Study Of Accelerators Of Steel Slag Used In Concret

The production of steel of our country has been at the first place in the world in resent years. Steel production of our country has reached 565 million tons in 2009. Steel slag is the main solid waste of steel industry.10-15 tons steel slag will be produced for every 100 steel produced. Because our country has low utilization rate of steel slag, lots of steel slag is stayed in steel corporations and occupied much field. Steel slag has much less active composition and its dense structure makes it hydrate very slowly, which make steel slag has low early strength and make bad effect on using of steel slag.This thesis mainly studies the effects of accelerators on activating early strength of steel slag. First, the Effect of mixing amount and specific surface area on properties of steel slag is studied; then, effects of single addition and combinated addition of many inorganic and organic accelerators to accelerating early strength of steel slag is studied and the best accelerator and its dosage is obtained.The results are as follows:Both sulfate-activators and alkali-activators can improve the early strength of steel slag cementitious materials; effect of compound alkali-activate agents and compound sulfate-activate agents on early strength of steel slag cementitious materials are better than single alkali-activate agent and single sulfate-activate agent; combination of alkali-activating and sulfate-activating has better effect on steel slag cementitious materials than alkali-activating or sulfate-activating. Organic has almost no effect to accelerating early strenth of steel slag and inorganic accelerators and organic accelerated combinated has much less effect in accelerating early strength of steel slag.The optimum combination of alkali-activator and sulfate-activator is CaSO4·1/2H2O and NaOH combinated in a proportion of 1% :0.4%, the 3d compressive strength is increased by 54.5%,7d compressive strength is increased by 15.2%.SEM of steel slag show that hydrate of steel slag is much less than cement, steel slag particles do not have hydrated after 3 days. C-S-H which is produced by cement enclosed steel slag particles, the structure of paste is very loose. From the XRD patterns of steel slag cementitious material which is added accelorators, steel slag produced more Aft.