Use of fly ash in ceramic tiles: elastic properties during firing

Abstract

Two green ceramic materials were studied during heating from room temperature to 1100°C. One material (CG) contained clay (60 mass %) and grog (40 mass %), while the other (CGF) contained clay (60 mass %), grog (20 mass %), and fly ash (20 mass %). The investigated green ceramics are a mixture of minerals (kaolinite, illite, muscovite, calcite, and quartz). The main improvement of the mechanical properties between 20 and 300°C is due to the liberation of physically bound water. In the temperature region from 300 to 900°C very small changes of the sample volume are observed, and Young’s modulus slightly increases. From 900 to 1100°C, the sintering and creation of new phases causes a large shrinkage of the sample volume, and Young’s modulus dramatically increases its value. The total shrinkage of the sample volume during heating is ~6% for CG and ~24% for CGF. The relative change of Young’s modulus is ~220% for CG and ~190% for CGF.