Comparison of expansions in the concrete prism and concrete microbar tests of an assorted suite of aggregates from several countries

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ConferenceProceedings of the 12th International Conference on Alkali-Aggregate Reaction in Concrete: 15 October 2004, Beijing, China
Pages251256; # of pages: 6
Subjecttest methods, concrete expansion, alkali-silica reactivity, alkali-carbonate reactivity; Concrete
AbstractThe usefulness of accelerated test methods for AAR, such as the mortar bar test ASTM C-1260, the various autoclave tests and the proposed Chinese concrete microbar test (RILEM AAR-5) depends on their being reasonable correlation between expansion in the concrete prism test and in the accelerated tests. Results of concrete prism tests run at 38°C are widely regarded as providing the best correlation with the performance of field concrete. The protocol for the concrete microbar test is similar to that of ASTM C 1260 except that the aggregate grading is 12.5 mm to 4.75 mm, the bar size is 40 x 40 x 160 mm and the mixture proportions are one part portland cement to one part aggregate. The concrete microbar test that was originally developed for the evaluation of alkali-carbonate reactive aggregates has been found to also be effective with alkali-silica reactive aggregates. A number of assorted aggregates from several countries were selected for evaluation in the concrete microbar test and in the concrete prism test (CSA A23.2-14A). The test results for siliceous limestones showed that there is good correlation between expansion in this test and in the concrete prism test. The proposed expansion limit is 0.09% at 30 days. No correlation was found between expansions in the two test methods for assorted siliceous aggregates including greywackes, sandstones, volcanic rocks, gravels and cataclastic rocks. However, aggregates in bars showing less than 0.04% expansion at 30 days were classed as innocuous in the concrete prism test. In the microbars, made with all the aggregates tested to date, expansion has been linear. This would permit estimation of the 30-day expansion by extrapolation from expansion at earlier ages. Opal exhibited no pessimum proportion in the concrete microbar test. Expansion was proportional to the percentage of opal added to an innocuous aggregate.
Publication date
AffiliationNRC Institute for Research in Construction; National Research Council Canada
Peer reviewedYes
NRC number47359
NPARC number20377398
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Record identifier389503d6-1ac1-401f-9b33-e6d198d55a84
Record created2012-07-24
Record modified2016-05-09
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