Properties Of Coal Based Superhard Asphalt And Road Performance Of Modified Asphalt

Coal based superhard asphalt(SHA)is a solid waste residue generated by the direct coal liquefaction process,accounting for approximately 30% of the raw coal.The direct coal liquefaction process has become the mainstream coal refining technology due to its green environmental protection and high conversion rate,but it also generates more residues.The stacking and disposal of these residues poses severe environmental pressure and urgently requires proper disposal.After research,it has been found that applying it to the field of roads is an effective way of resource utilization.In order to achieve the large-scale environmental protection utilization of coal liquefaction residue and provide better cost-effective asphalt modifiers and modified asphalt technology,this study mainly conducts experimental research and evaluation of coal based ultra hard asphalt used for road asphalt modification.This article combines the principles and characterization methods of materials science,as well as the evaluation methods of asphalt and asphalt mixtures,to systematically analyze and study the material characteristics,environmental characteristics,asphalt modification effects,and mixture performance of coal based superhard asphalt;The road performance and construction characteristics of SHA modified asphalt were verified based on specific engineering sections.The main research conclusions are as follows:(1)Research on the elemental composition,component characteristics,environmental friendliness,and related physicochemical properties of SHA.Compared with SK-70 base asphalt,SHA has a large C/H ratio,a large aromatic carbon ratio,a high aromaticity,and a much higher degree of unsaturation than the base asphalt.S mainly exists in the combined state,and the molecular degree is more complex.There is a significant difference between the components of SHA and SK-70 matrix asphalt.The high content of asphaltene leads to a harder texture,higher softening point,lower ductility and penetration,and a preference for high-temperature performance;The content of insoluble matter is relatively high,and the ash content is higher than that of the base asphalt.In terms of environmental protection,the contents of polycyclic aromatic hydrocarbons pollutants such as pyrene and benzopyrrole in the top three SHA contents are lower than those specified in the Identification Standard for Hazardous Wastes-Identification of Toxic Substance Content: GB5085.6-2007.SHA also has no environmental pollution problems in the production of modified asphalt,mixing and paving of mixtures.(2)The influence of coal based superhard asphalt(SHA)on the single modification of asphalt has been clarified.Revealed the influence of SHA material composition on modified asphalt.SHA can improve the high temperature performance of asphalt,improve the aging resistance and reduce the temperature sensitivity,but has adverse effects on the low temperature performance and fatigue performance of asphalt;SHA can effectively improve the interfacial adhesion ability between asphalt and alkaline or acidic aggregates.When the SHA content is5%,the adhesion level between asphalt and granite can reach level 4;The use of SHA has broadened the range of aggregate selection.With the increase of SHA content,the saturated and aromatic content of modified asphalt gradually decreases,while the content of resin and asphaltene gradually increases.Due to its high content of asphaltene,the presence of asphaltene in SHA can improve the high-temperature performance of asphalt.However,the high brittleness of asphaltene is easily inherited from the entire modified system.In addition,SHA contains a large amount of minerals,unconverted coal and other organic solvent insoluble substances,resulting in an increase in the viscosity of modified asphalt and a further decrease in penetration and ductility.(3)Developed SHA and polymer composite modified asphalt.The composite SHA modified asphalt further enhances the high-temperature performance of the modified asphalt,with a softening point of nearly 80 ℃,and all high-temperature performance indicators surpassing SBS modified asphalt.The low-temperature performance of composite SHA modified asphalt has been significantly improved,with a ductility test of 37 cm at 5 ℃,effectively solving the problem of lack of ductility.Through PG grading tests,it was found that the PG grade of composite SHA modified asphalt can vary between PG76 and PG88.(4)Comprehensively analyzed and characterized the road performance of the mixture,clarified the impact of SHA on the performance of the mixture,and recommended a reasonable amount of SHA;And the experimental section was paved.The coal based composite modified asphalt has good road performance and obvious advantages in high-temperature stability.The best effect is to control the dosage of SHA at 10%-15%.At this time,the comprehensive road performance effect is most prominent,but the dosage should not be too much,and the maximum dosage should not exceed 20%,otherwise it will affect the performance of the original asphalt mixture.The engineering application of SHA modified asphalt has been achieved,effectively achieving the dual improvement of solid waste resource utilization and road servicelevel.