CHANGES IN THE PHYSICAL PROPERTIES OF CERAMICS DERIVED FROM ANDESITE-BASALT AGGREGATE DUE TO DIFFERENT SINTERING TEMPERATURES

This study investigated the impact of sintering temperatures on the physical properties of ceramics fabricated from andesite basalt aggregate. The physical properties, including relative density, shrinkage, and colour of the samples, were examined to optimize the sintering temperature for the mass production of high-density ceramics. The study demonstrated that a slight variation of 10 ºC in the sintering temperature, within the range of 1040 to 1080 ºC, at a constant sintering duration of 1 hour, results in notable changes in the relative density, shrinkage, and colour of the samples. In addition to visual assessment, colour changes can be quantified using colour organization systems, such as the CIELAB colour space, which is standardized by the International Commission on Illumination (Commission Internationale de l'Eclairage - CIE). The CIELAB system characterizes colour using three parameters: L* for lightness, a* for the red-green intensity, and b* for the yellow-blue intensity. The characterization of sintered samples was performed using scanning electron microscopy, X-ray diffraction method, Archimedes method, digital caliper, and a spectrophotometer for the diffuse reflectance measurements in the 380–720 nm range with a 1 nm step size. The optimal physical properties were obtained in the sintered ceramic at the temperature of 1060 ºC for 1 hour, yielding a relative density of 99.5%, shrinkage of 12.8%, and colour coordinates in the CIELAB system of L*(32.0), a*(9.2), and b*(7.5). Owing to its exceptional physical properties and unique reddish-brown colouration, the polished sintered ceramic is ideally suited for manufacturing floor and wall tiles in construction.