Title: Aggregate Passivation: Lithium Hydroxide Aggregate Treatment to Suppress Alkali-Silica Reaction

Author(s): Craig W. Hargis, Maria C. G. Juenger, and Paulo J. M. Monteiro

Publication: Materials Journal

Volume: 110

Issue: 5

Appears on pages(s): 567-576

Keywords: aggregate; alkali-aggregate reaction; durability; expansion; lithium compounds

DOI: 10.14359/51685908

Date: 9/1/2013

Abstract:
Alkali-silica reaction (ASR) continues to be a concrete durability problem despite the many physical and chemical mitigation techniques known to successfully prevent it. The research presented herein tested a new method to limit ASR: aggregate passivation. A lithium silicate layer was created on reactive natural siliceous aggregate surfaces by treating the aggregates in a lithium hydroxide solution prior to use. A 4 M LiOH treatment was found to be superior to a 2 M LiOH treatment in producing a lithium silicate passivation layer and in reducing expansion due to ASR. The use of passivated aggregates greatly reduced expansion in accelerated mortar bar tests compared to nonpassivated aggregates and lithium-based admixtures.