Utilization of pozzolanic materials (fly ash, slag, zeolite, metakaolin, microsilica and more) in the manufacturing of cement and concrete has increased considerably over the last decades. Another option is to use concrete containing sulfate resisting cement. This could help minimize the harmful impacts on concrete exposed to an aggressive environment. The issue of the deteriorative impact of the three types of concrete corrosion (acidic, sulfate and leaching) investigated using correlation analysis is presented in the paper. Concentrations of silicon and calcium leached out from the concrete samples into the liquid phase and the measured pH values were used as input data for a mathematical approach to the study of sulfate resisting cement. The performance of sulfate resisting cement-based concrete was improved when exposed to sulfate attack, but not in the case of leaching corrosion caused by water.

The issue of the building materials biodeterioration has a significant economic dimension because it results in the costly repair. The start and the course of corrosion are conditioned by many factors which undoubtedly include biological effects like the influence of vegetation and microorganisms causing the so called microbial corrosion. Microorganisms have also a considerable share in the decay and degradation of different building materials.

External sulfate attack is detected on concrete construction exposed to soils, groundwater, seawater, or wastewater, and leads to serious damage to concrete elements. This paper describes an investigation of acidic corrosion caused by artificial sulphuric acid and biogenic sulphuric acid. The concrete prisms prepared from concrete-containing sulfate-resisting cement were exposed to an acid environment of different origin over a period of 3 months. The concentration of basic chemical elements such as calcium, silicon, iron, and aluminium were measured in liquid phases. Correlation analysis was used to evaluate dependencies and trends of leached-out amounts in these concentrations. Based on correlation coefficient, the intensity of dependency of the leaching trend was determined. A higher aggressiveness of sulfuric acid produced by sulfur-oxidizing bacteria was confirmed in terms of main concrete components’ leaching.

The Framework Directive 2009/28/EC on the promotion of the use of energy from renewable sources aims at developing the local and regional electricity market in order to reduce greenhouse gas emissions. A comparison study of the proposed activities of construction of a new biomass-fired power plant or reconstruction of an old one-gas power plant in town located in eastern Slovakia is presented in this paper. The method of the index coefficient was used for choosing the best alternatives. Multicriteria analysis proved that the construction of biomass-fired power plant is the most suitable solution chosen from three assessed variants (no activity is implemented, biomass power plant and modernized gas boiler).

The loss of mass of concrete matrix and subsequent corrosion of concrete has been reported very often. Aggressive liquids such acids, bases, solutions of salts or aggressive gases as well as microorganisms penetrate the concrete and cause deterioration and biodeterioration, respectively. Presented paper is aimed at investigation of concrete corrosion (chemical as well as biologically induced) activated by influence of different aggressive media. Concrete cylinder samples of a 32 mm diameter and 15 mm height were formed as a drilled core from prepared concrete cubes. Concrete samples were exposed to different aggressive media under laboratory conditions (acid mine drainage, cultivation media for different bacteria species, sulphuric acid, aluminium sulphate) as well as in situ (waste water of sewage system in Kosice city) for 3 months. Influence of aggressive media and sulphur-oxidising and sulphate-reducing bacteria on concrete samples has been determined in terms of weight and surface changes of investigated concrete samples and leaching of the selected ions. The weight changes varied in the range 0.04–3.7 %. The visual changes of samples surface were observed. Content of Ca, Si and Fe ions in leachates were measured by X-ray fluorescence methods. Higher percentage of calcium ions released has been measured comparing to silicon ions in all media except for distilled water. The results of elements releasing correspond to results of weight changes of investigated concrete samples.

The activity of microorganisms plays a very important function in the whole spectrum of degradation processes such as corrosion of metals and concrete, the plugging of the pipeline and filters in consequence of the biofilms creation or the efficiency reduction of heat exchangers. The microorganisms that cause microbiologically influenced corrosion of concrete are ubiquitous in the environment and they produce either organic or inorganic acids that can dissolve and disintegrate the concrete matrix. This paper is focused on the concrete biocorrosion’s study in real sulfuretum conditions — in a sewer pipe with wastewater in Košice city. Concrete samples with addition of 5 and 10% of coal fly ash respectively as well as reference samples without coal fly ash addition were used for the experiment. The weight changes and surface changes of concrete samples were valuated after 4-month exposition to the real sulfuretum influence. The concrete biodeterioration studies in sewer pipes suggest the analogical biodegradation processes for all samples, whereby the composition of concrete and duration of aggressive environment influence are also important