Design Of Steel Slag Asphalt Mixture And Experimental Research On Leaching Of Heavy Metal Elements

Using steel slag instead of natural aggregate for the construction of asphalt pavement can not only save natural stone,but also reduce environmental pollution caused by mountain quarrying.However,steel slag contains heavy metal elements(mainly including Pb,Hg,Cd,As,Cr,Ni,Cu,Mn,Zn,etc).After the steel slag is used in the construction of road projects,whether it will cause environmental pollution under the scouring and soaking of rainwater remains to be studied.Based on this,this article focuses on the heavy metal leaching behavior of steel slag and steel slag asphalt mixture to determine whether it will cause environmental pollution.Through the analysis of the physical and mechanical properties,volume stability,microstructure,etc,it is concluded that the crushed value and weared value of steel slag are better than limestone,and it is determined that the steel slag can be used in asphalt mixture instead of natural aggregate.In view of the leaching behavior of heavy metal in steel slag,the trend of leaching of heavy metal elements(Fe,Mn,Zn,Cu,Cr)with time under different pH soaking solutions of steel slag with different particle sizes was analyzed.The results showed that:within a certain immersion time:The leaching amount of heavy metals of Fe,Mn,Zn,Cu,and Cr all showed an increasing trend with the extension of the immersion time,and the smaller the particle size,the larger the specific surface area,and the greater the amount of heavy metal leaching.Combining the range analysis and variance analysis in the orthogonal experiment,the order of the influence of Fe,Zn,Cu heavy metal leaching amount is pH>days>particle size,Mn heavy metal leaching amount is pH>particle size>days,Cr The primary and secondary order of influence on the amount of leaching is days>pH>particle size.According to the leaching test results,when steel slag is stacked directly without treatment and used as subgrade filler,if it is soaked in acid rain for a long time,attention should be paid to the influence of the steel slag soaking liquid on the surrounding water resources.The mass conversion of steel slag was carried out based on the volume method,and the design and road performance of AC-13 and PAC-13 under different asphalt were studied.On this basis,through heavy metal leaching test,the influence of different factors on heavy metal leaching of AC-13 and PAC-13 steel slag asphalt mixture was analyzed.The results show that:for the three elements of Fe,Mn,and Cu,the leaching amount of heavy metals in PAC-13 is much higher than that in AC-13.For the same structure,the leaching amount of heavy metals in different asphalts has little difference,and with the increase of asphalt content,the leaching amount of heavy metals decreases.In addition,with the increase of temperature,the leaching amount of Fe and Cu increased significantly.The leaching amount of Mn at 60℃ was much higher than that at 20℃ and 40℃,and the leaching amount at 20℃ and 40℃ had little difference.According to the results of the leaching test,all kinds of steel slag asphalt mixture have no risk of heavy metal leaching pollution.