Technical Committee 190-SBJ
Building and construction sealants are an important economic factor. Nearly 60% of all gun-grade sealants are sold for building and construction applications. In 1996, this amount was of the order of 420,000 tonnes globally, at an installed cost of about $30 billion - this is the equivalent of sealing about 5-8 million kilometres (3-5 million miles) of joints each year. However, many of these joints fail prematurely. A survey of resealing activities carried out in the United Kingdom in 1990 revealed that 55% of building joints had failed within 10 years of service, and only 5% had lasted for more than 20 years. Studies conducted in Japan and Germany generated similar findings. The committee will identify, evaluate, develop and recommend methods for the prediction of service life of sealed building and construction joints. The study will focus on gun-grade (wet-applied) sealants and exclude pre-formed seals (gaskets, tapes). Some methodologies for predicting the service life of sealed joints have already been developed on a national basis (Japan, Canada), but a uniform, global approach does not exist. The intent of this RILEM committee is to developed a harmonised international approach
Terms of reference
The investigation will comprise a bibliographic survey of field performance data, development of theoretical concepts (methodologies) using computer modelling, and initial experimental verification of the proposed methodologies (including round-robin tests on some of the proposed test methods). The envisaged timeframe for completion of the work programme is 5-7 years. The committee will comprise about 12-15 active members and about 8-12 corresponding members. The affiliation of the members will be approximately 40-50% academic, 30-40% industry, and 10-20% practice. Provisional timetable: 2001-2003 Review and evaluation of current assessment methodologies 2003-2005 Development of new global methodology 2005/6 International Symposium, State-of-the-art report and publication of RTRs.
Detailed working programme
Separate Working Groups will be created for the execution of the work programme as follows: a) Study of factors causing degradation of sealed building and construction joints. Development of systematic knowledge on the type of degradation factors to be used in service life prediction models based on root fault analysis of known degradation mechanisms and resulting failure modes. Development of design guidelines and best application practices that incorporate above learning to achieve improved service life. b) Study of durability test methods for sealants and sealed joints. Development and verification of accelerated durability test methods that allow systematic assessment of the degradative damage caused by individually and synergistically acting degradation factors. c) Study of performance based methods of service-life prediction. Development of performance based methods of service life design based on models for degradation and environmental action.
The committee will build on the achievements of the previous RILEM committees TC139-DBS and 66-BJS. The committee will liase with ISO TC59/SC8 (Building - Jointing Products), ISO TC59/SC14 (Design Life of Buildings) and ASTM C-24 (Work Group on Sealant Durability Testing). Liaisons to other committees (CEN and national SDOs) focused on specific sealant applications (e.g. insulating glass, structural glazing) will be considered.
Recommendations by the TC are anticipated to result in improvements in how sealants are tested, specified and applied to maximise the service life of the sealed joint. Specific deliverables: · Proceedings of two symposia (2003, 2006) · State-of-the-art report (2006) · RTR on sealant durability test methods (2003-2006) · RTR Guidelines to the use of different service life prediction methods (2004-2006)
Group of users
- academics, testing laboratories, industrialists, practitioners, general public ... · Academics (universities, engineering colleges) · National testing and certification laboratories · Sealant industry specialists (developers, application engineers) · Practitioners (architects, specifiers, sealant applicators)
Specific use of the results
The deliverables will form the basis for the development of international (ISO) classification and test standards for building sealants. Use of a globally accepted methodology of service life prediction will reduce international trade barriers.