About the efficiency of migrating inhibitor protection from reinforcing corrosion of reinforced structures
The test results of the KCR and DME migrating inhibitor efficiency have been presented. The method of linear polarization was used in the tests on loaded test elements of reinforced concrete. Different time of inhibitor action, crack of concrete cover and different levels of reinforcement corrosion development in test samples were taken into account. The inhibitors were efficient only in samples with low level of corrosion development in first period, however after two years the protective action was not identified. In the case of extensive reinforcement corrosion the reduction of its level was not observed even directly after inhibitor application.
Key words: concrete, inhibitor, corrosion, efficiency, protection, reinforcement, reinforced concrete
Evaluation of predicted durability of randomly corroded side surface sheets in cylindrical steel tanks with vertical axis
The methodology behind the assessment of the durability of corroded side surface steel sheets in operating cylindrical tanks for liquid fuels with vertical axis has been proposed in the paper. The random nature of the corrosion process in particular sheets has been taken into account. The measurement data obtained during the inspection of the sheets’ real thickness which has deteriorated as a result of corrosion, allow the assessor to perform a reliable evaluation of the probability of failure in the future. Particularly, the predicted time (mean and design values) for the fail-safe operation of the tank, remaining until the deterioration of the tank’s load-bearing capacity, can be determined, providing that the level of failure probability, accepted by the tank user, has been assumed.
Key words: corrosion, steel tanks, safety, failure probability, durability
Harmfulness of moulds occurring in human environment
The enzymatic activity of 3 moulds species: Cladosporium cladosporioides, Alternaria tenuissima and Stachybotrys chartarum was evaluated with the use of the API ZYM system. The investigated strains were incubated in the liquid Sabouraud medium containing building substrates or their components. Centrifuged culture supernatants were used to assess the activity of enzymes, presented as amounts of hydrolised substrate in nanomols, depicted on a scale from 0 to 5. This investigation revealed a high enzymatic activity of Cladosporium cladosporioides. In contrast, Alternaria tenuissima and Stachybotrys chartaru were characterised by a low activity of hydrolytic enzymes. The amount of produced enzymes varied depending on the medium used. All the investigated moulds were characterised by both a high activity of alkaline and acid phosphatase, esterase (C4), esterase lipase (C8) and naphtol-AS-BI-phosphohydrolase. A signifi cant infl uence of the building materials environment on the production of hydrolytic enzymes by moulds was observed. Particular building materials or their components stimulated the production of respective enzymes. The resemblances in the enzymatic activity between the control strains and the strains grown on the medium with building materials bring to the conclusion that the strains could be a potential source of human infection. Moreover the results demonstrate that none of the existing mould species produces hydrolases in environments containing fungicidal substances.
Key words: moulds, enzymatic activity
Comparative analysis of the alternating current polarization ranges tests on the reinforcing steel under the passivation and the corrosion conditions
Test results of alternating current polarization ranges on the reinforcement models in solutions simulating the concrete pore liquid – performed by EIS method – were presented in the paper. Three electrochemical states of the reinforcement surrounded with the concrete cover that occur frequently in reinforced concret: passivation, uniform corrosion caused by loss of protective properties by the whole concrete cover and the local corrosion occurring in the cracked zones of concrete were tested. Three counter electrodes were used to asses influence of polarization ranges on the reinforcement models. Dependencies between the length of counter electrode and the charge transfer resistance were found. A real value of corrosion rate of steel was determined in the measuring vessel. The paper is a continuation of the direct current polarization range tests  on the reinforcement, but in the alternating current version.
Key words: diagnostic of reinforced concrete structures, reinforcement corrosion, electrochemical impedance spectroscopy, polarization range