Published online by Cambridge University Press: 21 February 2011
Based on the characterization of 12 clay and 5 fly ash samples, samples were selected for the following laboratory scale experiments: preparation of raw mixes, determination of the correlation between water content and plasticity, rate-controlled sintering in a laser-dilatometer, DTA-TGA-analyses, preparation, firing and testing of bars. Laboratory experiments have shown that it is necessary to bind the soluble sulphates as barium sulphate under acidic conditions and bind the free lime as phosphate when wet production methods are to be used. A full scale experiment has been carried out, resulting in the production of 16,000 red bricks containing 33% fly ash by volume in the raw mix. These fly ash bricks look satisfactory and have 10% higher strength and 2% less density than the corresponding bricks without fly ash. The water extractable matter in the two kinds of bricks were compared. The bricks were used for constructing a wall with the purpose of investigating their weather resistance.