Standard Test Method for Determining the Potential Alkali-Silica Reactivity of Combinations of Cementitious Materials and Aggregate (Accelerated Mortar-Bar Method)

Importancia y uso:

4.1 This test method provides a means for evaluating the ability of pozzolans and slag cement to control deleterious internal expansion due to alkali-silica reaction when used with an aggregate intended for use in concrete. It is based on the Accelerated Test Method developed at the National Building Research Institute (NBRI) in the Republic of South Africa (1-4).3

4.2 This test method has been developed for evaluating combinations of certain cementitious materials with a single aggregate source in a mortar of standard proportions. It yields an empirical result, which is utilized to compare to criteria within some specifications to accept or reject the combination of materials being evaluated for a particular application. Currently this method has no standard procedure for testing fine and coarse aggregates proposed for use in concrete together in a single batch of mortar, nor for varying the proportions of the constituent materials of the mortar beyond the relative proportions of the individual cementitious material constituents to each other, as the significance of these practices have not been determined nor have appropriate limits been established for evaluating the results of tests conducted using these modifications.

4.3 Different levels of pozzolan and slag cement may require testing to determine the amount required to reduce expansion to an acceptable level. Pozzolans and ground granulated blast-furnace slag may be tested separately or in combination.

4.4 It is recommended to test the same aggregate without pozzolans and slag cement using Test Method C1260.

4.5 Results of tests conducted as described herein shall form a part of the basis for determining the precautions that shall be taken against excessive expansion due to alkali-silica reaction. Refer to Guide C1778 for the interpretation of the test results from Test Method C1567.

4.6 This test method is not suitable for evaluating high-alkali pozzolans and slag cements, including if these materials are constituents of a blended hydraulic cement. Coal ash or ground glass pozzolan with greater than 4.0% Na₂O_eq, and slag cement or silica fume with greater than 1.0% Na₂O_eq are considered high-alkali materials. Refer to Guide C1778 for recommended performance testing approaches for these materials.

Subcomité:

C09.50

Referida por:

C1709-22, C1567-25, C1778-23, C1866_C1866M-22

Volúmen:

04.02

Número ICS:

91.100.30 (Concrete and concrete products)

Palabras clave:

aggregate; alkali-silica reactivity; length change; mortar; pozzolans; slag cement; sodium hydroxide;