Experimental investigation of the mechanisms by which LiNO{sub 3} is effective against ASR
- Departement de geologie et de genie geologique, Universite Laval, Quebec, QC, G1K 7P4 (Canada)
- Department of Civil Engineering, University of New Brunswick, Fredericton, NB, E3B 5A3 (Canada)
- Department of Civil Engineering, University of Texas, Austin, TX 78712 (United States)
Various series of experiments were carried out on cements pastes, concretes made with a variety of reactive aggregates, composite specimens made of cement paste and reactive aggregate particles, and a variety of reactive natural aggregates and mineral phases immersed in various Li-bearing solutions. The main objective was to determine which mechanisms(s) better explain(s) the effectiveness of LiNO{sub 3} against ASR and variations in this effectiveness as well with the type of reactive aggregate to counteract. The principal conclusions are the following: (1), the pH in the concrete pore solution does not significantly decrease in the presence of LiNO{sub 3}; (2), the concentration of silica in the pore solution is always low and not affected by the presence of LiNO{sub 3}, which does not support the mechanism relating to higher solubility of silica in the presence of lithium; (3), the only reaction product observed in the LiNO{sub 3}-bearing concretes looks like classical ASR gel and its abundance is proportional to concrete expansion, thus is likely expansive while likely containing lithium; this does not support the mechanisms relating to formation of a non or less expansive Si-Li crystalline product or amorphous gel; (4), early-formed reaction products coating the reactive silica grains or aggregate particles, which could act as a physical barrier against further chemical attack of silica, were not observed in the LiNO{sub 3}-bearing concretes, but only for a number of reactive materials after immersion in 1 N LiOH at 350 deg. C in the autoclave (also at 80 deg. C for obsidian); (5), higher chemical stability of silica due to another reason than pH reduction or early formation of a protective coating over the reactive phases, is the mechanism among those considered in this study that better explains the effectiveness of LiNO{sub 3} against ASR.
- OSTI ID:
- 21344754
- Journal Information:
- Cement and Concrete Research, Vol. 40, Issue 4; Conference: ICAAR 13:13. international conference on alkali-aggregate reaction in concrete, Trondheim (Norway), 16-20 Jun 2008; Other Information: DOI: 10.1016/j.cemconres.2009.09.022; PII: S0008-8846(09)00275-0; Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0008-8846
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AUTOCLAVES
CEMENTS
CONCRETES
EXPANSION
GELS
LITHIUM HYDROXIDES
LITHIUM NITRATES
PH VALUE
SILICA
SOLUBILITY
SOLUTIONS
STABILITY
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
ALKALI METAL COMPOUNDS
BUILDING MATERIALS
COLLOIDS
DISPERSIONS
HOMOGENEOUS MIXTURES
HYDROGEN COMPOUNDS
HYDROXIDES
LITHIUM COMPOUNDS
MATERIALS
MINERALS
MIXTURES
NITRATES
NITROGEN COMPOUNDS
OXIDE MINERALS
OXYGEN COMPOUNDS
TEMPERATURE RANGE