Research On Performance Of High Content Bio-asphalt Modified By Polyphosphate And Mixture

Asphalt pavement was widely used in modern road construction because of its excellent performance.As a cementing material,asphalt has contributed significant value to road engineering.However,asphalt is a non-renewable resource,so reducing usage or finding alternative energy sources is of great strategic importance.At the same time,the development philosophy of "environmental friendliness and resource conservation" should be met;this undoubtedly put forward higher requirements for road materials.In many scholars ’ studies,castor oil bio-asphalt was renewable and environmentally friendly,and petroleum asphalt has partly been replaced by castor oil bio-asphalt.The development of green road materials is the hot spot and focus of scholars at home and abroad.In order to realize the use of castor oil bio-asphalt in road asphalt and increase its utilization rate,polyphosphoric acid(PPA)was used to improve the high-temperature performance of bio-asphalt.At the same time,the conventional properties and rheological properties of the composite modified asphalt were tested to determine the best dosage and preparation method.Finally,this study carried out the composite modified asphalt mixture’s road performance,strength,and fatigue tests.Firstly,the preparation scheme of modified asphalt was determined by the orthogonal test with four factors and four levels.The four factors were the content of castor oil and PPA,shear time,and shear rate.The conventional properties and rheological properties were taken as evaluation indexes,and the effects of modifying modifiers and preparation conditions on the properties of asphalt were analyzed to determine the best preparation scheme.Meanwhile,the modification mechanism was revealed by infrared spectroscopy.Secondly,to promote the practical application of high content of bio-asphalt modified by polyphosphate,further study the performance of asphalt mixture.The road performance of mixture was verified through rutting,low-temperature bending,immersion Marshall,and freeze-thaw splitting tests the road performance of mixture.Finally,because fatigue cracking was one of the main structural failure modes of asphalt pavement,the fatigue performance of mixture was studied to improve the completeness of antifatigue design of pavement materials.In different loading rates and stress states,the strength test of mixture was carried out to establish the strength model.The strength yield surface was established by using the Desai yield surface theory at different loading rates.The S-N fatigue equation was used to characterize the fatigue performance of high content bio-asphalt modified by polyphosphate mixture under different stress states,and a new method for fatigue performance analysis of high content bio-asphalt modified by polyphosphate mixture was provided.This study carried out a systematic analysis of high and low-temperature performance,modification mechanism,road performance,mechanical performance,and fatigue performance.The feasibility of its practical application is explored by analyzing its performance,which provides a scientific basis for expanding the efficient application of waste and promoting the development of green transportation.