Service life predictions and decision support for design and maintenance of concrete structures

Collaborations: Norwegian Public Roads Administration, ASFINAG

Background

When inspecting and assessing existing reinforced concrete structures in chloride exposure environments, decisions have to be taken about preventive and repair interventions to ensure the durability. Often, existing concrete structures already contain elevated levels of chloride in the cover concrete, but do not yet show corrosion damage. The question is: How much time is left until corrosion starts? Does the structure need immediate repair or can we wait another 10-20 years?
Standards do not offer a basis to answer these questions. Thus, it is generally difficult for public owners to base their maintenance planning on sound assessments and predictions of the future corrosion risk.
However, having in mind the increasing number of ageing structures that potentially need repair, it is important to have a scientifically sound basis for the prioritization of repair and maintenance works of different structures.

Aims and objectives

The aim of this project is to enable knowledge-based decision taking for the planning of maintenance works. This is achieved through making predictions for specific structures with respect to their future corrosion risk.

Methodology

We measure the critical chloride content for specific structures by taking samples from the structure and testing them in the laboratory (external pageLink to the "ETH method"). Together with an assessment and evaluation of the related chloride profiles determined in the concrete cover, the chloride ingress over time can be calculated. By means of a probabilistic model, the future corrosion risk is predicted.