The paper presents the effect of the addition of polymers for mortars with CEMI to their durability under conditions of activated sludge wastewater treatment plant. The change of tightness studied materials was estimated as a result of action of medium involving 108÷109 microorganisms in 1 the ml of settlings The results of research showed significant changes of tightness materials, in particular mortars modified with acrylics and polysiloxanes. The activated sludge resulted in two opposing processes: the unsealing of the structure and deposition of corrosion products.

Hot dip zinc coatings are commonly used in the urban and road infrastructure as individual corrosion protective coatings or as duplex system. The decreasing durability of protective systems below expectations and problems with adhesion between a zinc coating and an organic coating in duplex system occur in both applications. Examples of these failures and, for selected cases, causes of their occurrences are showed. Not always the failure cause is easy to find. Therefore the fundamental research are undertaken to find relationship between a composition and a structure of zinc coating and anticorrosive properties in both protective systems. The first test results are presented.

The effect of the electrochemical injection of nitrite ions on the corrosion of steel in carbonated mortar was studied at anodic current density of 0.2 A/m2. Almost 100- fold acceleration of the inhibitor transport was found. Estimated effectiveness of the inhibition of steel corrosion of steel was about 94%. The reduction pH and nitrite oxidation in the anodic chamber were observed. In addition, a non-uniform corrosion damage of embedded steel, probably caused by stray current, was found.

In the paper, the possibility of using dialkyloaminomethylophosphonic or bis(dialkylamino- methyl)phosphonic acids as a new non-toxic inhibitors of the corrosion of steel for concrete reinforcement was investigated by potentiodynamic method.

The paper presents a numerical model describing the destruction of RC elements due to simultaneous action of chemical corrosion and the load. Particular attention is paid to the modeling of diffusive cross-effects by cellular automata of Neumann's and Moore's type. The scalar parameter describes the cross-section deterioration taking into account different damage mechanisms: brittle, plastic and chemical. The decrease with time of the cross-section strength is assessed by means of series of the numerical experiments.

The rate of corrosion of the reinforcement in structures subjected to the influence of atmospheric factors is variable in time. Previous attempts to model this parameter as a function of temperature and humidity and the content of chloride ions in concrete have taken into account all these factors simultaneously [1–3]. Such an approach may cause some irregularities in the interpretation of test results. This paper attempts to analyze the variability of rebar corrosion rate along with the parameters which determine its value at constant humidity and temperature of the concrete surrounding the reinforcement in the initial stage of corrosion.

The subject of this paper is an overview of the world standards requirements for concentration of chlorides in reinforced and prestressed elements, taking into account other factors. Factors affected on the level of the critical concentration of chloride sufficient to initiate corrosion of steel were considered. The results of tests for a critical chloride concentration initiating steel corrosion and standard limits were compared.