Study On The Surface Modification Technology Of Steel Slag And The Performance Of Modified Steel Slag Asphalt Mixture

In recent years,the country has vigorously built highways.A large number of highway constructions need to consume a large amount of natural stone,which will cause shortage of natural resources and environmental pollution.Steel slag as a relatively large volume of industrial solid waste,has excellent physical and mechanical properties such as angularity,high hardness and strength,high polishing value,and wear value of Losangeles is small,and can be used as an asphalt mixture aggregate.On the other hand,steel slag is generated at a high temperature of 1600°C.The structure of f-CaO and f-MgO is very dense,and the hydration rate is very slow.When steel slag comes into contact with water,it will produce volume expansion and thus reduce the long-term stability of steel slag asphalt mixture.The research and application of steel slag as a road engineering material over the years has shown that the expansion of steel slags is the most important factor affecting steel slags to be used widely.The study of the method for suppressing the expansion of steel slag conforms to the urgent need of engineering practice,and has important academic significance and practical significance.Based on the problem of expansion of steel slag,in this paper,the surface modification of steel slag is performed using modified material I and modified material II.The modified aggregate expansion and mechanical properties and the dynamic modulus of the modification steel slag asphalt mixture specimens after water erosion were studied.The pH,ICP-OES and scanning electron microscopy were used to measure the pH of the leachate,the ion concentration of the leachate,and the structure change of the aggregate interface after water erosion.The mechanism of deterioration of the modification steel slag after water erosion was analyzed.The following main conclusions were obtained:(1)After modification of modified material I and modified material II,the two kinds of modified steel slag have good mechanical properties.The SEM image of the modified steel slag shows that the surface of the ISS(modified material I modified steel slag)is rough,and there are a lot of pores in the transition zone and the interface.The OSS(modified material II modified steel slag)has a smooth surface,structure is very dense,fewer defects in the interface transition zone,and plays a good effect of water barrier effect.(2)The resistance to water erosion and cracking of the modification steel slag is significantly higher than that of the untreated steel slag,and the modified material II modified steel slag has the highest anti-explosion performance.The two modification methods improve the mechanical properties of the steel slag,and the modified steel slag remains good mechanical properties after water erosion.The modified treatment not only improves the dynamic modulus of the steel slag asphalt mixture,but also reduces the attenuation rate of the low frequency dynamic modulus after water erosion,and has little effect on the high frequency dynamic modulus of the steel slag asphalt mixture.(3)Hydration reaction of modified layer and steel slag after water erosion.The hydration products accumulate and fill the transition zone between the modification layer and the interface,make the structure of the interface transition zone dense,gradually reducing the water infiltration channel,and helping to strengthen the modification layer.The ability to block water not only improves the resistance to water erosion and cracking of steel slag,but also helps maintain the ability to resist pressure and wear after water erosion.