Technical
The determination of the chloride ion concentration in concrete is essential in assessing the need for maintenance on, for example, bridge decks and parking structures. The test can also be used to ensure that materials used in new construction are free from potentially harmful chloride ion levels.

With this method, the concentration of acid soluble chlorides is measured. In most cases, this is equivalent to total chloride concentration.

A sample of powder is obtained by drilling and careful quartering. Then an accurately weighed 3 gr. (0.1 oz) sample is dissolved in 20 ml (0.67 fl. oz.) of extraction liquid which consists of a precise, measured concentra-tion of acid. For sampling wet concrete a 3 gr. (0.1 oz.) sample of mortar (i.e. without coarse aggregate) is used.

The chloride ions react with the acid of the extraction liquid in an elec-trochemical reaction. An electrode, with integral temperature sensor, is inserted into the liquid and the electrochemical reaction measured. A uniquely designed instrument converts the voltage generated by the chloride concentration. The instrument automatically applies the temperature correction and it shows the chloride concentration on a LCD display in either lbs. per cu. yd. or percentage by weight.

Once the sample is obtained, test results can be determined and read in less than five minutes.

To avoid contamination, the electrode should be thoroughly washed with deionized water after each test.

Replacement packs, containing twelve bottles of extraction liquid, each for one time use, are available. Five calibration liquids each with known concentrations are supplied with each pack.

These liquids are used to establish the calibration curve, and to check that the system is functioning correctly. Calibration is not required for each use. The calibration liquids are colored to avoid confusion between them and with the extraction liquid.

All equipment necessary to complete the chloride test is supplied in a standard size carrying case.