Investigation on lithium migration for treating alkali-silica reaction affected concrete

Investigation on lithium migration for treating alkali-silica reaction affected concrete

Silva De Souza, L.M.
Polder, R.B.
Copuroglu, O.

Civil Engineering and Geosciences

Structural Engineering

2014-06-30

Alkali-silica reaction (ASR) is one of the major deterioration mechanisms that affect numerous concrete structures worldwide. During the reaction, hydroxyl and alkali (sodium and potassium ) ions react with certain siliceous compounds in the aggregate, forming a hygroscopic gel. The gel absorbs water from the cement paste and swells, possibly leading to deleterious expansion and cracking of the structure. Once ASR is detected in existing structures, there are no treatments to stop it and prolong their service life. Lithium is known to alter the reaction, as it binds to the alkali-silica gel and the latter is no longer expansive. Indeed, the use of lithium-based admixtures has been acknowledged as a preventive measure for over 50 years. In existing structures, nevertheless, the use of admixtures is no longer possible and lithium ions need to be transported into the cementitious matrix. Amongst other transport mechanisms, such as capillary absorption and diffusion, ionic migration is the most effective. In order for ionic migration to occur, power should be supplied between two electrodes, immersed in electrolytes. The reinforcement bar is often used as cathode and, therefore, attracts cations, such as lithium ions. Pore solution works as catholyte. The anolyte, on the other hand, should be a lithium compound solution. Although several studies have been conducted on the use of electric field to drive lithium ions into concrete, so far, there is no agreement on the conclusions. It is necessary to fully understand lithium migration into concrete before developing a possible treatment against ASR. This paper presents preliminary results on the investigation of the influence of different lithium compounds used as anolyte during migration through experimental testing.

alkali-silica reaction
repair
electrochemical method
migration

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NCF

Proceedings of the 1st Concrete Innovation Conference, CIC 2014, Oslo, Norway, June 11-13, 2014. Authors version

Institutional Repository

conference paper

(c) The authors