Building materials for a sustainable future – cement

Abstract

Concrete is second only to water in terms of the most consumed substances on earth. Cement is the "glue" which holds concrete together and it is therefore a construction material which is produced and consumed in huge quantities worldwide. Global cement production is about 2.8 billion tonnes per year (WBCSD, 2011a) and growing at an annual rate of close to 4%, largely driven by demand from developing countries. The South African cement industry produces about 17.5 million tonnes of cement per annum. This is about 0.6% of current annual global production and constitutes about 16.5% (CIDB, 2007) of the market share of the major South African construction materials. The relative contributions of the traditional materials to building cost in South Africa follow the order: 1. cement and reinforced concrete (35%), of which 50% is cement, 2. plain carbon steel products (structural steel, tiles, flat and profiled sheets, door frames, window frames and garage doors) (23%), 3. bricks and blocks (12%), 4. Timber and wood (10%), 5. Tiles and sanitary ware (9%), 6. plastics (4%), 7.non-ferrous metals (4%), 8. glass (3%). Four companies account for more than 80% of cement produced in South Africa. These are AfriSam South Africa (Pty) Ltd, Natal Portland Cement (NPC) Cimpor, Lafarge South Africa and Pretoria Portland Cement (PPC). Sephaku Cement is the new kid on the block.