Recycling of polished tile waste as a main raw material in porcelain tiles

The manufacture of traditional porcelain tiles is often associated with a large amount of ceramic wastes during the polishing stage. These wastes need to be properly handled due to the corresponding environment problems. This paper aims to evaluate the possibility of reusing the polished tile waste as a main raw material to produce porcelain tiles. The prepared specimens with various amounts (10-70 wt.%) of the polished tile waste were fired at 1100-1180 °C. The sintering behaviors of fired specimens were examined by linear shrinkage, water absorption and bulk density. The flexural strength of fired specimens was measured by the three-point bending method. The test results show that the sample with 50 wt.% polished tile waste fired at 1120 °C has the superior performance (i.e., water absorption of 0.12%, bulk density of 2.49 g/cm3 and flexural strength of 47 MPa), which meets the requirement of porcelain tiles according to the ISO 13006 standard. Thus, the polished tile waste can be effectively reused in porcelain tiles as a main and low-cost raw material by fast firing at low temperature. The X-ray diffraction result indicates that introduction of the polished tile waste into porcelain tiles facilitates the formation of mullite phase. In addition, the relationship between the microstructure and strength of the optimal sample was also discussed.