Study On The Properties Of Magnesium Sulfur Oxide Cement With Large Steel Slag

In recent years,the steel industry of our country develops rapidly and the output of steel increases greatly,steel slag is the main byproduct in the process of steelmaking.The accumulation of steel slag not only occupies land resources,but also has a serious impact on the ecological environment.The alkaline leachate contained in steel slag can penetrate into the interior of the surface,pollute water and soil,and destroy the environment.At present,the use of steel slag resources is more and more common in our country,the problem of steel slag resources waste and pollution of environment is increasingly serious.In order to solve the problem of the steel slag accumulation causing waste of resources and pollution environment,it is urgent to improve the utilization of steel slag.Magnesium oxysulfate cement has the advantages of light weight,early strength,high strength,good fire performance and so on.At the same time,it can use industrial and agricultural waste as filling material.It is a low-carbon and environmental protection green cement.In this thesis,the effects of different proportions of 50wt.%and 100wt.%by weight of LBM of steel slag on three kinds of magnesium oxysulfate cement containing different modifiers were studied,among which oxalic acid,EDTA-2Na and triethanolamine were added to magnesium oxysulfate cement respectively.The effects of steel slag content,carbonation curing and different modifiers on the compressive strength of magnesium oxysulfate cement were analyzed.The phase composition and microstructure of the sample were described by XRD,SEM,FTIR and ICP.The experimental results show that the compressive strength of magnesium oxysulfate cement decreases after adding steel slag.The compressive strength of magnesium oxysulfate cement mixed with 50wt.%and 100wt.%steel slag by weight of LBM were 26.9MPa and 17.8MPa respectively.The addition of oxalic acid improved the compressive strength of the blend system most obviously.The compressive strength of the sample mixed with 1wt.%oxalic acid were 38.7MPa and26MPa,respectively,and further increased to 55.8MPa and 47.1MPa after carbonation curing.The improvement of compressive strength is due to the carbonation curing accelerated the hydration of C₂S in steel slag,forming Ca-Mg-C amorphous materials and magnesium-containing carbonate minerals,thus improving the strength of cement test block.Secondly,the curing performance of magnesium oxysulfate cement on chromium ions,which are harmful to steel slag,are explored,and the results show that magnesium oxysulfate cement modified with oxalic acid has the best adsorption effect on hexavalent cadmium ions,with an leaching rate of 0.0201mg/L and a leaching rate of 0.0151mg/L after carbonization.Second,EDTA-2Na had a leaching rate of0.408mg/L,and a Leaching rate of 0.396mg/L after carbonization.Triethanolamine was poor,the leaching rate was 2.498mg/L,and the leaching rate after carbonization reached 2.244mg/L.Through comparison,it is found that the use of oxalic acid for modification can not only meet the GB 5084-2021"Farmland Irrigation Water Quality Standard",but also ensure the performance of steel slag products mixed with magnesium oxysulfate cement.