7 APPLICATION OF KRAFT AND ACRYLIC FIBRES TO REPLACE ASBESTOS IN COMPOSITE CEMENT SHEETS ESHMAIEL GANJIAN 1 , MORTEZA KHORAMI 2 & HOMAYOON SADEGHI+POUYA 1 *1 Coventry University, Department of the Built Environment, Faculty of Engineering & Computing, Sir John Laing Building, Coventry, CV1 5FB. *2 Building & Housing Research Centre/Eslamshahr Islamic Azad University, Tehran, Iran, PO Box 131458 1696. ABSTRACT This work presents a characterisation of Kraft and Acrylic fibres in formulations of fibre cement slurries, seeking the replacement for asbestos as fibre in cement+based products. All these materials can be easily provided in Iran and other developing countries which cannot afford the new special cellulose and polymeric technologies exclusive to developed countries. The interest in finding materials that substitute asbestos is due to controversies concerning the use of this material and associated health problems in developing countries. The chemical, physical and mechanical properties of fibres were determined followed by the flexural strength and modulus of elasticity of fibre cement specimens. The results indicate that the fibre contents and types affect the flexural behaviour and fracture mechanism of composite sheets significantly. The mix design with optimum amount of Kraft and Acrylic fibres found in this investigation satisfies Class 2 classification of the EN 12497 standard and is a feasible alternative for some asbestos cement sheet applications. KEYWORDS Kraft fibres; Acrylic fibres; Composite cement products; Cement sheets; Asbestos replacement. INTRODUCTION Asbestos is the name given to a group of fibrous hydrous silicates which not only have outstanding mechanical and physical properties but also have excellent durability against environmental conditions, stable in high pH range and high thermal coefficient. Because of its excellent characteristics, it has been used in different applications such as acoustic insulator, thermal insulation, fire proofing and other construction materials (Virta, 2003). Because of its easy and inexpensive processing as well as other characteristics, during the last century it was used as a building material with various forms and styles to suit different needs. Asbestos Composite Cement Board (ACCB) has been one of the major applications of asbestos fibres in construction, so that at present there are many buildings around the world having ACCB as roofing tiles or wall boards. Despite the international ban on the usage of asbestos, there are ten Cement Composite Boards factories in Iran and they all use asbestos in their products. The annual amount of asbestos used has increased since 1985 (20,000 tonnes) and is estimated to be 76,000 tonnes in 2003 (Vitra, 2006) and 64,300 tonnes in 2004 (BWI site, 2008). The available statistics show that the production of flat and corrugated cement boards is in excess of 30,000,000 m 2 and 4000 km length of composite cement pipes. Also according to the annual report of the Ministry of Health, the number of deaths due to asbestos related diseases is about 4000 per year. The design of a durable and low+cost asbestos+free composite cement sheet is a technological challenge in developing countries. As increasing concerns are being associated with chrysotile fibres, new research is now expected for the adaptation of available raw+materials and production systems to fit the consumer requirements at each particular application area (Giannasi, 1997 and Harrison, 1999).