Mitigating Alkali Silica Reaction in Recycled Concrete


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Title: Mitigating Alkali Silica Reaction in Recycled Concrete

Author(s): H. C. Scott IV and D. L. Gress

Publication: Special Publication

Volume: 219


Appears on pages(s): 61-76

Keywords: alkali silica reaction (ASR); concrete recycling; durability; fly ash; ground granulated blast furnace slag; lithium nitrate; recycled concrete aggregate; silica fume

Date: 3/1/2004

This study investigated the reactivity of concrete containing recycled concrete aggregates (RCA) that had shown distress due to alkali silica reaction (ASR). The investigation evaluated several mitigation techniques to control ASR in concrete containing potentially reactive RCA. Mitigation work was done with three different aggregate types; an igneous fine-grained quartzite aggregate locally called blue rock, a non-reactive limestone, and RCA containing blue rock aggregate. These aggregates were used to investigate various mitigation techniques to prevent ASR from occurring in concrete containing RCA. The mitigation strategies include the use of class F fly ash, ground granulated blast furnace slag (GGBFS), lithium nitrate, silica fume blended cement and low alkali cement. These materials were incorporated into concrete mixes by cement substitution and direct application. These mitigation strategies showed potential in controlling ASR distress in RCA concrete. Mortar bars and concrete prisms were used to investigate the mitigation strategies by following standard and modified versions of ASTM C 1260 and ASTM C 1293 specifications to evaluate expansion caused by ASR. The modified versions of ASTM C 1260 were found effective in evaluating potential ASR expansion using conventional aggregates.