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Unburnt clay building products

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Developing unburned clays for construction

Unburned clay used for the building industry has two major drawbacks. One it is brittle and two, it is soluble in water. These shortcomings have been addressed in a research programme that intended to make unburned clay suitable for a wider range of building applications.

Industrial Technologies icon Industrial Technologies

Traditionally clay undergoes a kilning process whereby it is subjected to high temperatures in order to harden and make it more suitable as a building material. Kilning is however, an expensive process that increases the cost of clay products considerably. To reduce associated costs, researchers have investigated means by which they could adapt unburned clay to be used as a suitable substitute for many building purposes and materials. Unburned clay (clay that has not been treated through heat) has basically two shortcomings; it is brittle and is soluble in water. This makes them inappropriate for such applications as insulating walls, flooring, roofing, panelling and decorative exteriors. In developing the water resistance properties of unburned clays, researchers discovered that linseed oil stabilised loams performed very well. While other additives such as bitumen and cement also performed well, they did not have the low environmental impact than linseed oil has. The oil-based additive gave clays the appropriate waterproofing qualities for external use such as façade slabs, roof tiles and external plasterwork. Because of their extreme brittleness unburned clays could not previously be used for wall-mounted panelling or tiling, and would break either upon mounting or during transport. To improve their physical properties many natural products were evaluated as an additive to loams. Wood fibres were found to impart the best physical strength to unburned clays and the developed prototypes produced better strength than did non-additive clays. Aside from their physical improvement, both elasticity and impact resistance were enhanced. Additional results founded from this research were the accumulation of knowledge about the manufacture of loam mixes, properties and production techniques. Knowledge that directly translates to improved unburned clay products which should make them more desirable for use within the construction industry.

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