Study On Selective Absorption Behavior And Suppression Method Of Bituminous Components For Steel Slag

As a by-product of steelmaking,the resourceful utilization of steel slag has both economic and environmental benefits.Steel slag,which has characteristics of hard texture,rich angularity,and strong adhesion to bitumen,endues excellent road performance of its bituminous mixture.Meanwhile,the abundant pore structure of steel slag leads to its more obvious absorption effect on bitumen compared with natural aggregate,which will reduce the flexibility of bitumen membrane on surface of steel slag and thus affect the durability of bituminous mixture.Based on the above background,combining with the four components separation technology of bitumen,the research status of selective absorption behavior of bitumen at home and abroad were first analyzed.The physicochemical properties,rheological properties and thermal properties of bituminous components and the surface properties of steel slag were investigated,which established foundation for revealing the selective absorption behavior of bitumen to steel slag.Subsequently,the fluorescence effect of pore size of steel slag soaked in bitumen-toluene solution for 3days,15 days,30 days and 90 days was dynamically observed by fluorescence microscopy.What’s more,the nanoindentation technology was used to explore the distribution of bituminous components in the inner and outer surface of pores in steel slag.Finally,the properties of diatomite inhibitor was studied,and its inhibition effect on selective absorption of bituminous components for steel slag was discussed.The results indicated that the true percentage contents of four components separated from two bitumen are over 80%by solvent precipitation and chromatographic column method.Saturates,aromatics and resins show fluorescence effect under ultraviolet light,and the gray scale of aromatics is the smallest.Carbonyl groups only appear in aromatics compounds,which shows that aromatics are most susceptible to aging in four components.Saturates and aromatics with lower flow activation energy are more easily absorbed by the pore of steel slag.The thermal stability of saturates is the worst,followed by aromatics and resins.And asphaltenes own the best thermal stability.In the same bitumen,the pyrolysis products of heavy components are more complex than that of light components.Only the pores of steel slag soaked for 90 days show obvious fluorescence effect,which indicates that the occurrence of selective absorption behavior needed a certain deadline.Among the four kinds of steel slag specimens,steel slag procured from Hubei province and coated with bitumen with 80–100 penetration displays the widest distribution of fluorescence brightness and the highest intensity under ultraviolet light.The inner surface of slag pore is composed of light components with good fluidity,such as saturates and aromatics.While its outer surface is mainly distributed as heavy components with high modulus.Steel slag with more abundant pore structure procured from Hubei province has smaller modulus range than that of steel slag procured from Guangxi province.This is due to it can absorbs more light components with smaller modulus.There was no obvious phenomenon of component separation in steel slag specimens coated with diatomite modified bitumen.Diatomite with OH~-group and many nano-scale pore structure can inhibit the selective absorption behavior of bituminous components for steel slag by absorbing light components in bitumen.