1.1 This specification pertains to admixtures for masonry mortars. Admixtures are substances other than Specification C 270 prescribed materials of water, aggregate, and cementitious materials that are used to improve one or more of the recognized desirable properties of conventional masonry mortar.

1.2 This specification does not cover coloring pigments.

Information on coloring pigments can be found in Specification C 979.

1.3 This specification does not cover additives that are added to the cementitious materials during the manufacture of the cementitious materials.

1.4 Acceptance of an admixture is based on its performance in an admixed mortar. Acceptance of the admixed masonry mortar is based on attainment of performance either equivalent to that required for conventional mortar or improved performance of one or more indicated properties, while maintaining required performance levels for other properties.

1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

The testing laboratory performing the test methods referenced in this specification should be evaluated in accordance with Practice C 1093.