Suitability of carbonaceous shale and clay in the preparation of building bricks

The possibility of utilizing carbonaceous shale as a substitute for some clay content in bricks was studied. Briquettes were made from mixtures containing 100-20\% clay and 0-80 carbonaceous shale. The bodies were fired at 700, 800 and 900 degrees C and 2 hours soaking time at each firing temperature. The ceramic and physical properties of the dried and fired articles were investigated. The results revealed that the compressive strength and bulk density increase with the clay content as well as the firing temperature. On the other side, the porosity and water absorption show an opposite trend. Also, the linear shrinkage decreases with the amount of carbonaceous shale whereas the weight loss has no effect. It can be concluded that the clay can be substituted with 20-50\% carbonaceous clay to give building bricks with reasonable properties.