Report No. : GEO Report No. 354

Report Title : Feasibility Study on Use of Supplementary Cementitious Materials to Mitigate Alkali-silica Reaction in Concrete Made with Volcanic Aggregates (2022), 36 p.

Author : H.D. Wong & W.S.M. Tam

Abstract

Volcanic aggregates are rarely used in concrete production for public works projects in Hong Kong. The main reason is the risk of deleterious expansion due to alkali-silica reaction (ASR) in concrete.

Overseas studies have shown that the expansion due to alkali-silica reaction can be mitigated by using certain supplementary cementitious materials, such as ground granulated blastfurnace slag (GGBS), pulverized fly ash (PFA), and condensed silica fume (CSF). In the construction of a tall commercial building in Hong Kong, volcanic aggregates combined with PFA and CSF had been used in the construction of the mega central concrete cores.

The PWCL carried out an in-house study on the feasibility of using GGBS, PFA and CSF to mitigate the deleterious effects of ASR on concrete made with local volcanic aggregates from the Anderson Road Quarry and the Lam Tei Quarry. The laboratory investigation commenced in late 2014.

The study finds out that, by replacing the cement with adequate amount of GGBS, PFA and CSF, the 2-year expansion of the concrete prism due to the presence of ASR can be controlled within 0.02%, which is well below the 0.05% limit as stated in CS1:2010.

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