This specification covers materials proposed for use as air-entraining admixtures to be added to concrete mixtures in the field. The air-entraining admixture shall conform to the requirements such as initial and final time of setting, compressive strength, flexural strength, and length change (maximum shrinkage). Samples shall either be a grab sample (one obtained in a single operation) or a composite sample (one obtained by combining three or more grab samples). For the purpose of this specification, it is recognized that samples shall be taken for quality tests and uniformity tests.