Search Results

You are looking at 1 - 10 of 10 items for

  • Author or Editor: Adriana Eštoková x
  • All content x
Clear All Modify Search

Deterioration of concrete materials exposed to an aggressive solution is often characterized by the leaching of calcium and silicon compounds from the cement matrix. This paper presents the results of the study of concrete composites exposed to the various sulphate environments (sulphuric acid and magnesium sulphate solutions) under laboratory model conditions. The leaching of the calcium and silicon from concrete specimens has been studied during 180 days using X-ray fluorescence method for leachate analysis. As expected, sulphuric acid of pH3 was confirmed to have the most significant effect on the studied ions releasing. The released amounts of analysed ions were 192.2 and 9.6 times higher for calcium and silicon ions, respectively in H2SO4 with pH=3 when compared to fresh water. The concentration of released calcium was 2.6 times higher

Restricted access

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.

Restricted access

Building industry is responsible for 1/3 of total CO2 emissions and consumes 40% of primal energy in the industry. This paper presents the results of environmental impact assessment of building materials in three houses based on Life Cycle Assessment of the whole life cycle. Building materials were evaluated by special tool by Createrra. CO2 emissions related to life cycle of building materials vary from 0,176 kg CO2eq/kg − 0,305 kg CO2eq/kg, SO2 emissions range form 0,836 g SO2eq/kg − 1,656 g SO2eq/kg and primal energy intensity reached values from 2,347 MJ/kg to 2,534 MJ/kg.

Restricted access

Green buildings are more comfortable than conventional buildings; thereby making them more satisfying and productive workplaces, there is little empirical evidence to support this belief. The aim of the case study was to test the hypotheses that indoor parameters in green buildings in dependence on building materials and structures are more suitable than in buildings with conventional materials and structures. These hypotheses will be test for comparing the green buildings and conventional buildings in term of the comfort and satisfaction of the occupants.

Restricted access
Pollack Periodica
Authors: Jozef Oravec, Aneta Petriláková, Vladimír Zeleňák, Magdaléna Bálintová, and Adriana Eštoková

Mesoporous silica SBA-15 without and with modification of surface by grafting with aminoalcoxysilanes is prepared is the experiment. The prepared samples are characterized by adsorption/desorption of nitrogen. Results confirms the prepared materials having a specific surface area up to 846m2/g, which are improved for the capture of metals by grafting with the amino group. The sorption of Cu2+ cations as well as SO4 2− anions from the acidic solution is investigated. The modified mesoporous silica is confirmed to have better sorption capacity than unmodified mesoporous silica.

Restricted access
Pollack Periodica
Authors: Marcela Ondova, Nadezda Stevulova, Lenka Palascakova, and Adriana Estokova

The current annual worldwide production of by-products is estimated about 700 million tons of which 70 % is fly ash at least. Large quantities of fly ash are available at low costs around the world and its use in concrete seems to offer the best solution to reduce its consumption. With regard to these facts and Slovak needs, the chemical and mechanical properties of hardened concrete composites with various share of fly ash were studied. Other focus of this study is the investigation of the influence of different chemical admixtures on development of the concrete properties, their environmental and economic impacts.

Restricted access
Pollack Periodica
Authors: Vlasta Harbuľáková, Adriana Eštoková, Alena Luptáková, Nadežda Števulová, and Gabriel Janák

Biodeterioration can be seen as a process, which decreases value of materials and constructions and has been defined as the deterioration of materials of economic importance by organisms. Since the discovery bacterial genus Acidithiobacillus caused rapid corrosion of concrete especially Acidithiobacillus thiooxidans .This paper presents the results of concrete specimens’ biodeterioration study by bacteria Acidithiobacillus thiooxidans and Desulfovibrio genera under model conditions. Biodeterioration was carried out in laboratory reactor, where simultaneous effect of Acidithiobacillus thiooxidans and Desulfovibrio genera happened. The pH values of leachate, mass of concrete specimens change, Ca and Fe content in leachate were evaluated. After experiment the morphology of corroded surface were observed by scanning electron microscopy.

Restricted access
Pollack Periodica
Authors: Lenka Palaščáková, Adriana Eštoková, Magdaléna Bálintová, and Aneta Petriláková

Cements are one of the building product groups in Slovak republic for which the required criteria are stated and the national eco-label is possible to obtain. One of the criteria for an award eco-label for cements is the limitation of the occurrence of chromium (VI) in cements. The selected types of cements were assessed and average values of soluble chromium (VI) for each type of cements were compared to the requirement in Slovak eco-labeling process — 1.8 mg chromium (VI) per 1 kg of cement (1.8 ppm). The measured values of soluble chromium (VI) content in common used types of cements were higher than eco-labeling limit at almost of 60% of evaluated cements.

Restricted access

Leaching of calcium ions increases the porosity of cement-based materials, consequently resulting in a negative effect on durability since it provides an entry for aggressive harmful ions, causing corrosion of concrete. Sulphuric acid corrosion of concrete can be caused due to attack of aggressive media naturally existing in the environment. Another possibility of corrosion formation is biogenic acid effect through the agency of microorganisms.

The paper is focused on the investigation of the influence of biogenic acid attack on the cement composites affected with bacteria Acidithiobacillus thiooxidans. The concrete specimens with 95% wt. addition of antimicrobial activated granulated blast furnace slag as durability increasing factor as well as without any addition were studied. The experiments proceeded during the nine 7-day cycles. The pH values and chemical composition of leachates were measured and evaluated after each cycle. The higher resistance of concrete samples with the addition of 95% wt. of antimicrobial activated granulated blast furnace slag to the aggressive environment was confirmed. The leaching of calcium ions of concrete sample affected with bacteria Acidithiobacillus thiooxidans was 1.13 times lower (736.6 mg/L of leachate) for concrete sample with antimicrobial activated granulated blast furnace slag addition comparing to concrete sample of ordinary CEM I Portland cement without any additives (832.0 mg/L of leachate).

Restricted access

The paper presents the results of leachability testing of selected heavy metals from the concrete composites of various compositions in order to assess the degree of a contamination risk of the environment. Tested concrete samples contained various amounts of special ingredients based on the blast furnace slag (65%, 75%, 85% and 95% of Portland cement replacement). Leaching tests have been performed by using distilled water. The concentrations of chromium and barium ions in the leachates were measured after period of 30 and 240 days. Changes in pH and conductivity values in leachates have been also observed.

Restricted access