Research Of The Cementitious Property Of The Cementitious Material With Steel Slag And Granulated Blast Furnace Slag Composite Admixture

Steel slag(SS) is a by-product produced during the steelmaking in the steel and iron plant, about90million tons of SS produced annually in China, while the effective utilization rate of which was only about10percent, the research and the effective use of SS were needed urgently. Treat the SS as a cement admixture was considered as an effective way to take advantage of the SS, research on the properties of the SS is insufficient, the utilization way is restrictive. This thesis mainly research on the analogous silicate materials such as SS, granulated blast furnace slag(GBFS)’s cementitious property,focusing on the hydration performance analysis and comparison of the hardened pastes associated with SS, which could provide theoretical foundation for the recycling use of SS as a cement admixture.In this paper, Xinyu hot stuffy SS(469m2/kg) was researched, the fundamental relevant properties of SS was studied, the comparison of the hydrated performance between SS and cement was studied, the results research showed that the mineral phase and the hydration products of SS and cement were alike, while the morphology and the structure of the hardened SS paste was different with that of cement, the number of hydration products of SS was much smaller than the cement in the same age, the results showed that compared with the cement, the SS had tiny cementitious property. This paper studies the cementitious properties of the composite powder of SS blended cement (SS-cement), the result showed that the species of hydration products of SS-cement was similar to SS, cement, while the the structure was different, the species of hydration products were Ca(OH)2, AFt crystals, C-S-H gel, further more, there were some kind of AFm,C-A-H gel and so on in SS-cement. Analyzing and comparing the non-evaporable water showed that there had been a mutual promotion between SS and cement.Results indicated that the achievement of GBFS, fly ash composite with SS on the mechanical behaviour of cement mortar was:GBFS>fly ash, the mechanical property of SS-GBFS binary complex was superior to single-doped SS or GBFS, even better than the reference cement without admixture, The species of hydration products of SS-GBFS-cement was similar to SS-cement excep some C-A-H and C-A-S-H.Comparing the TG-DTA drawing of SS, cement, SS-cement, SS-GBFS-cement binder pastes, we can see that there are three main obvious exothermic peaks in these cementitious materials, corresponding to the dehydration or decarbonation reactions of different hydration products, respectively were the early dehydration endothermic peak of C-S-H gel and AFt crystal in range from100℃to200℃; the dehydration endothermic peak of Ca(OH)2in range from400℃to500℃; and the later period of C-S-H gel and AFt crystal’s dehydration endothermic peak, the decarbonation endothermic peak of CaCO3in range from600℃to900℃. Calculating and comparing the total mass loss of each sample hydrated at28day, it could be found that the total quantity of hydration products were cement>SS-GBFS-cement>SS-cement>SS.