Microstructure and mechanical properties of clay bricks: comparison between fast firing and traditional firing

Clay bricks fired using a traditional slow cycle and an innovative fast cycle were compared from the microstructural and mechanical viewpoints. Tests were performed on both a laboratory and a semi-industrial scale. For products with equivalent water absorption, fast firing leads to higher bend strength, lower bulk density, greater mean pore size, and improved frost resistance. Firing shrinkage and pore size selection seem to depend on carbonate content and the clay particle size. Maximum temperatures are 50-100(degree) C higher in fast firing, which would make it possible to obtain products with equal or even better properties than those achieved with traditional firing cycles. M. Dondi and 1. Venturi are in CNR-IRTEC, Istituto di Ricerche Tecnologiche per la Ceramica, National Research Council, via Granarolo 64, 48018 Faenza, Italy. M. MarsigH is in Agenzia Polo Ceramico, via Granarolo 62, 48018 Faenza, Italy. Manuscript received 6 August 1997; infinal form 23 April 1998.