Reactivity assessment of aggregates : the role of chert crystallinity

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Title: Reactivity assessment of aggregates : the role of chert crystallinity
Authors: McNally, Ciaran
Richardson, Mark G.
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Date: May-2005
Online since: 2010-10-11T13:45:32Z
Abstract: A systematic assessment scheme for determining the alkali reactivity of aggregates has been developed for international use. Expansion tests were conducted on Irish aggregates. Aggregates were subjected to a sequence of tests for alkali reactivity: petrographic examination and mortar bar and concrete prism expansion testing. No cases of damaging alkali-silica reaction have been identified to date in Ireland despite the presence of chert in significant commercial sources. Chert-bearing Irish aggregates performed poorly in expansion tests despite an exemplary service record. Chert crystallinity was examined through domain size and quartz crystallinity index. The crystallinity study helped explain the apparently anomalous behavior of the aggregates in tests. A preliminary study of the effect of alkali loading provided confirming evidence. It is suggested that enhanced crystallinity raises the alkali threshold value for reaction to one intermediate between that experienced in practice and in tests.
Funding Details: Other funder
Type of material: Journal Article
Journal: ACI Materials Journal
Volume: 102
Issue: 3
Start page: 163
End page: 169
Copyright (published version): 2005, American Concrete Institute
Keywords: Alkali-aggregate reactionChertExpansion
Subject LCSH: Alkali-aggregate reactions
Aggregates (Building materials)--Expansion and contraction
Aggregates (Building materials)--Testing
Language: en
Status of Item: Peer reviewed
Appears in Collections:Critical Infrastructure Group Research Collection
Civil Engineering Research Collection

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