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Automated Chloride Determination in Concrete
A Fully Automated Procedure Including Sample Preparation
This application note (download below) gives the detailed method and procedure tips for automated chloride determination in concrete by potentiometric titration.The method is based on the standard SN EN 14629:2007 and includes fully automated digestion of the concrete sample – the sample only needs to be weighed manually.
Background
High amounts of chloride ions in concrete cause the deterioration of concrete structures. This happens because chloride compounds induce the corrosion of the steel reinforcement, which in turn damages the surrounding concrete. Chlorides can be incorporated in the concrete mix through chloride-containing admixtures, contaminated aggregates or from mixing water. Solutions with chloride ions (i.e. for example, sea water or dissolved de-icing salt) can also penetrate concrete that is already set, making the chloride content increase with time.
For safety reasons, the amount of chloride in reinforced concrete is limited by official standards that vary between different countries. An efficient and accurate method for the determination of chloride ions is thus required. The concentration of chloride ions can be measured by precipitation titration with silver nitrate as titrant since the reaction between chloride and silver ions leads to an insoluble salt.
Reaction:
Cl-(aq.) + Ag+(aq.) → AgCl(s.)
For more information about titration, including precipitation titration, see our Titration Fundamentals guide.
Video: Experimental procedure for automated chloride determination in concrete
