Preliminary Study of Molding of Expanded Clay
Fang, H. C.
Studies were attempted to obtain expanded clay from local materials. Results of the preliminary experiments are summarized as follow. Clay powder and saw dust are well mixed (1:5 v/v) first. A small amount of the material then was put into a grain-formation-machine. Small clay grains were obtained during the rotation of the machine and mist-spraying of water inside. At this time, the mixed material as previously described was gradually added in a small amount into the machine to increase the size of the grain until the size reached 10~18 mm. The prepared grains were dried at room temperature and then baked in the oven. In the beginning of baking, the door of the oven must be open to allow the release of excess moisture and smoke wastes. When the temperature reached 500℃, the door was closed. Expanded clay was obtained after 7-hrs. of baking at 1000℃. The exterior and absorbability of expanded clay were good for culture. The hardness of expanded clay were not hard enough when baked in a brick kiln because the temperature of the kiln was lower then 1000℃. Due to lack of enough adhesion in the field soils, they are not suitable for the preparation of expended clay.
Accepted for publication: June 3, 1991.