Towards a Global System for Preventing Alkali-Reactivity: The Continuing Work of RILEM TC 191-ARP


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Title: Towards a Global System for Preventing Alkali-Reactivity: The Continuing Work of RILEM TC 191-ARP

Author(s): I. Sims and P. J. Nixon

Publication: Special Publication

Volume: 212


Appears on pages(s): 475-489

Keywords: alkali-aggregate reaction (AAR); alkali-carbonate reactivity (ACR); alkali-silica reactivity (ASR); accelerated testing; aggregates concrete; alkali-reactivity; alkali release; carbonate aggregates; diagnosis; pterography; specification; testing

Date: 6/1/2003

Since 1988, RILEM has been seeking to establish universally applicable test methods for assessing the alkali-reactivity potential of aggregates. Technical committee TC 106 (1988-2000) published two expansion tests (AAR-2 & AAR-3), following international trials, and started to develop two further procedures (AAR-1 & AAR-4), together with an integrated assessment scheme (AAR-0). Successor committee TC 191-ARP (formed in 2000). comprising members from all parts of the world, is now working to finalise procedures AAR-1 & AAR-4 and additionally has a widened scope, to include carbonate aggregates (AAR-5) and also to seek international consistency in approaches to diagnosis and specification. This paper will review the latest progress of TC 191-ARP and, in particular, will outline the principles behind the petrographical examination procedure (AAR-I), report the findings of the international trial of AAR-4 and describe draft recommendations for assessing carbonate materials. The importance of systematic and reliable diagnosis of deterioration in existing structures will be stressed and the initial guidance of TC 191-ARP explained. Finally, the desirability of a global system for preventing damage to concrete from alkali-reactivity will be advocated and the proposals of TC 191-ARP reviewed. The authors are respectively Secretary and Chairman of TC 191-ARP and previously of TC 106.