## 2 Problem Statement  
The process of reinforcement corrosion can be roughly divided into the phase until the reinforcement becomes depassivated, which is called the initiation phase, and the subsequent phase characterized by corrosion propagation. On the surface of the reinforcement, a microscopically thin oxide layer forms due to the alkalinity of the surrounding concrete, which keeps steel bars passive. The oxide layer is dissolved when the chloride threshold content is exceeded on the surface of the reinforcement, which leads to steel becoming depassivated. Once corrosion starts propagating, a deterioration caused by various mechanisms can be noticed, such as concrete cracking, delamination, loss of the steel-concrete bond, and loss of the reinforcement section. These mechanisms cause decay in the physical and mechanical properties of reinforcement and generate large repair and maintenance costs, with a severe impact on the durability and life-cycle performance [4]. Corrosion risks could be diminished by focusing on the preventive maintenance/repair of RC structures subjected to chloride ingress while the corrosion is still in its initiation phase. To be able to predict and control corrosion in its initiation phase, measurements of the chloride content should be performed. However, such measurements bear costs and associated uncertainties. Hence, the quantification of the value of information (VoI) can substantially contribute to showing if the tests and measurements of the chloride content in the phase of no visible damages would be cost effective. VoI analysis can be performed by taking into account four different events, namely the measurement of the chloride content, depassivation, damage, and repair. Herein, the event of measuring already initiated corrosion is not taken into account since the study focuses only on the VoI for the chloride content, i.e., the focus is set on the initiation phase in which there are no visible damages. All the stated events have a probability of occurrence and costs related to their outcomes. The costs of chloride measurements and concrete repair depend on numerous parameters, such as the methods of measurement, type of repair, market situation, etc. Thus, in this study, the costs of measurement and repairs are taken as relative to each other, resulting in a ratio of costs. This ratio is then easily translated to every particular situation, when a decision on performing chloride measurements has to be made. The first of the four stated events is the decision on performing the measurement (test) or not. If a measurement is performed, the results can indicate a need or no need for a repair, however, with a certain accuracy. The accuracy of the measurement results depends on the measuring technique, spatial variability, number of samples taken, etc. In the case that a measurement shows a state of depassivation and a repair is performed, it can be performed successfully or unsuccessfully. In the paper, the successful/unsuccessful event was observed only for the proactive repair. In cases where no measurements are performed or measurements indicated no need for repair, it is possible that the reinforcement is indeed already depassivated. Caused depassivation can, with a certain probability, trigger corrosion, which is herein considered as an undesirable event since it leads to damage. The described process can be depicted as a decision tree, as presented in Figure 1. As it can be seen, the decision tree results in nine possible outcomes, the costs of which are here marked as \(U_{i}\)Figure 1: Decision tree for determining the value of information for chloride measurements, where: (**a**) represents the events in the decision tree; (**b**) represents the probabilities of occurrence and associated costs. It is important to mention that the time component of the whole process was not taken into account.