Preparation of autoclaved bricks made from low-silicon hematite tailings

The preparation of autoclaved bricks from low-silicon hematite tailings from western Hubei province was investigated.The results show that the optimum raw material composition is a mixture of 70% hematite tailings,15% lime and 15% sand.The optimum forming pressure is 20 MPa.The compressive strength,flexural strength,the compressive strength and mass loss after 15 times freezing-thawing of autoclaved bricks obtained under optimum test conditions are 21.20 MPa,4.21 MPa,18.36 MPa and 0.72%,respectively.The performances of autoclaved brick satisfies the standard of GB 11945—1999.Calcium silicate hydrate,tobermorite and hydrogarnet make main contribution to the strength of the autoclaved brick.They form network structure and shaped compact and solid framework through cementing particles of hematite tailings and yellow sands.