Effect of by-pass cement dust on the properties of clay bricks

The suitability of the mixture of by-pass cement dust as non plastic material and the clay for the production of bricks was tested. Three mixtures having the compositions 100/0, 90/10 and 80/20 (wt.\%) clay - cement dust were investigated. Hand moulded briquettes were dried and fired for 2 hours at 600, 700, 900 and 1000 degrees C with firing rate 2.5 degrees C min(-1). The physical and mechanical properties of the dried and fired articles were measured. The results show that the substitution of 10 wt. \% clay by cement dust increases the gas permeability of the fired bricks, which prevents bloating, and increases the crushing strength of bricks with firing temperature up to 1000 degrees C. The substitution of 20 wt.\% cement dust brings the decrease in the crushing strength.