Preparation And Performance Investigation Of ZnO/PPA/DOP Composite Modified Asphalt

By choosing a good performance,moderately priced modifier to improve the performance of asphalt,so as to improve the level of service of the road,is a more effective way to improve the performance of asphalt.Polyphosphoric acid(PPA)as a chemical modifier,the asphalt has a significant improvement in high temperature resistance.Dioctyl Phthalate(DOP),a plasticizer,is a chemical additive that can significantly improve the low temperature performance of asphalt,while the addition of nano ZnO can effectively improve the UV aging resistance of asphalt.In this study,PPA,DOP and nano ZnO were used as modified materials for the composite modification of asphalt.Firstly,based on the results of basic performance tests,the optimum dosing of modifiers was obtained by one-way analysis,extreme difference analysis and analysis of variance.Then each modified asphalt was aged in different ways,and the aging residues were subjected to rheological performance tests to evaluate the road performance of each modified asphalt by rheological test index.Finally,the microscopic characteristics of asphalt were analyzed by gel permeation chromatography test(GPC),Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy(SEM)and fluorescence microscopy(FM),and the mechanism of action of modifiers was investigated.The main findings are summarized as follows:(1)The optimum dose of modifier nano ZnO,PPA and DOP in single-doped modified asphalt was determined by basic physical property test and 135℃ Brinell rotational viscosity test,which were 0.5%,0.5%and 1.5%,respectively.(2)The orthogonal test design was carried out for the three modifiers as well as their dosing ranges,and the extreme difference and variance results were obtained by SPSS software analysis,and finally the optimal dosing of each modifier ZnO,PPA and DOP in the composite modified asphalt were analyzed:1.5%,0.5%and 1.5%.(3)The high-temperature performance of asphalt was significantly improved after mixing PPA and ZnO alone.After adding modifier DOP,the low-temperature properties of the as-sampled asphalt were significantly improved.However,after aging in different ways,the low temperature performance of DOP modified asphalt at different temperatures was reduced to different degrees.(4)The high and low temperature properties of single-mixed modified asphalt were all decreased to some extent relative to the pre-aging.The addition of modifier ZnO has improved the UV aging resistance of asphalt.Compared with other modified asphalt,the composite modified asphalt has the best aging resistance in different ways.(5)After the addition of PPA and ZnO,the proportion of asphalt macromolecules became higher.ppa,ZnO and asphalt were mainly chemically modified,and DOP was mainly physically modified in asphalt.znO modified asphalt had more surface folds,while PPA was more uniformly dispersed in asphalt,and PPA modified asphalt had a little doughy flocculent on the surface.