Name: Simon Fjendbo

Title of your project: Application of marine field data for prediction of chloride ingress in concrete

Project description:

The focus of this study was to test and further develop the basis for application of chloride ingress models for service life design and reassessment of marine exposed reinforced concrete structures.

The topic was approached by conducting an evaluation of which chloride data to use and how to use them for chloride ingress predictions by analyzing a) microstructural changes in the concretes and their impact and b) the assumptions made if correcting for paste fraction. By comparing chloride profiles combined with petrographic analysis of tidal and submerged concrete after ten years of marine exposure, supplemented with moisture and portlandite profiles of the submerged exposed concrete and earlier data on microstructure and chloride ingress, the relationship between chloride profiles and microstructural changes was investigated.

The square root method was proposed (based on earlier observations of a square root time dependency of the the depth of a given chloride content) and compared to selected engineering models by evaluating the ability to predict data achieved after ten years of submerged exposure at the Fehmarn Belt Exposure Site based on data achieved up to five years of exposure.

The work was undertaken by Simon Fjendbo, Technological Institute, Denmark, as Industrial PhD student with Professor Mette R. Geiker, NTNU, as Main Supervisor and Professor Klaartje De Weerdt, NTNU, and PhD. Henrik E. Sørensen, Technological Institute, Denmark as Co-supervisors.

Funding: Danish Technological Institute through the contract “E5 Field exposure and monitoring to extend the service life of infrastructure”(translation from Danish) granted by the Danish Ministry of Higher Education and Science (Link).

Date of start of Phd: October 2018