Study On Hudration Performance Of Steel Slag As Supplementary Cementitious Material Under Different Hydrothermal Condition

China is a big steel producer, so lots of industrial scrap steel slags are created erery year.As a result of treatment and comprehensive utilization technical reasons, most steel slag isabandoned in the yard, cultivated land occupied and cause damages to the environment. Steelslag contains water hard gel chingnish C2S and C3S,so it is regarded as a Portland cementclinker of burning. Based on this, This paper focuses on the Steel slag powder which is one ofthe main wastes in Steel industry as the research object. Under different hydrothermalcondition, Hydration characteristic of steel slag powder and Influence law of compressivestrength performance and Sulphate erosion resistance performance and the volume stabilitywere studied. The test methods are including XRD, SEM, strength test, Ion dissolutionexperimentation test, Mortar stick method and Rapid test for sulfate resistance of cement. Atthe same time, it is compared with sand powder and fly ash, and to discusse the possibility ofsteel slag powder substitute sand powder applied to evaporate a Portland products. Resultsshow that:（1） The particle of Steel slag powder is most the ball polyhedron of irregular shape, thesurface is rough, more trenchant edges, the surface smooth degree is worse than fly ash,better than sand powder, and steel slag powder particles is finer than sand powder, it’s showthat the gender is easier than sand powder. For steel slag powder and sand powder in thedetermination of active Si and Al, under80℃hydrothermal curing condition, Si and Aldissolution of steel slag powder increased more than20℃and its early activity got motivated,it is known that in80℃hydrothermal curing condition, the early activity of the steel slagpowder is inspired better and the consumption of Ca（OH）2volume is more than sand powder,high temperature effectly stimulates the activity of steel slag and improves its hydrationreaction degree. Grinding fine steel slag powder is as cement admixture, when the mixedquantity of scope is10%³0%, the impact of Standard consistency water for the cement isnot obvious, cement setting time is extended slightly, and it can improve the paste liquidity.（2） Under different hydrothermal curing condition, the compressive strength of cementmixed with steel slag powder cement, compared with that mixed with sand powder is higher,and is lower than that mixed with fly ash, meanwhile the compressive strength has a droptrend with the increasing of the mixed quantity, raising with the prolongation. Fixed mixingcontent is30%, the1d compressive strength in high temperature water increased10.18%thanthat in20℃temperature water raised3d, the3d compressive strength in high temperaturewater increased9.74%than that in20℃t emperature water raised7d; The steel slag powderand sand powder and fly ash complex when mixed with respectively, strength effect wasobvious than that only mixed with steel slag, especially steel slag powder and sand powder ismixed2:1or steel slag powder and fly ash is mixed2:1, the strength improved under20%, at the same time, in high temperature water the3d,7d strength increased more than30%compared with20℃. Combined with ion of dissolution test and SEM microscopic test,it isconfirmed that the activity stimulate degree of steel slag powder is higher in high temperaturewater maintenance condition than20℃, the reaction degree is better than sand powder andslightly less than fly ash, hydration degree and dense degree is better, so its strength is higherthan that of sand powder.（3） Sulphate Resistance is key investigation factors of the durability of cement, grindingsteel slag powder with Portland cement is to reduce the C₃A content, etc, it can contain theSO42-and C3A effective response, and effectively reduce Ca（OH）₂content of the cementsystem, improve the ability of sulphate resistance in cement. In the ratio of30%, The abilityof Sulphate Resistance in cement mixed with steel slag powder is better, especially whenthe steel slag powder mixed with sand powder by the proper of1:2, can further improvecapacity of Sulphate Resistance in cement, improve the durability.（4） Volume stability is one of the important factors when the steel slag is used for cement,Steel slag contains more free CaO, MgO, etc, under different water hydrothermal curingcondition, when cement mixed steel slag powder, because of micro expansion when the freeCaO rehydration produces in the process, and it can effectively suppress the dry shrinkage ofcement, not appear the phenomenas of expand, unequal dry shrinkage. When the mixing steelslag powder is10%, total dry shrinkage rate cement grinding60d can reduce by17.14%; themixing steel slag powder is30%, total dry shrinkage rate of cement grinding60d reduced by10.34%.At the same time, because of the waste ceramic powder has the dry shrinkageperformance, considering ceramic powder mixed with steel slag powder, it’s finding that ithas certain influence inhibitory effect to control the Volume stability of steel slag powder,especially when the steel slag powder mixed with ceramic powder by the proper of2:1,it’sgood.Through the research of grain shape and composition, strength, durability, volumestability, it can find that the hydrothermal curing condition is more conducive to grind theactivity of steel slag powder, steel slag has good strength, and ceramic powder on the steelslag powder inflation has certain inhibition effect, at the same time, the steel slag powder alsohelps to improve the Sulphate Resistance ability of the cement, making use of theseadvantages, it’s applied to replace the sand powder preparation of Cement concrete orsteamed to keep Portland products. Carrying out the comprehensive utilization research ofsteel slag, realizing the recycle of waste, it can save resources, and reduce environmentalload,so will have greater social benefits and economic benefits.