AASHTO T 260-21 covers procedures for the determination of the acid-soluble chloride ion content or the water-soluble chloride ion content of aggregates, portland cement, mortar, or concrete. The total amount of chloride is usually equal to the acid-soluble chloride. However, organic additives or minerals that contain acid-insoluble chloride may be present in concrete and concrete raw materials. these constituents may become acid soluble during long-term exposure to the alkaline environment in concrete or mortar. The age of concrete mortar or hydrated portland cement at the time of sampling will have an affect on the water-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.