ABSTRACT
Most industrial processes and practices are specifically aimed at producing a primary product or products which can be utilised with or without beneficiation to practical benefit. Such products may be material oriented, such as steel, or service related, such as electricity. In general, besides the primary product, secondary products or by-products are produced. In many respects these by-products are often considered as waste products. It may be said that a waste product is a material which we have not had the imagination, ability or time to put into productive use. Engineering applications of these materials are of increasing interest from the point of view of waste utilisation as well as the economics of development and construction.
