Research On The Preparation Of Permeable Steel Slag Asphalt Mixture And Interface Mechanism

The high content of f-CaO in steel slag leads to poor stability and grinding difficult. There is still no suitable solution for the the steel slag . In the view of the low utilization rate of steel slag, this paper used steel slag as aggregate and prepared the permeable asphalt mixture in order to study the influence of different factors on its road performance. Quantitative determination of asphalt-aggregate by boiling method, the interfacial behavior of asphalt mortar was studied from the macroscopic and microscopic multi-scale, and the physical and chemical reaction mechanism of asphalt-aggregate system was revealed from the perspectives of thermal, mechanical and surface physical chemistry. The research indicates:Orthogonal test analysis of the particle size of steel slag had the most significant influence on Marshall porosity, stability and flow value, followed by the asphalt aggregate ratio, and the influence of filler was the weakest. The best combinations are the particle size distribution of steel slag from 4.75 to 9.5 mm, the asphalt aggregate ratio as 6.7%, and the filler is steel slag powder. The results of road performance showed that the stability of the water stability test is 90.68%, the Marshall stability is 9.12 kN and the dynamic stability is 6350 times/mm, the volume expansion rate is 0.49%, permeability coefficient of 60.61ml/s, are in line with pervious asphalt pavement technical requirements(CJJT190-2012).With the increase of the void of steel slag aggregate, the porosity of single gradation permeable steel slag asphalt mixture gradually increased, the stability increased first and then decreased, and the flow value decreased first and then increased.The porosity of two kinds of particle gradation permeable steel slag asphalt mixture gradually increased, the stability decreased first and then increased, and the flow rate gradually increased. The porosity of three kinds of particle gradation permeable steel slag asphalt mixture gradually increased, the stability decreased firstly and then increased, and the flow value gradually increased.The steel slag aggregate-asphalt adhesion grade is 5, and control the other different factors, indicating that steel slag aggregate and asphalt adhesion is well; the slag aggregate particle size, asphalt mixing time, steel slag substitution increase will increase the steel slag aggregate-asphalt interface adhesion; the water time, freeze-thaw cycle increase will reduce the steel slag aggregate-asphalt interface adhesion, the more the number of cycles, the faster the adhesion decreased.Infrared spectroscopy analysis of asphalt and steel slag interaction, at 3500cm-1 ?3750cm-1 have some new absorption peak, generated by the amine and amide N-H stretching vibration, SiO-H stretching vibration, indicating that there was chemical reaction between asphalt and steel slag, the material is inferred from the characteristic peak that the substance may be an organosilicon compound. The chemical composition of steel slag Fe2O3, mineral composition of steel slag Fe3O4, C2S, C3S are associated with asphalt chemical reaction, inferred from the characteristic peaks may produce organosilicon compound.The observation of the steel slag-asphalt interface by scanning electron microscopy(SEM) shows that the pits and texture characteristics of the steel slag particles provide a similar skeleton effect for the interface of the asphalt-steel slag aggregate. This effect can enhance the interfacial strength of the asphalt-aggregate and improve adhesion strength.The adsorption effect of steel slag aggregates on the asphalt was significantly higher than that of rock aggregates. The filler will promote the adsorption of aggregate and asphalt, and the promotion of slag powder is most significant; the initial adsorption is unstable, after stabilization, the equilibrium concentration is higher and the adsorption capacity is larger. The addition of water will leave the asphalt on the surface of the aggregate. From the asphalt - steel slag aggregate adsorption isotherm shape can be seen as a multi - molecular layer adsorption, which belongs to the physical adsorption type.