ASTM C1293-20a PDF Download

ASTM C1293-20a is a standard test method that determines the length change of concrete due to alkali-silica reaction. This chemical interaction occurs between certain siliceous constituents of concrete aggregates and hydroxyl ions, which are primarily controlled by the concentration of sodium and potassium in the concrete. The purpose of this test method is to evaluate the potential of an aggregate or a combination of aggregate with pozzolan or slag to expand detrimentally due to alkali-silica reactivity.

When testing an aggregate with pozzolan or slag, the results obtained from this test method can be used to establish minimum amounts of the specific pozzolan or slag required to prevent destructive expansion. The variability in lithology of materials from a given source, such as sand, gravel, or rock formations, should be taken into consideration when selecting samples for testing.

This test method is applicable for evaluating the behavior of aggregates in portland cement concrete with an alkali content of 5.25 kg/m3 or in concrete containing reduced alkali content due to the presence of pozzolan or slag. It assesses the potential for deleterious expansion caused by alkali-silica reaction in both coarse and fine aggregates under laboratory curing conditions, which may differ from field conditions. Therefore, the actual performance in the field may not be duplicated due to various factors.

The results of tests conducted according to this test method should be considered when making decisions regarding precautions against excessive expansion due to alkali-silica reaction. Interpretation of test results can be done by referring to Guide C1778. Petrographic examination of the concrete prisms and identification of known reactive constituents and products of alkali-silica reactivity using Practice C856/C856M can confirm the presence of alkali-silica reaction. Compliance with specific material specifications, such as Specification C618, C989/C989M, or C1240, is necessary for the general suitability of pozzolans or slag for use in concrete.