ABSTRACT
Radical Concrete Technology. Edited by R K Dhir and P C Hewlett. Published in 1996 by E & FN Spon, 2-6 Boundary Row, London SE1 8HN, UK. ISBN 0 419 21480 1. ABSTRACT. Test methods for quantifying chloride transport rates in concrete are reviewed and results from studies on fly ash concrete are presented. Fly ash imparts a significant improvement to the resistance of concrete to chloride ingress. However, much of this benefit is manifested at later ages, with significant reductions in diffusion occurring beyond the first year. Consequently, accelerated early-age tests are unlikely to provide a true measure of the service-life extension afforded by ash utilization. It is possible that the time-dependent diffusion effects could be accounted for by using suitable accelerated curing techniques for concrete containing fly ash (and similar materials). Most of the recent tests are further limited either by failure to provide a direct measure of chloride movement (ASTM C1202 and related tests) or by the rigorous application of mathematical relationships developed for ideal conditions not representative of chloride transport in concrete. However, such tests likely provide an index of the relative ease of chloride ingress and represent a considerable advance in performance testing for durability design. Keywords: Chloride, diffusion, fly ash, test methods Dr Michael Thomas is an Assistant Professor in Civil Engineering at the University of Toronto, Canada. His main research interests are related to concrete durability, the use of supplementary cementing materials and service life modelling. He is a member of a number of CSA, ACI and ASTM committees dealing with these issues. Dr Roderick Jones is a lecturer in construction materials in the Department of Civil Engineering and a member of staff of the Concrete Technology Unit at the University of Dundee, Scotland. His research interests include in the development of pozzolanic binders, particularly to enhance the durability of concrete. His current research work concerns chloride transportation processes and penetration rate estimation in concrete.
