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.
Abstract: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.
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