Reducing the density of fired ceramic products

Fired brick is one of the most widespread building materials, in the manufacture of which, in addition to strength, great emphasis is placed on the thermal insulation capacity of products. Reduction in bulk density is essential to further improve thermal insulation performance. During our work, in addition to adding sawdust of different fractions, we reduced the bulk density of the fired ceramic samples by mixing 10, 20, and 30 vol% expanded perlite. For the experiments, clay masses were prepared with a laboratory pan mill with a moisture content of 22 wt%. The formed and dried samples were fired at 870 °C for 4 hours. The body density of the samples decreased from 1708 to 1295 kg/m3 as the mixing rate of expanded perlite increased. The coefficient of thermal conductivity decreased significantly, the lowest value was 0.16 W/m·K. Thermal insulation capacity can be improved without significant reduction in compressive strength, by mixing expanded perlite.