Effects of field stockpiling on leaching calcareous constituents from recycled concrete aggregate to be used as unbound base course/subbase material

Authors : Aiyoub ABBASPOUR, Burak TANYU

Pages : 1203-0

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Publication Date : 2020-12-31

Article Type : Research Paper

Abstract :Understanding the potential of recycled concrete aggregate insert ignore into journalissuearticles values(RCA); to precipitate calcareous constituents requires investigating the changes in solid and liquid chemistry of material throughout its service life including the stockpiling period. This study focuses on stockpiling freshly produced RCA in the field and monitoring the changes in concentrations of calcium and sulfur insert ignore into journalissuearticles values(as dominant ions);, as well as pH, total dissolved solids, and carbonate content for about two years. The results showed that the carbonate content of solid particles increases with time, which causes a noticeable reduction in total dissolved solids in the leachate. Aging also slightly decreases the pH; however, this decrease is very slow. The leached concentration of calcium showed a noticeable reduction with aging, indicating the effect of the formation of secondary carbonated minerals with lower solubility than calcium hydroxide and calcium-silicate-hydrate. On the contrary, sulfur insert ignore into journalissuearticles values(S); release insert ignore into journalissuearticles values(which is leached as sulfate ion); showed little effect of aging and carbonation process on the long-term leaching of S. The results obtained from the aging of the field RCA pile created in this study were also compared with the previously published laboratory aging of RCA and the comparison provided evidence supporting the field observations.
Keywords : RCA, leaching test, field aging, geosynthetic filter fabric, carbonation