Incorporates the March 2026 Errata This method covers the procedures for determining acid-soluble chloride ions in concrete and concrete mix ingredients. The age of concrete, mortar, or hydrated portland cement at the time of sampling will have an effect on the acid-soluble chloride ion content. Therefore, unless early age studies are desired, it is recommended that the material be well cured and at least 28 days of age before sampling. This standard was formerly designated as provisional standard TP 55.