## 5 Repair Methods  
In the Model Code 2010 [9], the term conservation embraces all activities aimed at maintaining or returning a structure to a state that satisfies the defined performance requirements. This includes activities, such as maintenance, repair, rehabilitation, retrofitting, replacement, etc. Furthermore, two different conservation objectives are distinguished:  
* Conservation activities with the intention to enable a structure to meet its intended service life, as envisaged at the time of design; and
* Conservation activities with the intention to prolong the planned service life of a structure or to enable it to meet altered performance requirements (e.g., altered loading or functionality needs). In the paper, only the objective of enabling the structure to meet its intended service life was observed. This is because it is assumed that when a measurement is performed, only the information on the current chloride content is available, and an extrapolation of the process and forecasting future content was not taken into account. In the Model Code 2010 [9], the choice of conservation strategy is seen as being dependent on numerous factors, the most important of which are:  
* Consequences of a potential failure;
* Feasibility of evaluating the condition of the structure;
* Predictability of the service life of the structure or its components;
* Recording and quantification of the actions that occur during the service life of the structure;
* Feasibility of preventative or remedial interventions (e.g., repairs, replacements etc. ); and
* Cost of conservation activities. From these factors, only the factors related to the conservation of the serviceability limit state were observed in the analysis, i.e., the possible consequences of actual structural failure were not considered. According to [58], the conservation strategies were characterized based on their proactive versus reactive characteristics as follows:  
* Proactive conservation activities;
* Reactive conservation activities; and
* Situations where conservation activities are not feasible. A proactive conservation strategy is based on preventive (or protective) interventions and measures. These measures are primarily intended to avoid and minimize future deterioration by implementing some form of treatment or taking action prior to damage becoming detectable. This approach should enable early identification of problems and possible risk issues affecting the condition of the structure, and is hence deemed as desirable. Furthermore, the approach should potentially enable early preventive action to be taken to minimize the overall cost of ownership [58]. It is important to mention that this paper focuses only on the repair activities as possible methods of structural conservation, and does not consider other options, such as replacement, demolition, etc. Eleven possible principles for concrete repair and protection were summarized, when the European Standards 1504 were fully introduced in 2009 [59]. The recommendations given in the European Standards 1504 should assist engineers in the selection of a method that would repair or retard (potential) damage in reinforced concrete structures. When observing these principles, a systematic division into two groups can be noticed, i.e., principles related to defects in concrete and principles related to reinforcement corrosion. Principles related to defects in concrete were divided into protection against ingress, moisture control, concrete restoration, structural strengthening, increasing physical resistance, and increasing resistance to chemicals. On the other hand, principles related to reinforcement corrosion were divided into preserving or restoring passivity, increasing resistivity, cathodic control, cathodic protection, and control of anodic areas. [PERSON] and [PERSON] [60] assigned examples of methods of repair to each of these principles. Some of these repair principles and specific methods can be applied as both proactive and reactive measures while others just as one of these strategies.