The effect of kaolin and limestone on physical and mechanical properties at different temperature of wall tiles
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Date
2016-06
Authors
Anis Nadia Abdul Aziz
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Abstract
The effect of kaolin and limestone on wall tiles was studied to observe the physical and mechanical properties at different temperatures. Kaolin and limestone are two important raw materials in wall tiles body formulations. Single fast-firing cycles of ceramic wall tile processing have been widely employed. A basic composition was formulated to eliminate the variations in properties of other raw materials. The basic was then added with kaolin and limestone at certain compositions to complete 5 body formulations. During firing, kaolinite (Al2O3.2SiO2.2H2O) will undergo dehydroxylation forming metakaolinite (Al2O3.2SiO2). Metakaolinite will react with calcium oxide (CaO) which results from limestone decomposition to form crystalline phases such as gehlenite (Ca2.Al2.SiO7) and anorthite (Ca.Al2.Si2O8). The tiles were fired at three different temperatures which are 1010, 1030 and 1050°C to observe the changes in terms of properties as well as microstructure. SEM was used to to examine microstructural changes in the fired specimens. Addition of kaolin content shows the decreased in water absorption and apparent porosity and increased in shrinkage, moisture expansion and resulted in more mullite formation. Addition of limestone content shows the decreased in shrinkage and moisture expansion and increased in water absorption, apparent porosity and resulted in more anorthite formation. Increased in firing temperature resulted in lower water absorption, apparent porosity and moisture expansion while increased in firing shrinkage.