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Characterization of Manmade and Recycled Cellulosic Fibers for Their Application in Building Materials

Journal of Renewable Materials 2019年第11期7卷 1121-1145页

作者： nadezda stevulova Viola Hospodarova Adriana Estokova Eva Singovszka Marian Holub Stefan Demcak Jaroslav Briancin Anton Geffert Frantisek Kacik Vojtech Vaclavik Tomas Dvorsky Technical University of Kosice Faculty of Civil EngineeringInstitute of Environmental EngineeringVysokoskolska 404200 KosiceSlovakia Institute of Geotechnics of the Slovak Academy of Sciences Watsonova 4504353 KosiceSlovakia Technical University in Zvolen Faculty of Wood Sciences and TechnologyDepartment of Chemistry and Chemical TechnologiesT.G.Masaryka 2117/2496053 ZvolenSlovakia VSB-Technical University of Ostrava Faculty of Mining and GeologyDepartment of Environmental Engineering17.listopadu 15/217270833 Ostrava-PorubaCzech Republic

The aim of this study was to characterize two types of cellulosic fibers obtained from bleached wood pulp and unbleached recycled waste paper with different cellulose content(from 47.4 percent up to 82 percent),to compare and to analyze the potential use of the recycled fibers for building application,such as plastering *** in the chemical composition,cellulose crystallinity and degree of polymerization of the fibers were *** recycled fibers of lower quality showed heterogeneity in the fiber sizes(width and length),and they had greater surface roughness in comparison to high purity wood pulp *** high purity fibers(cellulose content>80.0 percent)had greater crystallinity and more homogeneous and smooth surfaces than the recycled *** presence of calcite and kaolinite in all of the recycled cellulosic fibers samples was confirmed,whereas only one wood pulp sample contained *** influence of the chemical composition was reflected in the fiber density *** in the chemical composition and cellulose structure of the fibers affected the specific surface area,porosity and thermo physical properties of the *** favorable values of thermal conductivity were reached for the recycled fibers than for the wood pulp *** the suitability of the recycled fibers with inorganic impurities originating from the paper-making processes for their use as fillers in plastering mortars(0.5 wt.%fiber content of the total weight of the filler and binder)confirmed their application by achieving a compressive strength value of 28 day-cured fiber-cement mortar required by the standard as well as by measured more favorable value of capillary water absorption coefficient.

关键词： Wood pulp waste paper fiber properties characterization compressive strength of mortars

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Effective Utilization of Coal Fly Ash in Building Material Production

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Journal of Chemistry and Chemical Engineering 2011年第8期5卷 724-728页

作者： Jozef Junak nadezda stevulova Civil Engineering Faculty Institute of Building and Environmental Engineering Technical University of Ko~ice Vysoko3kolsk6 404200 Kokice Slovakia

This paper is aimed at verifying utilization possibilities of alkaline modified coal fly ash as cement replacement in the concrete. The influence of alkaline activated coal fly ash originating from Slovakian power plant in Novsky （Si/Al = 3,1） as a partial cement replacement in concrete on compressive strength of hardened composites after 28 and 90 days was investigated. Alkaline activation of coal fly ash was realized in an autoclave at 130 ℃ and pressure of 160 kPa during 5 hours and in a reactor under normal conditions （equal temperature during 36 hours） at solid/liquid ratio of 0.5. Coal fly ash/cement mixtures were prepared with 25 % cement replacement by starting and modified coal fly ash and given in forms. Compressive strengths of composites after 28 and 90 days of hardening were compared to referential composite without coal fly ash and evaluated according to the standard of STN EN 450 by the value of relative strength KR （compressive strength of coal fly ash/cement composite to compressive strength of comparative concrete）. The final compressive strengths of hardened composites based on alkaline activated coal fly ash reached values in the range of 6 up to 50 MPa. In the set of experimental composites based on alkaline activated coal fly ashes, the highest value of relative strength after 28- and 90- days of hardening reached composite with cement replacement by coal fly ash zeolitized in autoclave （105% of compressive strength of referential sample）, what is connected with formation of zeolitic phases on surface of coal fly ash particles. The achieved results confirm that alkaline activation of coal fly ash in an autoclave under observed conditions can be successfully used as a partial cement replacement in concrete of C20/25 and C25/30 in accordance with requirements of standards （STN EN 450 and STN EN 206）.

关键词： coal fly ash chemical activation concrete compressive strength zeolite

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Characterization of Cellulosic Fibers by FTIR Spectroscopy for Their Further Implementation to Building Materials

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American Journal of Analytical Chemistry 2018年第6期9卷 303-310页

作者： Viola Hospodarova Eva Singovszka nadezda stevulova Institute of Environmental Engineering Technical University of Ko&#154 ice Ko&#154 ice Slovakia

Nowadays, the material recycling is a growing trend in development of building materials and therefore using of secondary raw materials for production new building materials is in accordance with sustainable development in civil engineering. Therefore, it is increasingly becoming crucial to accelerate the transition from application of non-renewable sources of raw materials to renewable raw materials. One fast renewable resource is natural plant fibers. The use of the cellulosic fibers as environmentally friendly material in building products contributes to the environmental protection and saves non-renewable resources of raw materials. Wood fibers and recycled cellulose fibers of waste paper appear as suited reinforcing elements for cement-based materials. In this paper, there is used application of Fourier transform infrared spectroscopy (FTIR) on cellulose fibers coming from different sources. FTIR spectra of cellulose fiber samples are investigated and compared with reference sample of cellulose.

关键词： Renewable Raw Materials Cellulose Fibers Infrared Spectroscopy

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Low-temperature Synthesis of Belite Cement from Reactive Mixtures Based on Coal Fly Ash

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Journal of Civil Engineering and Architecture 2012年第2期6卷 189-196页

作者： nadezda stevulova Ivana Filkova Kestutis Baltakys Institute of Building and Environmental Engineering Civil Engineering Faculty Technical University of Kosice 042 O0 KosiceSlovak Republic Department of Silicate Technology Faculty of Chemical Technology Kaunas University of Technology Radvilenu st. 19 C-144 L T- 50254 Kaunas Lithuania

This paper summarizes the selected results of an extensive investigation of application of two methods （hydrothermal and mechanochemical） assisted by calcination for synthesizing belite cement from reactive mixtures （CaO/SiO2 molar ratio of 2） consisting of various waste kinds from fluidized brown coal combustion in Slovakian power plant and CaO addition. Based on XRD diffraction patterns and infrared spectra ofpre-treatment products, the formation of the new profiles corresponding to CSH phases with low degree of ordering as belite precursors after hydrothermal treatment as well as metastables calcium silicates and aluminosilicates in mechanosynthesized products was confirmed. Calcination of hydrothermally treated products led to transformation of CSH phases to wollastonite （CS）, belite and gehlenite phase, whereas creation oft^- and I^-C2S or wollastonite in milled reactive mixture took place. Differences in phase composition of products before and after calcination depend upon waste quality and precursor＇s synthesis conditions. Bottom ash isn＇t suitable as raw material for synthesizing belite phase because of high CaO content fixed in anhydrite form （44.1%）. Coal fly ash with low CaO content in anhydrite form （4.2%） and its mechanochemical or hydrothermal treatment in combination with subsequent heating offer opportunities for the utilization of coal fly ash as raw material for belite production.

关键词： Coal fly ash hydrothermal pre-treatment mechanosynthesis belite.

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The Study of Resistance of Cement Composites against Microbial Attack

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Journal of Civil Engineering and Architecture 2011年第6期5卷 555-561页

作者： Estokova Adriana Ondrejka Harbulakova Vlasta Luptakova Alena Prascakova Maria stevulova nadezda Institute of Building and Environmental Engineering Faculty of Civil Engineering Technical University of Kosice Slovakia Institute of Geotechnics Slovak Academy of Science Slovakia

The start and the course of bio-corrosion are conditioned by many factors which include biological effects like the influence of vegetation and microorganisms causing the deterioration of materials. The influence of bacteria causing the deterioration of concrete has been linked to the generation of biogenic sulphuric and nitric acids which originate in corrosion process by dissolution of calcium containing minerals from the concrete matrices. This paper primarily focuses on the investigation of influence of sulphur-oxidising bacteria Acidithiobacillus thiooxidans and sulphate-reducing bacteria Desulfovibrio desulfuricans at the resistance degree of cement composites. Various concrete composites with 5% addition of black coal fly ash as cement replacement as well as the reference samples without coal fly ash addition were studied in the experiments environments of sewage system proceeded during 90 days. The The laboratory experiments as well as experiments in situ in real corrosion was manifested by surface changes and weight changes of cement composites samples as well as changes in pH values of leachates. Considerable surface changes were detected in all investigated samples by microscopic methods. Crystals precipitated on concrete samples surface were identified by EDX as mixture of gypsum and ettringite. The roughness increases of surface of cement microscopy. composites were determined by confocal laser scanning

关键词： Concrete MIC bacteria biocorrosion biodeterioration.

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