Reducing energy consumption and CO2 emissions in ceramic brick production with diatomaceous earth

In this study, diatomaceous earth (DE) was investigated as a potential additive for reducing brick-firing temperature, along with its behavior in different clay mixtures. Changes in firing temperature influence the decomposition of carbonates in clays, thus a high (CC), a medium (CM), and a carbonate-free (CF) clay were used as raw materials. DE was added to the clays at 0, 5, and 10 wt%. The specimens were fired at firing temperatures of 775, 800, 825, 850 and 875 °C. In addition to the raw material examinations, Pfefferkorn plasticity, shrinkage, water absorption, bulk density and compressive strength tests were also performed. The addition of DE reduced the plasticity of the clays. Along with increased water absorption, the density of the fired samples decreased by 2 5 %. The most notable outcome of incorporating DE was the considerable enhancement in compressive strength: the CM clay exhibited a 39 57 % increase, while the CC clay showed a 10 17 % improvement compared to the additive-free samples at various firing temperatures. For the CF clay, however, the addition led to a reduction in strength. By utilizing this effect, the firing temperature can be reduced from 850 °C to 800 °C for the CM clay, and from 850 °C to 825 °C for the CC clay, while maintaining the compressive strength. Based on the energy calculations carried out for CM clay, the specific energy consumption during brick production can be reduced with 79.57 kJ/kg, while simultaneously lowering CO₂ emissions by 0.005 kg/kg. • In brick clays, diatomaceous earth enables lower firing temperature while maintaining strength. • The effect of diatomaceous earth on compressive strength depends on clay composition. • The additive reduces density and shrinkage for clays examined. • Energy demand and CO 2 emissions can be decreased during production. • The use of diatomaceous earth contributes to more sustainable brick manufacturing.