INDUSTRIAL WASTES AND NATURAL SUBSTANCES FOR IMPROVING ELECTRICAL EARTHING SYSTEMS

摘要

Performance of deep driven Galvanized Iron (GI) electrodes encased in several backfill materials, which are freely available as industrial waste or at a low cost in many countries, were investigated over a period of 2-3 years. The best performing material, metal oxide powder (a waste product of the steel industry), was tested against several commercially available and traditionally used backfill materials. It was found that these industrial wastes reach the level of performance of commercially available backfill materials after several months. It was also found that the percentage of material erosion of GI due to corrosion in the presence of metal oxide powder is less than 1% after more than two years in contact. Lime and coke breeze also show good performance with respect to corrosion while commercially available natural Bentonite performs the best. Sodium Chloride, a backfill material that is widely used in South Asia, gave a highly undesirable outcome; the earth resistance of the relevant electrode fluctuates in a wide range of values and the corrosive effects are unacceptably high. It is also shown that the earth resistance of electrodes with sodium chloride as backfill material is 100% greater than the value predicted by theoretical formula available in the literature.