14. Brick and other ceramic products
Clay has been used in a wide range of ceramic products for thousands of years and continues to be a major component in most ceramic bodies today. Fiebinger (1997) states that the annual worldwide production of clay is nearly 400 million tonnes. In the top 50 ranking of extracted minerals and materials, clay is placed 8th with respect to quantity, and 19th in terms of value. Over 90% of the annual tonnage is utilized in the heavy or structural clay sector, with the remainder (predominantly ball clays and plastic clays) being used for higher quality or fine ceramic products. The value of the worldwide ceramic production (of all varieties) was estimated at US$ 113 billion in 2000 (Reh 2000). From 1991 to 1999, growth was significant in the advanced ceramics, tile and sanitaryware sectors, but less so in structural ceramics and refractory products, as detailed below:
wall and floor tiles; 70% growth with US$ 14 billion turnover in 1999;
advanced ceramics (including the carbon and graphite sector); 63% growth with US$ 40 billion turnover in 1999;
sanitaryware; 50% growth with US$ 12 billion turnover in 1999;
structural ceramic sector (bricks, roofing tiles, pipes); 17.5% growth with US$ 23 billion turnover in 1999;
refractory products; <10% growth with US$ 12 billion turnover in 1999.
The technical definition of a ceramic product is ‘a product that is composed of polycrystalline, inorganic and non-metallic materials that have been subjected to a temperature of 540°C or more during manufacture or use’ (O’Bannon 1984). In spite of the availability of modern, alternative products manufactured from plastic, steel, paper, glass-fibre/resin composites, borosilicate glass etc., the demand for ceramic products in all sectors remains relatively strong. This chapter describes how the chemical, physical and ceramic properties of the clay components have a predominant influence on the characteristics of both the unfired and fired product, and also considers the role and importance of the other body materials.
Figures & Tables
Concluding the trilogy on geological materials in construction by specially convened Geological Society working parties, this authoritative volume reviews many uses of clays, ranginf from simple fills to manufactured products. Comprehensive and international coverage is achieved by an expert team, including geologists, engineers and architects, who met over six years to produce the book. Packed with information prepared for a wide readership, this unique handbook is also copiously illustrated. The volume is dedicated to the memory of Professor Sir Alec Skempton.
Various definitions of ‘clay’ are explored. Clay mineralogy is described, plust the geological formation of clay deposits and their fundamental materials properties. World and British clay deposits are reviewed. New compositional data are provided for clay informations throughout the British stratigraphic column. Investigate techniques and interpretation are considered, ranging from site exploration to laboratory asessment of composition and engineering performance.
Major civil engineering applications are addressed, including earthworks, earthmoving and specialized roles utilizing clays. Traditional earthen building is included and shown to dominate construction in places. Clay-based construction materials are detailed, including bricks, ceramics and cements. The volume also includes a comprehensive glossary.