Macro and nano dimensional plant fiber reinforcements for Cementitious Composites

uncorrected proofNowadays, the use of plant fibers in the civil construction industry is growing rapidly due to their low cost, light weight and good specific mechanical properties, lower health hazard, and environmental benefits. Nanodimensional fibers derived from plants such as nanocellulose are also getting considerable attention due to their excellent mechanical properties. This chapter discusses these different types of plant fibers and their derivatives which have huge application potential in the civil construction sector. The influence of plant fibers on microstructure as well as on physical–mechanical properties of cementitious composites are discussed in detail. The challenges regarding plant fiber processing and dispersion, the fiber/matrix interface, and the durability of plant fiber-cement composites are also addressed. The application of nanocellulose in polymer composites has been included in this chapter just to provide the readers sufficient background information and techniques to inspire engineered cement-based composites. Finally, the chapter concludes with the current application of plant fibers in civil construction and the future trends(undefined)info:eu-repo/semantics/publishedVersio

Application possibilities of photovoltaic power for telecommunication systems

Šiame darbe atlikti konteinerinio tipo automatinės telekomunikacijų stoties (ATS), elektros energijos poreikių tyrimai. Tyrimų metu nustatyta, kad ATS kuri teikia fiksuoto ryšio paslaugas 250 vartotojų ir interneto prieigos paslaugas 156 vartotojams, per metus sunaudoja apie 6582 kWh elektros energijos, iš kurios apie 24 % (1550 kWh) sunaudojama įrangos kondicionavimui. Tyrimais nustatyta, kad elektros energijos suvartojimas tiesiškai priklauso nuo aplinkos oro temperatūros. Ištyrus ATS elektros energijos vartojimo ir saulės energijos kaitos dinamiką statistiniais metodais, nustatyta, kad apie 5326 kWh saulės energijos, konvertuotos į elektros energiją, galima naudoti tiesiogiai. Tai sudarytų apie 81 % nuo visos ATS suvartojamos energijos per metus.In this study are analyzed a container – type automatic stations of telecommunications (ATS) electrical energy demand. There is investigated that ATS, which provides services of fixed connection for 250 users and internet access services for 156 users, consumes per year about 6582 kWh of electrical energy. About 24 % (1550 kWh) of this amount was consumed for conditioning of the equipment. It was found the linear correlation between energy demand and ambient temperature of the station. Investigation of the ATS electrical energy consumption and dynamics of solar energy changes using statistical methods found that about 5326 kWh of solar energy converted into electrical power can be used directly. This would represent about 81 % of the total energy consumption of ATS during the year.Žemės ūkio akademijaVytauto Didžiojo universiteta

Lightweight Concrete with an Agricultural Waste – Buckwheat Husk

This paper presents a parametric experimental study which investigates the potential use of buckwheat husk wastes (as an aggregate in concrete) and opoka combination for producing a lightweight composite. The study was carried out to investigate the influence of the buckwheat husk extract on the setting and hardening of pastes in which cement was partially replaced by 0, 33, or 50 % of natural pozzolana. The kinetics of hydration up to 48 h was studied using isothermal conduction calorimetry. Some of the physical and mechanical properties of buckwheat husk concrete with various levels of cement replacement of opoka without and with sand (part of buckwheat husk was replaced in the same volume of sand) were investigated. Experimental data on the compressive strength of concrete utilizing buckwheat husk with and without sand and cement at varying proportions are presented. The results suggest that buckwheat husk may be used as an aggregate, particularly in lightweight concrete, panel and blocks for walls at a relatively cheaper price. </p

Modified sawdust concrete/Modifikuotas pjuvenų betonas

Wood-cement materials are widely produced and applied in many developed countries. In this case special prepared wood aggregates are employed. Wood sawdust practically is not employed. Extracts, present in wood, slow down the cement hydration. The influence of mineral additives on this process was determined. The efficiency of mineral additives depends on their hydraulic activity. It has been found that the mineral components (additives) of sawdust concrete have a positive effect on cement setting and hardening due to two reasons: 1) hydraulic and other mineral additives absorb wood extracts from liquid phase which inhibit and retard setting of cement and reduce their concentration in solution; 2) reduce pH of liquid phase so the hemicellulose which is in sawdust or other wood aggregates, less disintegrate lightly soluable sugars. When sawdust amounts are different, the optimum cement and rottenstone relation is not constant: y = 1,29x −0,66 where y is cement and rottenstone mass relation, x is sawdust and binding material (cement+rottenstone) volume relation. The influence of sawdust concrete humidity on its strength was found: where y is concrete compressive strength (MPa), when its humidity X (%), R is concrete compressive strength (MPa), when its humidity W(%). The possibility of accelerating the hardening process of concrete mixes of cement-rottenstone (gaize)-sawdust system by means of steaming at 80 °C was studied, too. It is impossible when producing ordinary wood-cement materials. The physical and technical properties of sawdust concrete such as shrinkage strain, expansion deformations and elastic modulus were determined. Sawdust concrete contraction deformation depending on concrete density may vary by 8…14 mm/m and expansion (in humid conditions) by 1,1…2,5 mm/m. Deformation decreases when quartz sand additive is used. When the concrete gets dry repeatedly, deformations are smaller. The sawdust concrete elasticity modulus is similar to that of light concrete with inorganic additives having the same density. Its frost resistance depends on the concrete structure and cement quantity. When the concrete with a small amount of sawdust is used (cement+additive: sawdust=5:1), the samples endure 75 freezing cycles. The heat conductivity of sawdust concrete is low. The experimental data have shown that structural thermoinsulated small blocks can be produced from these concrete mixes. First Published Online: 26 Jul 201

Keramzito gamyba naudojant nesipučiantį molį, sapropelį ir glicerolį

&Scaron;io darbo tikslas - i&scaron;tirti keraminių plytų ir čerpių gamybai netinkančio, silpnai pučiančiosi (i&scaron;sipūtimo koeficientas <em>K_p</em>&nbsp;=&nbsp;2_&nbsp;-_&nbsp;2,5) ir nesipučiančio (<em>K_p</em>&nbsp;&lt;&nbsp;2) molio panaudojimo keramzito gamybai galimybes, molio pūtimuisi gerinti dedant &scaron;ių organinių priedų: biodyzelino gamybos atliekos - glicerolio, medienos drožlių plok&scaron;čių pjuvenų ir organinio sapropelio. Keramzito izoliacinės savybės gerėja didėjant i&scaron;degto molio &scaron;ukės akytumui. Kad molis pūstųsi geriau, į jį dažnai įmai&scaron;oma organinių priedų. Tirtas Krūnos telkinio III sluoksnio karbonatingasis molis be priedų netinka keramzito gamybai dėl per mažo i&scaron;sipūtimo koeficiento (<em>K_p</em>&nbsp;=&nbsp;1,25). Tam tikslui į i&scaron;džiovintą smulkiai maltą molį buvo įmai&scaron;oma įvairūs kiekiai (0&nbsp;%, 1&nbsp;%, 2&nbsp;%, 3&nbsp;%, 5&nbsp;%, 7&nbsp;% ir 10&nbsp;%) organinių atliekų. Granulės gamintos su vienu arba keliais pasirinktais degimo metu dujas i&scaron;skiriančiais priedais. Suformuotos ir i&scaron;džiovintos granulės degtos skirtingose temperatūrose iki jų apsilydimo temperatūros - nuo 1090_&nbsp;&deg;C iki 1170_&nbsp;&deg;C. Nustatytas i&scaron;degtų granulių pūtimasis ir vandens įmirkis. Tyrimų metu nustatyta, kad organinės atliekos yra efektyvus priedas, didinantis molio struktūros akytumą. Be to, molyje neturi būti daugiau kaip 5&nbsp;% sapropelio, rekomenduojamas glicerolio kiekis yra 1&nbsp;%_&nbsp;-_&nbsp;3&nbsp;%, optimalus pjuvenų kiekis - 3&nbsp;%. Bandinių, pagamintų su nurodytais priedų kiekiais ir i&scaron;degtų skirtingose temperatūrose, vandens įmirkis nevir&scaron;ija 15 %.<p><a href="http://dx.doi.org/10.5755/j01.ms.17.3.600">http://dx.doi.org/10.5755/j01.ms.17.3.600</a></p

Saulės energijos naudojimo galimybės automatinės telekomunikacijų stoties mikroklimato sistemoje

Vytauto Didžiojo universitetasŽemės ūkio akademij

Posibilities of solar energy use for automatic telecommunication stations

Šiame darbe atlikti elektros energijos poreikių tyrimai konteinerinio tipo automatinėje telekomunikacijų stotyje (ATS). įrengtoje kaimo vietovėje. Tyrimų metu nustatyta, kad ATS įranga per metus sunaudoja apie 6582 kWh elektros energijos, iŠ kurios apie 24 % (1550 kWh) sunaudojama įrangos kondicionavimui. Tyrimais nustatyta, kad elektros energijos suvartojimas tiesiškai priklauso nuo aplinkos oro temperatūros. Ištyrus ATS elektros energijos vartojimo ir saulės energijos kaitos dinamiką statistiniais metodais, nustatyta, kad šiuos poreikius galima tenkinti naudojant konvertuotą saulės energijąThis paper is dedicated for analysis of the electrical energy consumption on the automatic station of telecommunications situated in the rural area. It is determined that all equipment of such station consumes per year about 6582 kWh of electrical energy. About 24 % (1550 kWh) of this amount was consumed for conditioning of the equipment. It was found the linear correlation between energy demand and ambient temperature of the station. Furthermore regarding statistical distribution of solar irradiance was found linear con-elation between energy demand on the station and possible solar electricity generationVytauto Didžiojo universitetasŽemės ūkio akademij

Automatinės telekomunikacijų stoties elektros energijos sąnaudų tyrimas

Electricity consumption researches were done in automatic station providing telecommunications services in rural areas. Research have shown that ATS equipment annually consumes about 6582 kWh of electricity, of which about 33% (2176 kWh) consumes microclimate equipment. Experimentally measured that the telecommunications equipment of electricity consumption throughout the year mediates little. While electric power consumption of the microclimate system depends on the ambient air temperatureVytauto Didžiojo universitetasŽemės ūkio akademij

Possibilities to use photoelectric energy sources in microclimate system of telecommunication station

Communication services in Lithuanian villages are rendered with the help of container type automated telecommunication stations (ATS). Backup automated electric power supply systems are installed in these stations, but ATS equipment is powered from the electrical network. The investigations disclosed that ATS equipment uses approximately 6582 kWh of electric power the 33 % of which (2176 kWh) is consumed by microclimate equipment. Thus, trying to minimize the electric energy amount taken by ATS equipment from the electrical networks the possibilities to meet the electric power demand of the microclimate system of ATS equipment are analyzed using the solar photoelectric power sources. The tests showed that the electric energy consumption in ATS microclimate system depends on the ambient air temperature the change of which in the course of the year depends on the quantitative variations of solar energy striking the land surface. The investigation of the dynamics of solar energy variations and the electric power consumption of the ATS microclimate system showed that the demands of the electric power consumption of the ATS microclimate system can be met using the converted solar energyVytauto Didžiojo universitetasŽemės ūkio akademij

Sapropelis keramzito gamyboje

Tirtos organinio sapropelio panaudojimo galimybės keramzito gamyboje naudojant mažai besipučiančius ir nesipučiančius vietinius molius. Nustatyta, kad geriausiai nekarbonatingi molio su sapropelio priedu bandiniai pūtėsi esant 1070-1130 °C temperatūrai, o karbonatiniai - tik esant 1150 ± 10 "C temperatūrai. Geriausių pūtimosi savybių mišiniai gauti iš nekarbonatinio molio su 3-5 % organinio sapropelio. Jie pūtėsi esant 80 °C, kai Kpv = 3,36-3,42. Molio pūtimasis priklauso ne tik nuo sapropelio priedo kiekio, bet ir nuo molyje esančių karbonatų kiekio, kurie mažina pūtimąsi. Tirti moliai be degių priedų beveik nesiputė. Bandytas degus organinio sapropelio priedas pagerino molio pūtimosi savybes ir pažemino jo pūtimosi bei lydymosi temperatūrąIn the paper the possibility of the use of organic sapropel for expanded clay production, by using of low self expanding and non-self expanding local clays, is investigated. The sample with not carbonate clay and sapropel addition the best expands in 1070−1130oC temperature range, and that of carbonate clay – in a very narrow 1150 ± 10 temperature ranges. Mixtures of the best expanding properties contain not carbonate clay and 3−5% of organic sapropel. They expand in 80°C temperature range, at Kpv = 3.36−3.42. The clay expanding depends not only on the sapropel quantity, but also on the carbonate content, which reduces expansion. The investigated clays without flammable additives do not expand. The tested flammable organic sapropel addition improves clay expanding properties and downgrades the bloating and melting temperaturesVytauto Didžiojo universitetasŽemės ūkio akademij