Abstract: MU15 dry-pressed burning-free bricks were made with iron tailings from Shaanxi as the main raw material, and by addition of a small amount of cement and a proper amount of river sands.The effect of the mass ratio of iron tailings to river sand, cement amount, water addition for mixing, forming pressure and chemical additives on their compression strength was investigated.The results indicate that their 28 d compression strength can reach 16.4 MPa when they are made of iron tailings at such conditions: a forming pressure of 15 MPa, a mass ratio of iron tailings to river sand of 1.25∶1.00, a cement amount accounting for 10% of the total dry solids, a water addition for mixing amounting to 8% of the total dry solids, and a naphthalene-based super-plasticizer content and a sodium gluconate content of 0.8% and 0.03% of the cement dosage respectively.Their other performance indexes are in conformity with the requirements in JC/T 422-2007 standard “Unfired Bricks Made of Tailings”.

Key words: Iron tailings, Dry-press unfired bricks, Compressive strength