CLAY
Clay is made up of two major components, silicon dioxide and aluminum oxide. The formation process is due to the erosion of the earth’s surface. The erosion of the rock is caused by the weather, which wears down the rock into small microscopic particles. Clay can be classified into two types; residual clay that could be dug up from its original place, and the second type is the transported clay, which is also called the sedimentary clay that was remove from it original location through erosion.
Clay is form in three ways; by chemical decomposition of rocks, such as granite, containing silica and alumina; by solution of rocks, such as lime stone which contain clayed impurities being soluble are deposited as clay; lastly by the way of disintegration and solution of shale. (“Shale: sedimentary rock formed by the consolidation of mud or clay, having the property of splitting into thin layers parallel to its bedding planes. Shale tends to be fissile, i.e., it tends to split along planar surfaces between the layers of stratified rock. Shales comprise an estimated 55% of all sedimentary rocks. The composition of shale varies widely. Shales with very high silica content may have been formed when large quantities of diatoms and volcanic ash were present in the original sediment. Large numbers of fossils in shales may give them a high calcium content; such shales may grade into limestones. Shales that contain a large percentage of alumina are used as a source of that mineral in the manufacture of cement. Shales containing abundant carbonaceous matter grade into bituminous coal. Oil shales are widely distributed in the W United States and may be a future source of petroleum.”)
The Columbia Electronic Encyclopedia,
Evaporation of all the water by firing to the temperature of 500 degree could remove all water content that had been trap and cannot be evaporated below 350 degrees. At this stage the molecules of the clay would collapse together and fill up the gaps between the spaces. This would give the clay hardness and strength. The process is called vitrification. At this stage the clay cannot return to it clay form or absorb water.
Clay is form in three ways; by chemical decomposition of rocks, such as granite, containing silica and alumina; by solution of rocks, such as lime stone which contain clayed impurities being soluble are deposited as clay; lastly by the way of disintegration and solution of shale. (“Shale: sedimentary rock formed by the consolidation of mud or clay, having the property of splitting into thin layers parallel to its bedding planes. Shale tends to be fissile, i.e., it tends to split along planar surfaces between the layers of stratified rock. Shales comprise an estimated 55% of all sedimentary rocks. The composition of shale varies widely. Shales with very high silica content may have been formed when large quantities of diatoms and volcanic ash were present in the original sediment. Large numbers of fossils in shales may give them a high calcium content; such shales may grade into limestones. Shales that contain a large percentage of alumina are used as a source of that mineral in the manufacture of cement. Shales containing abundant carbonaceous matter grade into bituminous coal. Oil shales are widely distributed in the W United States and may be a future source of petroleum.”)
The Columbia Electronic Encyclopedia,
Evaporation of all the water by firing to the temperature of 500 degree could remove all water content that had been trap and cannot be evaporated below 350 degrees. At this stage the molecules of the clay would collapse together and fill up the gaps between the spaces. This would give the clay hardness and strength. The process is called vitrification. At this stage the clay cannot return to it clay form or absorb water.
posted by Wei Zhong Kristoffer Tan at 6:24 PM
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