4.1 Two types of alkali reactivity of aggregates have been described in the literature: the alkali-silica reaction involving certain siliceous rocks, minerals, and artificial glasses (1),3 and the alkali-carbonate reaction involving dolomite in certain calcitic dolomites and dolomitic limestones (2). This test method is not recommended as a means to detect combinations susceptible to expansion due to alkali-silica reaction since it was not evaluated for this use in the work reported by Buck (2). This test method is not applicable to aggregates that do not contain or consist of carbonate rock (see Descriptive Nomenclature C294).

4.2 This test method contains two methods. Method A is used to evaluate the susceptibility of a coarse aggregate to alkali-carbonate reaction. Method B is to evaluate the behavior of specific combinations of concrete-making materials to be used in concrete construction. However, provisions are made for the use of substitute materials when required. This test method assesses the potential for expansion of concrete caused by alkali-carbonate rock reaction from tests performed under prescribed laboratory curing conditions that will probably differ from field conditions. Thus, actual field performance will not be duplicated due to differences in wetting and drying, temperature, other factors, or combinations of these.

4.3 Use of this test method is of particular value when samples of aggregate from a source have been determined to contain constituents that are regarded as capable of participation in a potentially deleterious alkali-carbonate rock reaction either by petrographic examination, Guide C295/C295M, by the rock cylinder test, Test Method C586, by service record; or by a combination of these.

4.4 Results of tests conducted as described herein should form a part of the basis for a decision as to whether or not the aggregate under test can be used in portland cement concrete construction. Interpretation of results can be found in Guide C1778.

4.5 At the conclusion of the test it may be useful to conduct petrographic examination on the concrete following Practice C856/C856M and the aggregate following Guide C295/C295M to confirm that the aggregate causing expansive behaviour of the concrete, if any, is comparable to the petrography and chemistry of known deleteriously expansive alkali-carbonate reactive rocks. It is important to check the presence of potentially reactive silica that may not necessarily be visible at the scale of conventional transmitted light optical microscopy examination.

4.6 The research, evaluation, and precision and bias statement for this test method were done on crushed quarried carbonate coarse aggregate (3). Therefore, the results of evaluating alkali-carbonate reactive expansion of manufactured fine aggregate or natural sand containing crusher screenings derived from quarried carbonate rocks is unknown. Further, the applicability of this test to gravels containing carbonate rocks suspected of being alkali-carbonate reactive is unknown and as far as is known has not been evaluated.

1.1 This test method covers the determination, by measurement of length change of concrete prisms, the susceptibility of a coarse aggregate or cementitious materials aggregate combinations to expansive alkali-carbonate reaction involving hydroxide ions associated with alkalies (sodium and potassium) and certain calcitic dolomites and dolomitic limestones.

1.2 Results of tests conducted as described herein should form a part of the basis for a decision as to whether or not the coarse aggregate or specific combinations of concrete-making materials under test can be used in portland cement concrete construction. Interpretation of results can be found in Guide C1778.

1.3 The text of this standard refers to notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.

1.4 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard. When combined standards are cited, the selection of measurement system is at the user's discretion subject to the requirements of the referenced standard.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.