Report on the Diagnosis, Prognosis, and Mitigation of Alkali- Silica Reaction (ASR) in Transportation Structures
Primary Topic: Materials-Concrete
Description: Alkali–aggregate reaction (AAR) is only one of the many factors that might be fully or partly responsible for the deterioration and premature loss in serviceability of concrete infrastructure. Two types of AAR reaction are currently recognized depending on the nature of the reactive mineral; alkalisilica reaction (ASR) involves various types of reactive silica (SiO2) minerals and alkali–carbonate reaction (ACR) involves certain types of dolomitic rocks (CaMg(CO3)2). Both types of reaction can result in expansion and cracking of concrete elements, leading to a reduction in the service life of concrete structures.
This document described an approach for the diagnosis and prognosis of alkali–aggregate reactivity in transportation structures. A preliminary investigation program is first proposed to allow for the early detection of ASR, followed by an assessment (diagnosis) of ASR completed by a sampling program and petrographic examination of a limited number of cores collected from selected structural members. In the case of structures showing evidence of ASR that justifies further investigations, this report also provides an integrated approach involving the quantification of the contribution of critical parameters with regards to ASR.
FHWA Publication Number: FHWA-HIF-09-004
Publication Year: 2010