Research On The Treatment Method Of Steel Slag Expansion And Road Performance

In recent years,with the development of China’s iron and steel industry,steel slag emissions are also increasing year by year.A large amount of steel slag is directly piled up in the open air,which is not only a waste of land resources,but also causes environmental pollution.Therefore,reasonable and effective utilization of steel slag is an inevitable requirement for the sustainable development of iron and steel industry.Experimental research and engineering examples show that volume expansion is the main factor limiting the large-scale application of steel slag in road engineering.In this paper,Handan Iron and Steel Group Co.,Ltd.slag as the research object.Firstly,the expansion property of raw steel slag is studied,and then the effects of different treatment methods on the expansion property of steel slag are studied by controlling the presoaking time at normal temperature,the proportion of soil added,and the proportion of soil added after adjusting the gradation.On the basis of the expansibility meeting the specification requirements,the unconfined compressive strength,resilience modulus,and California load-bearing ratio tests of the soil-mixed steel slag mixture are carried out to further study the road performance of the steel slag mixture.The main research results are as follows:(1)The swelling rate of the raw steel slag is 5.97%,which is higher than the requirement of the code.Therefore,it is necessary to carry out swelling treatment on the raw steel slag before it can be used in road engineering.(2)Preimmersion treatment at room temperature can restrain the expansion of steel slag and improve the volume stability of steel slag.With the increase of preimmersion time,the expansion of steel slag decreases gradually,but the effect of immersion time on the expansion of steel slag will gradually weaken.(3)The expansion of steel slag can be inhibited by adding silty clay to steel slag,and the expansion rate of steel slag mixture decreases with the increase of the proportion of soil.(4)The dilatability of steel slag can be reduced by adjusting the grain size of steel slag(the particle size of steel slag is less than 4.75mm)and adding soil.When the proportion of soil is 30%,the expansion rate of steel slag mixture is 1.88%,which meets the requirements of the specification.On the basis of this ratio,the expansion rate of steel slag mixture with optimized ratio is 1.68%,which meets the requirements of the specification by adding cement of 5%(compared with the mass of soil).(5)Considering the volume expansion and road performance,it is determined that the optimal treatment method to suppress the expansion of steel slag is to screen out the particles with particle size less than 4.75 mm,and add 30% silty clay and 5% cement(mass ratio with soil)in steel slag.The steel slag mixture prepared by this treatment method can be used in the bottom base of medium and light traffic grade and the embankment of the first grade highway.