Study On The Application Of Steel Slag In Asphalt Mixture

China produces a large amount of steel slag every year,which not only occupies land resources,but also destroys the ecological environment.Therefore,making effective use of steel slag is of great significance to resource regeneration and green development of road engineering.Firstly,the basic properties of coarse-grained steel slag and fine-grained steel slag are studied through experiments,and the application of steel slag in asphalt mixture is discussed according to the characteristics of steel slag;The high-temperature stability,low-temperature crack resistance,water stability and volume stability of AC-10 steel slag asphalt mixture are studied through experiments,and the influence differences and influence mechanism of two different types of steel slag with coarse particle size and fine particle size and different steel slag content on road performance are analyzed,so as to give suggestions on mixing content;Based on the macro test results,the grey correlation analysis method is used to study the correlation degree between the basic performance of aggregate and the road performance of asphalt mixture,in order to provide technical reference for the application of steel slag asphalt mixture through the performance of aggregate;The expansibility of steel slag asphalt mixture is further studied,and the prediction model is established by using MATLAB software tool to further explore the expansibility of steel slag in asphalt mixture,and the three-dimensional curved surface of "steel slag expansion rate-steel slag content-mixture expansion rate" is obtained.The estimated value of expansion rate of steel slag asphalt mixture can be obtained through the value of steel slag expansion rate and steel slag content,In order to obtain a better application mode of steel slag in asphalt mixture and make full use of steel slag in road engineering.The results show that:(1)the addition of coarse and fine steel slag can significantly improve the high temperature stability and water stability of asphalt mixture,and both show a trend of increasing first and then decreasing.At the same dosage,the high temperature performance and water stability of coarse steel slag asphalt mixture are better than that of fine steel slag asphalt mixture.(2)The low-temperature crack resistance and volume stability of coarse steel slag asphalt mixture gradually decrease with the increase of steel slag content,but the low-temperature crack resistance of fine steel slag asphalt mixture gradually increases with the increase of steel slag content.(3)In terms of volume stability,the content of coarse and fine steel slag is inversely proportional to the volume stability,but under the same content of steel slag,the expansion rate of coarse steel slag asphalt mixture is lower than that of fine steel slag asphalt mixture.(4)Baosteel roller steel slag has good production process and high performance index.When the content of fine steel slag is within 36%,the road performance of asphalt mixture can meet the specification requirements,but the high-temperature stability is close to the minimum value required by the specification when the content of fine steel slag is 54%,and the water stability does not meet the specification requirements.Therefore,it is recommended that the content of fine steel slag in asphalt mixture is less than 36%,and the best content is 18%;The road performance of asphalt mixture with the content of coarse steel slag less than 54% meets the specification requirements.When the content of coarse steel slag is 36%,it has the greatest effect on the improvement of road performance.Therefore,it is recommended that the content of coarse steel slag in asphalt mixture is within 54%,and the optimal content is 36%,while the utilization range of mixed steel slag is larger.Within 54%,all road performance can be met,and it has the potential to further improve the content range.(5)Through the grey correlation analysis,it is found that the crushing value of aggregate has the greatest correlation with the high-temperature performance of the mixture,and the average correlation is 0.74;The wear value has the greatest influence on the residual stability of the mixture,with an average correlation degree of 0.84,and also has the greatest influence on the low-temperature crack resistance of the mixture,with an average correlation degree of 0.82;The water absorption and Ca O content have the greatest correlation with the water stability of the mixture,and the average correlation is 0.80 and 0.69 respectively.(6)The content of fine steel slag less than 36%,coarse steel slag less than 54% and coarse and fine mixed steel slag can meet the requirements of asphalt mixture specification,and the expansion rate of soaking for 3 days is ≤1.5%;Improving the spalling resistance of asphalt to steel slag aggregate can reduce the volume expansion of the mixture to a certain extent,but it can not achieve satisfactory results under bad conditions or long-term pavement service conditions.Therefore,pretreatment such as aging should be done as much as possible before using steel slag,so as to increase the utilization efficiency of steel slag instead of natural aggregate in road engineering.