Study On The Properties Of Biodiesel-Pyrolysis Wax Warm Mix Recycled Bitumen And Its Mixture

With the proposal of the "dual carbon" strategy,energy conservation,environmental protection and sustainable utilization of resources have gradually become the green development concepts adhered to by various industries.The recycling of recycled asphalt pavement is an important development direction of pavement maintenance,and recycling technology is also developing towards diversification.Warm mix recycling technology is a combination of warm mix technology and regeneration technology,which can alleviate the secondary aging of old asphalt in the hot mix recycling process,low RAP material content,and reduce energy consumption and asphalt smoke generation.At the same time,the rational use of waste plastics and kitchen waste is also an urgent problem to be solved.Therefore,under the principle of solid waste resource utilization and waste control,this thesis uses biodiesel extracted from waste plastic cracking wax and kitchen waste as asphalt modifier to carry out the research on the properties of modified asphalt,and the main research contents and conclusions are as follows:(1)Taking simulated aging asphalt as the research object,biodiesel recycled bitumen was prepared,and the optimal content of biodiesel was determined to be 3.3% according to the three major indexes and Brinell viscosity test regression analysis.Four kinds of pyrolysis wax content of warm mix recycled asphalt were prepared,and it was found that the content with good performance indicators and the lowest temperature sensitivity was 5%.(2)Starting from the rheological properties of bitumen,the synergistic effect of biodiesel and pyrolysis wax in bitumen was studied.The higher the temperature of the multiple stress creep recovery test,the greater the strain generated by the asphalt,and the non-recoverable creep flexibility Jnr of the 5% WORA specimen was the smallest among the asphalt samples.The 68℃ rutting factor of 5% WORA specimen in temperature scanning was about 1.47 times that of 3.3% ORA;the fatigue life calculated by the VECD model showed that biodiesel could significantly improve the fatigue life of bitumen,while the pyrolysis wax would be reduced;the modulus main curve fitting effect of 5% WORA specimen was the best in 40℃ main curve fitting based on WLF equation,which could better reflect the viscoelasticity of warm mix recycled bitumen in a wider frequency range.(3)Based on the evaluation of macro-rheological properties,the microscopic properties of asphalt were analyzed.In fluorescence microscopy,the lytic wax is well dispersed;The SI value of sulfoxide index of 3.3% ORA sample decreased by 11.8%,while the CI value of carbonyl index increased by 6.7%,and the addition of pyrolysis wax significantly reduced the strength of carbonyl and sulfoxide.Compared with recycled asphalt,the asphaltene and gum of warm mix recycled bitumen increased by 3.4% and2.65%,while the saturated content and aromatic content decreased by 1.26% and 2.45%,respectively.The interface adhesion work of basalt-bitumen is about 1.28 times that of granite-asphalt,and the adhesion work of recycled bitumen and two bedrocks is greater than that of warm asphalt;the heat flow rate and glass transition temperature Tg values of asphalt indicate that biodiesel and pyrolysis wax can improve the low-temperature viscoelasticity of aged asphalt.(4)Based on the analysis of asphalt cement,three RAP content gradations were designed to verify the performance of warm mix recycled asphalt mixture.Compared with the compaction temperature of hot mix,30% RAP-W is reduced by 10℃,50% RAPW is reduced by 20℃,and 70% RAP-W is reduced by 10℃;The larger the RAP content,the worse the high temperature performance,and the 30% RAP-W dynamic stability is the largest;The amount of RAP increased,and the bending strain of the recycled asphalt mixture increased first and then decreased,while it gradually decreased after warm mixing.Compared with the TSR of mixtures at all levels,the TSR of mixtures with 50%RAP content was the largest.The fatigue life of the mixture peaked when the RAP content reached 50%,but the fatigue life decreased after warm mixing.The fracture energy increased first and then decreased with the increase of RAP content,and the 50% RAPW fracture energy increased by about 32.04% compared with 50% RAP-H.The flexibility index shows the same trend as the fracture energy.Comprehensive comparison,when the RAP content is 50%,the performance of the mixture is better.