Study On Preparation And Performance Of Super-hard Modified Emulsified Asphalt

In recent years,with the increasing number of vehicles and overloading,the problem of pavement diseases is becoming increasingly prominent,and the highway maintenance is becoming particularly important.Reasonable maintenance measures can greatly improve the service life of the pavement,so the pavement maintenance material modified emulsified asphalt has become a research hotspot.However,the traditional modified emulsified asphalt has poor high temperature performance and serious pavement rutting damage,so the hard asphalt with excellent high temperature rutting resistance is gradually coming into people’s vision.Super hard asphalt SHA(super-hard asphalt)is the product of coal direct liquefaction residue,is a kind of high quality modifying agent,after the modification of matrix asphalt superhard modified asphalt is a kind of hard asphalt,test research shows that in improving the performance of high temperature at the same time affected the performance of low temperature,and material availability,price cheap,less pollution to the environment,So it is very necessary to try emulsifying the super hard modified asphalt.Firstly,the preparation method of SHA modified asphalt is determined by optimizing the process preparation conditions,the content of granular SHA was 4%～16%and that of flake SHA was 4%～24%.On this basis,the high and low temperature properties of granular and flake SHA were studied through conventional tests of three indexes,dynamic shear rheometer temperature scanning test and low temperature bending creep test,and PG grading was obtained.The test results show that SHA addition can effectively improve the penetration degree and softening point of base asphalt,and the rutting factor G~*/sinδalso keeps increasing,and the high-temperature performance of ultra-hard modified asphalt is obviously improved;The creep stiffness S and creep stiffness change rate m obtained from low temperature bending creep test have little change range,indicating that the low temperature performance of ultra-hard modified asphalt is not significantly reduced,PG performance classification of super hard modified asphalt was obtained.Based on the preparation of super-hard modified asphalt,the preparation technology of emulsified asphalt was explored.The influencing factors were analyzed and evaluated from the aspects of shear rate,oil-water ratio,category and dosage of emulsifiers and stabilizers,etc.The super-hard modified emulsified asphalt was prepared by modifying first and then emulsifying.Then the properties of vaporized residue such as conventional and low temperature properties,the storage stability,viscosity and adhesion with coarse aggregate of fresh emulsified asphalt emulsion were evaluated.The optimal preparation scheme of super-hard modified emulsified asphalt was determined as follows.The performance of super hard modified emulsified asphalt mixture was studied.Firstly,the aggregate selection and gradation optimization of emulsified asphalt mixture were studied.In this study,the aggregate is basalt with better robustness and durability,and the mineral powder is basalt mineral powder.Two typical gradations A and B were selected,and it could be seen from the percentage of mass fraction that the particle size of gradation B was larger than that of gradation A.The results of mixing test show that the pulp is good when the added water is 5%～6%.After 1h and 6d wet wheel wear tests,the wet wheel wear values of gradation A and B were rapidly reduced.It could be seen that gradation B had better abrasion resistance and water damage resistance.From the perspective of environmental protection,SHA as a modifier can turn industrial waste into treasure and save resources.From the economic point of view,coal direct liquefaction residue is a kind of industrial waste.The material is easy to obtain and the price is low,so it is suitable for large-scale use.