Introduction

The TG-DTA analysis for Clay 4 is typical of disordered kaolin with total weight loss of about 11.0%.

Peak/°C	Reaction
99.2	Loss of physical adsorbed water
340.8	Weight loss due to decomposition of organic content
550.0	Dehydroxylation of kaolin to metakaollin
951.2	Transformation of metakaolin to spinel

Generally, the corresponding weight loss due to the dehydroxylation of kaolin to metakaolin gives an indication of the amount of clay minerals that are present in the sample. A pure kaolin sample has a theoretical weight loss of 13.9%. The degree of sharpness of the last peak, Peak A and Peak B gives an idea of the orderliness of the kaolin structure. Clay 3 is a well- ordered kaolin as Peak A is narrow and sharp while Clay 4 is a disordered kaolin as Peak B appears broad. The orderliness of the kaolin structure affects the clay's dry strength. Generally disordered clays have higher dry strength than well-ordered ones.