On the base of literature data the characteristic features of impedance spectra of steel in cement paste, mortar and concrete were described. Spectra analysed on the Nyquist plot consist of high-frequency features of concrete and low-frequency features of steel. As part of the electrode-related feature it is possible to distinguish two fragments of spectrum marked with letters 'A' and 'B'. The feature 'A' is being associated with properties of the oxide fi lm on the steel, however for feature 'B' the properties of double-layer of steel-concrete pore-liquid are being assigned. As part of the bulkrelated feature it is possible to distinguish three fragments of spectrum marked with letters 'C', 'D' and 'E'. The features 'C' and 'D' are most often identified with electric properties of double layer in the interface of liquid and solid phase of concrete, while feature 'E' with the resistance of the pore-liquid. As an alternative diversifi ed electric properties of three different conductive paths in concrete are being assigned to the entire bulk-related feature of the spectrum. In the paper differences in shapes of spectra of passive and corroding steel were shown, which are emerging in the electroderelated part. Moreover an influence of the cement hydration process on shapes of

Reinforcing steel in concrete is not subjected to corrosion until a change in physicochemical properties occurs of concrete under the influence of aggressive agents – carbon dioxide and chloride ions, which with time penetrate inside the reinforced concrete structure. Concrete, especially moist concrete, is a good electric current conductor and hence steel can be protected against corrosion with the use of cathodic protection. The paper describes the basis of reinforced concrete cathodic protection, applied sub-assemblies and protection installation elements, as well as typical technical applications of this technology. European standard requirements also have been described, connected with this anticorrosion protection method.

Moulds are common in dwelling buildings and grow on various building materials. This phenomenon is observed not only in the old buildings, but also in the new constructions where modern technologies where used. Today modern interior design is based on acrylic paints. During the research conducted in Lubuskie Province of Poland 18 species of moulds have been isolated and identified from exterior and interior walls and barriers covered by acrylic paints and plasters.

The presence of chlorides and water increases the corrosion activity of ionic liquid even at room temperature. The corrosion rate of the examined materials increases with the increase of concentration of impurities. Below the temperature of thermal decomposition of ionic liquid the corrosion rate increases with temperature. In ionic liquid containing water and chlorides (0.87% Cl and 1.3% water) due to synergetic effect results in an increase of current density of copper corrosion by as much as two orders of magnitude, and of zinc and steel by one order. At the same time pitting corrosion is increased. The presence of chlorides in the ionic liquid accelerates the process of thermal decomposition of the liquid. In the presence of copper the process of thermal decomposition of chloride-containing ionic liquids is faster than in the case of steel and zinc. The layers of corrosion products composed of the metal corrosion products and products of the ionic liquid thermal decomposition are well adhesive, stable, and exhibit good protective properties, as a result of which the corrosion rate is considerably reduced. In the presence of chlorides and water, and particularly when both those impurities are present in the corrosive medium, the content of boron, fluorine and chlorine in the corrosion products increases. The layers of corrosion products formed at temperatures of 150 and 200oC contain greater amounts of carbon, fluorine, boron and chlorine originating from decomposition of the ionic liquid.