Study on the Accuracy of Chloride Determination Methods and Their Predictions

EasyChair Preprint 4044

Abstract

At ASFiNAG, most structures are made of reinforced concrete. In Austria strong winters are obligatory. Therefore, de-icing measures with salt are used for thawing. These substances contain chlorides, that ingress into the concrete and lead to degradation.

For condition assessment and service life prediction of existing road structures the determination of a reliable chloride content is key. The article presents the results of the chloride content of reinforced concrete obtained by two methods. One is the conventional Cl-determination described in standards. The other is the LA-ICP-MS (Laser Ablation Inductively Coupled Plasma Mass Spectrometry) method, which is a fast, reliable, accurate and high-resolution analysis method. This method allows the determination of the chloride content as a fraction of cement and additionally distinguishes between the aggregate and the cement phase. The profiles were determined densely at steps of 3 mm in depth.

Regressions with different boundary conditions were used to fit the obtained data according to Fick’s 2nd law. For comparison and prediction purposes, the corresponding convection depth as well as the chloride diffusion coefficients were determined. These parameters, as well as the fluctuations of chloride profiles for one year deliver important insights for assessment and prediction.

Significant differences were observed in the results obtained by the applied analysis methods. The study addresses the origins of these differences and shows the variances when it comes to prediction of remaining service life. The results are compared and discussed to show the complex nature and sensitivity of the derived input parameters. These results show on one hand the importance for an accurate chloride analysis (LA-ICP-MS) and gives hints for an improved assessment of structures.

Keyphrases: LA-ICP-MS, Service life prediction, chloride content, existing structures

@booklet{EasyChair:4044,
  author    = {Fritz Binder and Stefan L. Burtscher and Alfred Strauss},
  title     = {Study on the Accuracy of Chloride Determination Methods and Their Predictions},
  howpublished = {EasyChair Preprint 4044},
  year      = {EasyChair, 2020}}