The use of tannery waste in the preparation of clay roof tiles

Dried tannery waste (TW) powder was added in weight percentages ranging from 0 to 35% to replace the raw mix used for the preparation of roof tiles. This raw mix is composed of three different types of clays, feldspar, and grog. The samples were prepared by 15.6% mixing with water and molding in cuboid steel molds, the amount of mixing water being deduced from plasticity measurements. The dry samples were tested for linear shrinkage and mechanical strength. Firing was carried out at temperatures ranging from 1000 & DEG;C to 1150 & DEG;C in a muffle furnace following a pre-determined heating schedule. The fired samples were tested for sintering characteristics, efflorescence, frost resistance and mechanical strength. The results proved that it was possible to substitute up to 10% of the original mix by tannery waste powder to obtain roof tile samples on firing at 1100 & DEG;C abiding by ASTM C 1167 Standards for grades 2 and 3 roof tiles.