Abstract: With Angang Qidashan unground iron tailings as aggregate mixed with cementitious materials of iron tailings, blast furnace slag, cement clinker and natural gypsum of level 3 step mixed grindings, the concrete blocks of iron tailings are prepared. The concrete blocks under direct standard curing, 56 ℃ then standard steam curing and 90 ℃ then standard steam curing are separately analyzed from aspects of its strength, hydration products and microstructure. The results show that compared with the standard curing, 56 ℃ steam curing can improve the block's strength at each stage, however 90 ℃ steam curing only improve the early block's strength and have a negative impact on the later strength. All curing methods can form the compact high-strength iron tailings material consisting of quartz, the un-hydrated C₃S and C₂S, hydration products CH, ettringite and C-S-H gel, but have a different impact on the hydrating and hardening process of the iron tailings concrete.

Key words: Qidashan iron ore tailings, Concrete block, Standard curing, Steam curing, Hydration products