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Reactivity assessment of aggregates : the role of chert crystallinity
Author(s)
Date Issued
2005-05
Date Available
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.
Sponsorship
Other funder
Other Sponsorship
Irish Cement
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
Subject – LCSH
Alkali-aggregate reactions
Chert
Aggregates (Building materials)--Expansion and contraction
Aggregates (Building materials)--Testing
Language
English
Status of Item
Peer reviewed
This item is made available under a Creative Commons License
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Name
13 Reactivity assessment of aggregates the role of chert crystallinity ACI Materials.pdf
Size
380.85 KB
Format
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