Effect of Aluminum Hydroxide Addition on Properties of Fired Refractory Clay Brick

Abstract

The pottery of Ratchaburi is very famous especially dragon jar which was fired by using dragon kiln. The kiln was made of unfired clay bricks, which its properties including high refractoriness, low thermal shrinkage and durable are desired. Aluminum hydroxide is an interesting material for improving brick’s properties, providing high active alumina (gamma-alumina) content after decomposition, high melting point and also reasonable cost. The study evaluated the effect of an additive, Al (OH)3, on the fried properties of refractory clay brick. In this study, four difference proportions of Al (OH)3 to clay , including 0:100, 25:75, 49:51 and 76:24 were studied. The specimens of 5x5x5 cm3 were formed by hand molding, then were fired at 1200, 1300 and 1400°C. The properties including refractoriness, volume shrinkage, strength, bulk density, water absorption, and slaking time were investigated. The samples of 25:75 ratio of Al (OH)3 to clay, which was fired at 1300°C exhibited high in refractoriness, low volume shrinkage of 5% and relatively low density of 1.69 g/cm3 as compared to those of 1400°C fired. Moreover, the moderate water adsorption of 15 % and useable compressive strength of 12.4 MPa was also observed. As a result, these properties suitable for using in firebox of dragon kiln of Ratchaburi province.