Preparation and reaction mechanism of red mud based ceramic simple bricks

Abstract

In order to utilize solid wastes, ceramic simple bricks with high performances were made from industrial solid wastes such as red mud, fly ash and poor clay shale as main raw materials in this paper. The phase compositions and microstructures were tested by XRD, SEM and EPMA. The experimental results show that the water absorption is 45.64%, the porosity is 58.91%, bulk density is 1.29 g·cm−3, compressive strength is 54.91 MPa, bending strength is 29.52 MPa, freeze-thaw resistance is 29.28 MPa, specific heat capacity at constant pressure is 1.31 J·g−1·K−1, thermal diffusivity is 5.89×10−3 cm2·s−1, and thermal conductivity is 1.15×10−2 W·cm−1·K−1. These effects of additives and preparation process to the properties and microstructures were discussed in detail. The reaction mechanism was also discussed. The results of the reaction mechanism show that there has wollastonite and feldspar generated during the process of firing while Ca gathered around the feldspar, and then Ca would displace K and generated cacoclasite.