Chapter Seven - Utilization of Fly Ash in Ceramic Brickmaking

Abstract

The effects of the use of red ceramic clay, gang sand, and feldspar on the utilization of MSWI fly ash in ceramic brickmaking are tested. An orthogonal test, analysis of ceramic brick performance based on R20 and R32 and analysis of performance variation of bricks based on R20 as a function of temperature, ceramic brick microstructure variation and transformation of phases, and a leaching toxicity analysis of bricks based on R20, are described. Different raw materials including red ceramic clay, gang sand and feldspar are utilized separately to make ceramic brick in order to cover the treatment cost of fly ash. The major chemical constituents of red ceramic clay, such as SiO2 and Al2O3, can react at high temperature to form a large quantity of mullite and silicates, and improve the plasticity of the ceramic body. Gang sand had a high SiO2 content level, and this was a major component of the ceramic body. It can react with Al2O3, forming mullite and thus improving the physical performance of the product. Feldspar is conducive to the reduction of the sintering temperature for ceramic brick. Based on intuition and variance analysis, MSWI fly ash is the decisive factor in terms of the appearance of ceramic brick, while the influence of feldspar and the sintering temperature are similarly important for red ceramic clay. So, bricks based on R20 are chosen to analyze performance variation, microstructure, and phase altering as functions of temperature.