ABSTRACT
An integral concept of specification for durability in structures is that the material properties should meet the performance requirements over a defined life. This concept has been in the background in standards and codes of practice for over 50 years. For example in the United Kingdom, Code of Practice CP3, Chapter IX on durability (Council for Codes of Practice for Buildings 1950) included definitions of both the ‘designed life’ and the ‘satisfactory life’. More recently British Standard BS 7543 (1992) has been published to cover the durability of buildings and their elements. Significantly, in the quest to provide a rational basis for achieving design life, a joint RILEM/CIB group developed a systematic methodology for service life prediction (Masters and Brandt 1989). This has been adopted for standardisation by the International Standards Organisation (1998) as ISO 15686 ‘Service Life Planning of Buildings’. The RILEM/CIB methodology built on earlier work from Sweden (Sentler 1983) and in the Netherlands (Siemes et al. 1985). This was further studied and a clearer focus on the way forward was provided by the publication of RILEM Report 14 (Sarja and Vesikari 1996) and CEB Bulletin 238 (Schiessl et al. 1997). Meanwhile a significant impetus to the development of the tools necessary to apply the service life principles was provided through a European project ‘DuraCrete’ (Probability Performance Based Design of Concrete Structures). Although the stage has yet to be reached whereby codes and standards will fully embrace the concepts, degradation models of a deterministic nature have been used on major infrastructure projects in Denmark and a stochastic model was used to document the required service life in a contract in the Netherlands.
