## 4 Discussion Based on Practical Examples
### Discussion on the Possibility of Repair  
The classification of damage (described above) and the decision to undertake repairs is not always strict, because it depends on a number of factors with difficult to determine weights. An external visual inspection of the structure allowing assessment of the level of damage is not a clear premise for making a decision about the ability of the structure to carry out effective and durable repairs. Despite this, in many cases, only on this basis decisions are made about the further fate (in terms of repair or dismantling) of the object.  
Figure 5: Damage of varying intensity: (**a**) damage of concrete and steel corrosion of rebars and profiles, (**b**) strong corrosion of steel elements used as the strengthening of concrete beams.  
Figure 6: The very bad condition of structural elements: (**a**) swelling steel rebars caused damage of the concrete cover, (**b**) damaged steel strengthening and concrete of columns.  
In the authors' opinion, the results of chemical tests served as an argument in the discussion about the final and responsible qualification of the structure for repairs or the decision to demolish it. It can be assumed, based on the authors' many years of experience, that the combination of very strong concrete contamination with harmful ions and a low pH was a clear premise for the demolition of the structure--especially if the expected lifetime exceeded 10 years.  
In the general case, it is also necessary to take into account the possibility of liquidation of a given structure due to the continuity of technological processes in the industrial plant--in some specific cases such processes are continuous and it is impossible to stop them (e.g., operation of a blast furnace in a steel plant). In such cases, renovation may be necessary even if the condition of the structure actually precludes the sense of such activities.  
In the presented case studies, the decision on further use of the facilities took into account all factors, including the results of chemical tests. In each case, the lifetime of the structures was foreseen for the next 25-30 years. All the structures from group B, despite having a weak concrete (C12/15) showed a low level of chemical contamination and relatively high pH value indicating a small loss of the protective capacity of concrete. This allowed the structure to be qualified for repair, and also guaranteed its effective and durable performance. The elements were repaired--since that time, they have been operated for nearly 15 years without signs of corrosion. Concerning the structures A and D, which indicated the worst technical condition, the decision ordered the dismantling of the parts above the floor or ground level (structure D). The chemical contamination of those structures was very high, which did not provide effective repairs, especially that the area where they had to be made was very extensive (structure D). The repair of the underground parts has been approved on condition that their appropriate condition was proved, including via chemical tests--the latter was not available at the time of conducting the evaluation. The entire part above the floor level of the structures C1 and C2 were also qualified for dismantling. Despite the fact that this structure was made of relatively good concrete, with a satisfactory pH value (partially carbonized concrete), the intensity of damage observed as well as very high chemical contamination of concrete disqualified it from continued use. The technical condition of the underground foundation slabs was good, so it was decided to order the repair and reuse of them.