Early-June ASTM committee meetings in St. Louis saw the launch of Subcommittee C09.50 Risk Management for Alkali Aggregate Reactions (AAR), targeting standards that will assist users to minimize or possibly prevent deleterious expansion in hydraulic cement mortar and concrete due to AAR
By Don Marsh, Editor
Early-June ASTM committee meetings in St. Louis saw the launch of Subcommittee C09.50 Risk Management for Alkali Aggregate Reactions (AAR), targeting standards that will assist users to minimize or possibly prevent deleterious expansion in hydraulic cement mortar and concrete due to AAR. As the subcommittee focuses on standards dealing specifically with preventing or minimizing AAR, test methods pertaining to reactive aggregate will remain under Subcommittee C09.26-Chemical Reactions.
The industry has been calling on ASTM to produce a guide or practice-type document dealing with alkali-silica and alkali-carbonate reaction, says Chryso Inc. Regional and Key Accounts Manager Steve Parker, C09.50 chairman and past C09.40- Ready Mixed chairman. Alkali-aggregate reactivity is, in part, time dependent. As we see more AAR and better understand the mechanisms behind it, there will be a continued and growing need for ASTM guidance to address potentially deleterious reactivity before concrete is batched.
The subcommittee will likely pursue separate documents on alkali-silica and alkali-carbonate conditions, he adds. In the interim, two task groups were designated during the first subcommittee gathering, which drew 65 attendees from the C01/09 meetings. The first task group is charged with assessing the potential use of American Association of State Highway and Transportation Officials, Federal Highway Administration and Canadian Standards Association AAR documents as a collective baseline for a C09.50 standard. The second will evaluate alternative methods or approaches to those of the AASHTO, FHWA and CSA documents. Chairing the document review and alternatives task groups are University of Illinois Civil and Environmental Engineering Professor Dr. Leslie Struble and U.S. Army Corps of Engineers Chemist Dr. Toy Poole, respectively. Subcommittee C09.50 will reconvene during December committee meetings in New Orleans.
Additional source: National Ready Mixed Concrete Association, Silver Spring, Md.