Chloride content (DS/EN 1744-1 and NT Build 208)
Pelcon determine the chloride content of aggregates and in hardened concrete that has been exposed to chlorides.
Either of these analyses are based on the Volhard Titration with solutions of ammonium thiocyanate and silver nitrate.
Chloride content of aggregates
It is often of interest for a contractor to use local aggregate materials in the concrete mix design. This is especially relevant when the building site is located in a somewhat ‘deserted’ place – maybe even with a poor local infrastructure.
Use of aggregates with a high content of chloride can reduce the durability of the construction. Pelcon analyzes the chloride content of aggregates according to DS/EN 1744-1.
Test Method: DS/EN 1744-1
Chloride content of hardened concrete
In many cases it is of interest to know whether a reinforced concrete construction has a critical content of chlorides. By crushing small concrete samples and dissolving the dust in a solution of nitric acid it is possible to perform a Volhard titration and determine the chloride content. In some occasions it can be relevant to determine the chloride content in several levels (e.g. surface and reinforcement levels).
It is frequently desirable to make a chloride profile by analyzing more samples from various depths. Chloride profiles are essential for residual life estimation of concrete structures.
Please contact us for guidance in your specific project.
Test Method: NT Build 208
Chloride Migration according to NT Build 492
By exposing a sample of concrete to salt water (sodium chloride) under voltage it is possible to determine the chloride migration coefficient and thereby the concretes resistance against salt water.
This method offers good repeatability and reproducibility.
After the exposure of the specimen it is split in two halves and the section is sprayed with a solution of silver nitrate. This leads to a precipitation of grey-white silver chloride in the part of the section that was penetrated by chlorides during the test. The penetration depth is easily measured and based on the test parameters the non-steady-state migration coefficient (Dnssm) is calculated. Dnssm is stated in 10-12 m2/s in the final test report.