Experimental Study On Lime-silica Fume-fly Ash Stabilized Unaged Steel Slag-gravel Mixture Pavement Base

Steel slag is the waste of the steel industry,which has similar physical properties with natural stone.There have been many studies on the application of natural aged steel slag instead of natural stone in road base.However,natural aging of steel slag causes problems such as occupation of land resources,environmental pollution,but also pollutes the environment.This thesis studies the feasibility of applying unaged steel slag to pavement base material,which has important practical significance for developing circular economy and protecting environment.In this thesis,the swelling property of unaged steel slag of Handan Iron and Steel Co.,limited by the test,the swelling rate of steel slag is 4.5%,which does not meet the specification requirements of steel slag used in road base.After the test,it is found that the expansion rate of steel slag after adding 3% or more silica fume meets the specification requirements.The steel slag-gravel graded aggregate is designed in reference to the specification,and the volume stability tests of different mixing ratios of steel slag-gravel pure aggregate,Lime-fly ash stabilized steel slag-gravel mixture,and Lime-silica fume-fly ash stabilized unaged steel slag-gravel mixture are carried out.The results show that the suitable steel slag content in second ash stabilized steel slag-crushed stone mixture is only 20%.The maximum allowable content of steel slag in Lime-silica fume-fly ash stabilized unaged steel slag-gravel mixture can reach 60%.The road performance indexes of the Lime-silica fume-fly ash stabilized unaged steel slag-gravel mixture were tested by orthogonal test method,and the effects of the ratio of second ash,second ash to silica ash and steel slag content on the road performance were analyzed.Considering the volume stability,various road performance and the utilization of large amount of steel slag,this thesis suggests that the best mixing ratio of three ash in Limesilica fume-fly ash stabilized unaged steel slag-gravel mixture is 1:3～1:4 ratio of two ash and 17:3 ratio of two ash to silica ash,and the content of steel slag should be 40%～60%.