ASTM C1218

Full Name

ASTM C1218 – Standard Test Method for Water-Soluble Chloride in Mortar and Concrete


ASTM C1218 is a standard test method used to determine the water-soluble chloride content in mortar and concrete. This is important because water-soluble chlorides can initiate or accelerate the corrosion of embedded metals, such as steel reinforcement, in concrete structures.

The scope of ASTM C1218 includes:

  • Sampling: outlining procedures for obtaining representative samples of mortar or concrete for chloride analysis.
  • Sample preparation: detailing the steps involved in preparing the samples for analysis, including drying, pulverizing, and extraction with water.
  • Chloride determination: describing the method for determining the concentration of water-soluble chloride in the prepared samples, typically using a titration or other analytical techniques.
  • Interferences: addressing potential interferences, such as sulfides from blast-furnace slag aggregates, and outlining procedures to mitigate their effects on the results.

Key points to note about ASTM C1218:

  • Water-soluble vs. total chloride: this test method specifically measures water-soluble chloride, which is the portion of chloride ions that are readily available to participate in corrosion reactions. It does not measure the total chloride content, which may include chloride ions that are chemically bound within the cement matrix.
  • Time-dependent results: the water-soluble chloride content can vary over time due to factors like chloride ingress, leaching, or binding. Therefore, it’s important to consider the age and exposure conditions of the concrete when interpreting the results.
  • Test conditions: the test conditions can affect the water-soluble chloride determination. Therefore, caution should be exercised when comparing results obtained using different test methods or conditions.

Overall, ASTM C1218 provides a standardized and reliable method for measuring water-soluble chloride in mortar and concrete, which is crucial for assessing the risk of corrosion in reinforced concrete structures and making informed decisions about maintenance and repair.

ASTM C1218 Accredited Laboratory

Applied Testing & Geosciences, LLC is accredited for performing tests using the ASTM C1218 standard.

Contact us for more information.



water-soluble chloride; mortar; concrete; sampling; analysis; titration; extraction; corrosion; aggregates; sulfides