the various predictive models of binder rheological properties,in terms of linear regression（LR）,response surface model（RSM）and BP neural network（BPNN）models,both the mode fitting and prediction accuracy of J_nr is higher than other indexes.While the model fitting results and predictive reliability of the G-R index is the worst.（7）The rheological properties of the Bio/OMMT modified asphalt can be well fitted from LR model.However,the effect of aging reduces the fitting accuracy for several rheological parameters.In the LR model application,the prediction reliability of binder damage index is relatively higher（R² reaches about 0.8）,while the prediction of viscoelastic index is generally poor.（8）Compared with the LR model,the RSM model fitting is improved under different aging conditions.In the RSM model application,the prediction reliability of binder damage characteristic is relatively higher（R² reaches above 0.85）while the viscoelastic index prediction is relatively lower.（9）The BPNN model fitting accuracy of rheological properties of Bio/OMMT modified asphalt gradually generally decreases with the oxidative aging,which show the obvious aging sensitivity.However,the damage characteristics display relatively better fitting results in various aging condition.