Fabrication, microstructure and properties of bricks fired from lake sediment, cinder and sewage sludge

Lake sediment, cinder and sewage sludge were used as raw materials to prepare three types of fired brick samples. Measurements were made on the plasticity index, oxide composition and mineral composition of raw materials and the linear drying shrinkage, water absorption, bulk density, compressive strength, thermal conductivity and freeze-thaw resistance of the fired brick samples were investigated. XRD, SEM and MIP were used to analyze the phase composition and microstructure of bricks. It was found that sewage sludge can be used together with lake sediment and cinder to produce bricks which meet the requirements of Chinese specifications. The incorporation of cinder and sewage sludge into lake sediment reduced the linear drying shrinkage of adobe, but at the same time increased the water adsorption and lowered the compressive strength and the frost resistance of the fired brick. The difference in the properties of the three types of bricks can be explained from the characteristics of their microstructure.