Production of Electrical Porcelain Insulators from Local Raw Materials: A Review

This paper reviewed the production of electric porcelain insulators utilizing from local raw materials from developing countries. The raw materials used were feldspar, quartz/silica and kaolin. The chemical composition, mineralogy, and thermal properties of the raw materials were characterized using AAS, XRD, and TGA respectively. Different weight percentage combinations of the individual raw materials were investigated by the authors. Most of the results showed relatively acceptable porcelain insulators properties such as low water absorption, porosity, high insulation resistance, dielectric strength and bulk density. The paper showed that electric porcelain insulators with good properties can be produced from available local raw materials in some developing countries using appropriate formulations. However, for production of improved porcelain insulators properties, suggestions were made on the areas for future research.

Thermal and Mechanical Studies of Perlite Concrete Casing for Chimneys in Residential Buildings

Chimneys are structures designed to convey exhaust gases from heating devices to the outside of buildings. The materials from which they are made have a great impact on their fire safety, as well as on the safety of the whole building. As current trends in the construction industry are moving towards improving the environmental impact and fire safety, changes to building materials are constantly being introduced. This also applies to the development of chimney technology, as there is still a recognised need for new solutions when it comes to materials used in the production of chimney systems. This article presents the findings of tests carried out on a chimney made from innovative perlite concrete blocks. Four different perlite concrete blocks that differed in bulk densities were analysed. The obtained results were then compared with widely used leca (lightweight expanded clay aggregate) concrete blocks. The test results confirmed high insulation properties of the perlite concrete block, from which the innovative chimney casing was made. The fire safety level was maintained even in high temperatures that occur during soot fire (1000 °C). These properties were retained despite there being no additional insulation of the flue duct. Even though the thermal load decreased the compressive strength of the chimney blocks, they still displayed sufficient average strength of 4.03 MPa. Additionally, the test results confirmed the possibility of recovering heat from the chimney with the efficiency of 23–30%, which constitutes a considerable increase compared to chimneys made from leca concrete blocks.