Statybinių kompozitų su pluoštinių kanapių spaliais tyrimai

Disertacijoje nagrinėjama ekologiškų kompozitų, kuriuose kaip užpildai naudojami pluoštinių kanapių (Canabis Sativa L) spaliai (PKS), savybės. Pagrindiniai tyrimo objektai yra pluoštinių kanapių spaliai, rišikliai tokie kaip cementas, molis, kalkės, krakmolas, sapropelis, taip pat kompozito, susidedančio iš PKS ir minėtųjų rišiklių savybės. Pagrindinis disertacijos tikslas sukurti formavimo mišinio sudėtį bei technologiją ekologiškam daugiafunkciniam kompozitui. Disertaciją sudaro įvadas, trys skyriai, bendrosios išvados, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašai. Pirmasis skyrius skirtas literatūros apžvalgai. Jame pateikta bendra informacija apie kompozitus, pluoštinių kanapių perdirbimo, panaudojimo galimybių analizė. Šiame skyriuje pateikta bendra informacija apie pluoštinę kanapę, jos panaudojimas pramonėje, konkrečiai statybos sektoriuje, apžvelgtos jos savybės. Apžvelgta literatūra susijusi su tyrimams naudotais rišikliais, detaliau išanalizuota cementinis rišiklis, bei procesai vykstantys jo rišimosi metu. Šiame skyriuje išanalizuotos kompozitų, kuriuose kaip užpildas naudoti pluoštinių kanapių spaliai, savybės. Skyriaus pabaigoje pateiktos literatūrinės apžvalgos išvados ir disertacijos uždaviniai Antrajame skyriuje aprašytos tyrimams naudotos medžiagos, pateiktos pagrindinės jų charakteristikos. Taip pat aprašyti taikyti tyrimų metodai ir naudota įranga. Trečiajame skyriuje pateikta pluoštinių kanapių spalių (PKS) užpildo savybių tyrimų rezultatai bei struktūros analizė. Ištirtas kompozitas su sapropelio rišikliu, nustatyta rišiklio kiekio, užpildo granuliometrijos, technologinių parametrų, tokių kaip formavimo mišinio apspaudimo lygis, priedų (armuojančiojo priedo bei hidrofobizuojančiojo priedo) poveikis kompozito fizikinėms bei mechaninėms savybėms bei ištirta kompozito mikro struktūra. Ištirtos kompozito su cementiniu rišikliu fizikinės mechaninės savybės bei struktūra, parinkti racionalūs mineralizuojančiojo bei plastifikuojančiojo priedų kiekiai, atlikti rentgentografiniai tyrimai. Disertacijos tema paskelbti 5 straipsniai: vienas Thomson Reuters Web of Science duomenų bazėje bei turintis cituojamumo rodiklį, du – straipsnių rinkiniuose, įtrauktuose į Thomson Reuters duomenų bazę, vienas – recenzuojamoje tarptautinės konferencijos medžiagoje bei vienas – respublikinės konferencijos medžiagoje. Disertacijos tema perskaityti 8 pranešimai Lietu-vos bei kitų šalių konferencijose

The impact of chain extender on the properties of polyurethane foam based on rapeseed oil polyol obtained via chemo–enzymatic route

Presently, researches regarding green chemistry are conducted due to its significance for the mitigation of environmental problems, particularly those related to carbon dioxide emissions in relation to global warming and the usage of fossil feedstocks not only for energy generation but also for materials production. The study examines the impact of bio-products such as corn starch, rapeseed glycerin as well as petroleum based propylene glycol as bifunctional and trifunctional chain extenders on physical-mechanical properties of polyurethane foam from rapeseed oil polyol derived via chemo-enzymatic route. The obtained foams were characterized using European and international methodologies for determination of density, compressive strength perpendicular and parallel to foaming directions, thermal conductivity, long-term water absorption after 28 days of immersion, closed cell content and cell size. Foams containing (5–25) pphp of corn starch display significantly lower values in density and compressive strength as well as cell size compared to the neat polyurethane foam. The greatest compressive strength and the lowest thermal conductivity are obtained for foams with 25 pphp of rapeseed glycerin. All foams extended with bio-products and propylene glycol are characterized by the higher long-term water absorption compared to that of the neat polyurethane foam

Influence of SiO2 microdust to gas cement concrete with mixed binding material strength characteristics

Autoklavinių akytųjų betonų (AAC) gamybos metu naudojant tam tikras gamybos atliekas galima pagerinti jo stiprumines savybes. Gamybos atliekos naudojamos pakankamai mažais kiekiais ir jų kaina nėra didelė, todėl galima pagerinti AAC stiprumines savybes pakankamai mažomis išlaidomis. Šiame darbe tirtas SiO2 mikrodulkių (SM) poveikis AAC, su mišria rišamąja medžiaga, stipruminėms savybėms. Tirti keturių sudėčių bandiniai: kontrolinis (be SM priedo), su 0,5 % SM, su 1,0 % SM ir su 1,5 % SM. Darbe aprašyta sudėties skaičiavimo bei bandinių formavimo metodika. Pateikti gniuždymo stiprio rezultatai,gauti atlikus gniuždymo stiprio bandy-mą (buvo gniuždomi 70x70x70 mm bandiniai) presu. Pagal standartą LST 1469, naudojant gautus gniuždymo stiprio rezulta-tus, pagal empirines lygtis, apskaičiuotos lenkimo stiprio bei tempimo stiprio reikšmės. Gauti eksperimentiniai rezultatai apdoroti programa „STATISTICA“ ir gauta gniuždymo stiprio priklausomybė nuo tankio bei SM priedo kiekio.Santrauka anglų kalba. Using certain production wastes can be improved strength cha-racteristics of autoclaved cellular concrete (AAC). Since pro-duction wastes are used in sufficiently small quantities and their price is not high, it is possible to improve strength characteris-tics of AAC in sufficiently low cost. In this work the impact of silica fume on strength characte-ristics of AAC with composite binder material was investigated. There were samples of four compositions: comparative (without ANS), with 0,5% ANS, with 1,0% ANS and with 1,5% ANS. In this article composition calculation and formation methods of samples are described. Compressive strength results obtained by compressing samples (70 mm x 70 mm x 70 mm. Bending strength and tension strength values were calcula-ted according to standard LST 1469 using received compressive strength results. Results were processed with programme STATISTICA and it was obtained the dependence on compres-sive strength of density and amount of ANS supplement

Studies on the thermal conductivity of composite materials based on local renewable resources

Thermal insulation materials produced from local renewable resources are increasingly used for two reasons – they are environmentally friendly and their manufacture requires less amount of energy. The most renewable resources include a wide variety of crop straw – barley, rye, wheat, triticale, etc. the thermal conductivity of which depends on their orientation to the product and structure of the same straw. For specimen composition, the straw stems of bulrush, reeds, bent and triticales were used, producing composites with the mass ratio of 1:1. The paper analyses the results of thermal conductivity tests on different stem composites of herbaceous plants. Thermal conductivity was investigated considering composition specimens such as bulrush-reeds, bulrush-bent, bulrush-straw, reed-straw, reed-bent. The use of composites in all cases reduced thermal conductivity compared with the thermal conductivity of materials used alone. The greatest reduction in thermal conductivity compared with the thermal conductivity of the single straws of herbaceous plants has been observed in bulrush-straw composites. Article in Lithuanian. Kompozicinių termoizoliacinių medžiagų iš vietinių atsinaujinančių išteklių šilumos laidumo tyrimai Santrauka. Termoizoliacinės medžiagos iš vietinių atsinaujinančių išteklių vis plačiau naudojamos dėl dviejų priežasčių – jos yra ekologiškos ir jų gamybai reikalingi maži energijos kiekiai. Iš atsinaujinančių išteklių labiausiai paplitę įvairių kultūrinių augalų šiaudai: miežių, rugių, kviečių, kvietrugių ir kt. Šių medžiagų šilumos laidumas labiausiai priklauso nuo jų orientacijos gaminyje ir pačių stiebelių struktūros. Bandiniams komponuoti buvo naudojama švendrų, nendrių, smilgų ir kvietrugių šiaudų stiebai, iš kurių pagal masės santykį 1:1 buvo komponuojami kompozitai. Atlikta kompozitų, sudarytų iš skirtingų žolinių augalų stiebelių, šilumos laidumo tyrimai. Tirti tokių sudėčių bandinių šilumos laidumai: švendrai + nendrės, švendrai + smilgos, švendrai + šiaudai, nendrės + šiaudai, nendrės + smilgos. Naudojant kompozitus visais atvejais sumažintas šilumos laidumas lyginant su šilumos laidumu, kai naudotos pavienės medžiagos: didžiausias šilumos laidumo sumažėjimas, lyginant su pavienių augalų stiebų šilumos laidumu, gautas švendrų ir šiaudų kompozite. Raktiniai žodžiai: vietiniai atsinaujinantys ištekliai, kompozitinės termoizoliacinės medžiagos, šilumos laidumas, makrostruktūra

Rapeseed-based polyols and paper production waste sludge in polyurethane foam: Physical properties and their prediction models

Intervention into the present building industry is the main strategy of the European Commission in order to achieve one of its planned aims regarding the reduction of greenhouse gas emissions up to 20% up by 2020 and up to 80% by 2050. Therefore, it is necessary to develop not only energetically efficient but also more environmentally friendly materials. This work presents bio-based propylene glycol and paper waste sludge particles modified polyurethane foams, their physical properties and their prediction models. The conducted research has revealed that paper waste sludge particles negatively affect dimensional changes. In order to eliminate the negative impact of paper waste sludge, bio-based propylene glycol is used. The obtained results have shown that this raw material allows development of dimensionally and structurally stable polyurethane foams used as a thermal insulating layer having the following properties: density in the range of 40–50 kg/m3 , compressive strength in the range of 193–243 kPa, thermal conductivity in the range of 0.0349–0.0359 W/(m·K), long-term water absorption in the range of 6–11 vol.% and water vapour transmission factor in the range of 26.2–40.9. On the basis of the results, prediction models are suggested for the most important physi

Assessment of structure influence on thermal conductivity of hemp shives composite

In past ten years area of green technologies and materials was the most growing industry sector in the world. It is related wit h global warming, air pollution and energy saving. Building sector intensively increased air pollu tion and is related with high energy consumptions. The use of renewable or recyclable materials can reduce these problems. In current work, thermal insulating materials from hemp shives and corn starch were investigated. Structures of various shives fractions were analyzed. Different sized shives by two indi cators bulk density and thermal conductivity were compared. Composite materials with various shives fractions and corn st arch were prepared. Different thermal treatment for composite hardening was used. Thermal conductivity and compressive strength of composites were determined. Thermal insulating composites with a high compressive strength and low thermal conductivity were developed

Physical Properties and Structure of Composite Made by Using Hemp Hurds and Different Binding Materials

AbstractMaximum power consumption comes to building heating, which depends on the efficiency of building envelopes. Energy consumption of building sector covers 50% of the total energy consumption. Reducing building energy cost it is necessary to increase the energy efficiency of complex elements in envelopes, both in their production and operational conditions. The usage of plant-based materials such as hemp hurds, which has high porosity and porous structure, increases efficiency of envelopes, reduces production cost, relatively reduces the emission of CO2, because, in order to perform photosynthesis, plants absorb CO2 and release oxygen. This feature is very important ecologically and it is increasingly important factor for humanity. This paper covers the composite materials of the hemp hurds and different binders such as cement, clay, starch. The compressive strength, thermal conductivity dependence on density and microstructure of various compositions composites were investigated

Impact of hemp shives aggregate mineralization on physical–mechanical properties and structure of composite with cementitious binding material

This article analyses the possibility of fibre hemp shives (FHS) to be used as lightweight aggregate in composite with cement binding material. Cement and plant origin aggregates are hardly compatible, because water-soluble or alkaline environment soluble compounds inhibit cement hydration. To avoid harmful effect on cement hydration, it is necessary to mineralize FHS aggregates with complex mineralizer (which consists of Al2(SO4)3 and Ca(OH)2) in order to minimize the impact of hydration retarders on cement hydration. Rational amount of super plasticizer for forming mixture is selected in accordance with viscosity of cement paste. Amount and ratio of mineralizer was selected according to kinetics of hydration temperature of forming mixture, compressive strength, ultrasonic pulse velocity (UPV). It was determined that the increase in the amount of mineralizer from 27% to 54 % (estimated based on FHS mass) promotes the cement hydration, shortens the time needed to reach EXO maximum and increases its temperature, because the higher content of the Ca(OH)2 participates in the process of dissolution and makes the EXO reaction faster. The highest acceleration of cement hydration in a composite sample is caused by optimum amount of component mineralizer which is 54%. The lower content of component mineralizer did not completely bind sugar released from FHS, therefore, causing inhibition of cement hydration. Optimal amount and ratio of mineralizer allow obtaining the compressive strength after 28 days of curing of 8.03 MPa as well as thermal conductivity of 0.179 W/(m K). Microstructure analyses show that cement matrix with optimal amount of complex mineralizer is dense enough and well bonded with new monolithic hydration products

Development of Thermal Insulation from Local Agricultural Waste

In Lithuania yearly composes large quantity of waste during processing of agricultural plants. Large quantity of these waste amounts a straw. A small part of straw is used for biofuel, the remaining part of straw is chopped and injected in the soil. Purpose of this work is to explore possibilities for production of effective insulation material from straw. In this paper assessment of straw structure and technological factors on the thermal conductivity are presented. For the experiments straw of triticale were used. Thermal conductivity with different straw orientation and structure were measured. It was found that in the laboratory prepared samples has approximately 1.5 times lower thermal conductivity, in which majority of straw are oriented perpendicular to heat flow, than plant specimens prepared from straw bale and roll, in which majority of the straw are oriented parallel to heat flow. It was observed that increasing the density of loose straw thermal conductivity increases too, while thermal conductivity of chopped straw remains stable or declines slightly

The Impact of Microorganisms on the Performance of Linseed Oil and Tung Tree Oil Impregnated Composites Made of Hemp Shives and Corn Starch

In this study, the performance characteristics of hemp shives impregnated with linseed oil and tung tree oil (HS)- and corn starch (CS)-based biocomposites containing flame retardants were evaluated before and after treatment with the mixture of bacterium Pseudomonas putida and fungus Rhizopus oryzae. Enzymatic activities and physical-mechanical properties such as water absorption, thickness swelling, compressive strength, and thermal conductivity were tested to evaluate the suitability of selected composites for thermal insulation purposes. In addition, electron microscopy was used to investigate the impact of microorganisms on the microstructure of the material. It was determined that the type of oil used for impregnation significantly affects the properties of biocomposites after 6 months of incubation with mixture of bacterium P. putida and fungus Rh. oryzae. Biocomposites impregnated with linseed oil and after treatment with a mixture of microorganisms had cellulase activity of 25 U/mL, endo β-1-4-glucanase activity of 26 U/mL, lipase activity of 101 U/mL, only a 10% decrease in compressive strength, 50% higher short-term water absorption, unchanged swelling in thickness, and slightly decreased thermal conductivity compared to control biocomposites. At the same time, biocomposites with tung tree oil had a much more pronounced deterioration of the properties tested, cellulase activity of 28 U/mL, endo β-1-4-glucanase activity of 37 U/mL, lipase activity of 91 U/mL, two times lower compressive strength and two times higher short-term water absorption, 2.5 times greater thickness swelling, and a slightly increased thermal conductivity. We conclude that linseed oil provides better protection against the action of microorganisms compared to impregnation with tung tree oil