Carbonate-containing clays in brick-making mixes: Optimisation with respect to frost resistance

Abstract

An experimental investigation followed by mathematical modelling has been performed to determine the maximum content of sandy-carbonate clay material which may be added to brick-making mixes to achieve a frost resistant product. A series of mixes with variable composition were prepared and fired at 960°C and 1000°C respectively and were then tested for water absorption and diametral strength. The samples were exposed to a freezing and thawing cycle and those which passed the cycling were tested for diametral strength. Mathematical models for the measured characteristics as a function of raw material composition were determined using regression analysis and the database was refined by microstructural studies. The models were optimized using geometric programming and the optimum quantity of carbonate-containing clay was determined. The predictions were proved by experiments.