ISSN: 0149-6123
Page Count: 10

Limits of Application of the ASTM C 227⁴ Mortar Bar Test. Comparison with Two Other Standards on Alkali Aggregate Reactivity
Ranc, R
Manager, Quality and Products, Direction des Performances Cimentières, Lafarge Coppée,

Isabelle, H
Consultant, Corporate Technical Services, Lafarge Canada, Inc., Quebec

Yves Clément, J
Research engineer and senior research scientist, Lafarge Coppée Recherche,

Sorrentino, D
Research engineer and senior research scientist, Lafarge Coppée Recherche,

Abstract

Mortar bar expansion tests sometimes provide unreliable data concerning the potential reactivity of aggregates in an alkaline medium. The most widely used mortar bar test, known as the Test Method for Potential Alkali Reactivity of Cement-Aggregate Combinations (Mortar Bar Method) (ASTM C 227) is a case in point. The alkali-carbonate reaction, which is outside the scope of this standard, will not be discussed in this paper. The procedure related to the storage conditions and the leaching of the alkalies from the bars have been the subject of several recent papers. The investigation presented in this paper covers six deleteriously expansive coarse aggregates, which were correctly evaluated when tested in concrete prisms, but not in mortar bars. The Test Method for Potential Reactivity of Aggregates (Chemical Method) (ASTM C 289) has also been used but was not found to be reliable. Based on data developed from the above tests and a complete petrographic examination, it is concluded that reducing the particle size of the materials as required in the mortar bar test contributes to a decrease in expansion.

Keywords:
aggregates, alkali reaction, mortar bar tests, concrete prism test, comparative results, size reduction

Paper ID: CCA10564J
DOI: 10.1520/CCA10564J
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