| Lithomargic clay underlying Awaso bauxite deposits consists mainly of kaolinite and minor fractions of gibbsite. Gibbsite, useful as a source of alumina, was separated from kaolinite. Gibbsite was added to lithomargic clay in various amounts, using Mfensi clay as a binder, and fired at 1350?oC for 2?h. Linear firing shrinkage, density, porosity, water absorption and cold crushing strength were used to characterize the fired bricks. The mineralogical compositions in the fired bricks were analyzed by X-ray diffraction techniques. The results showed that increasing the gibbsite amount up to 40?wt% increased the firing shrinkage and density whilst the apparent porosity and water absorption values decreased. Increasing the gibbsite amount enhanced mullite and corundum formation whilst the formation of free-silica phases was inhibited. The cold crushing strength increased linearly with increasing gibbsite content.
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