Super High Strength Metabentonite Based Geopolymer

AbstractThe paper presents the results of the study on the effects of the combination of the low liquid/solid (l/s) ratio and pressure compaction of the fresh pastes on the properties of the hardened based geopolymer paste. It is very well known that the mentioned combination gives the possibility to prepare cement composites with the excellent engineering properties. The object of the study was the metabentonite based geopolymer. The results obtained shown the metabentonite based geopolymer prepared under the combination of the low l/s ratio value and pressure compaction as a super strength material. This strength effect was evidently a consequence of the found high dense nano- or near-nano pore structure of the geopolymer

Uticaj azota i sorte na prinos i kvalitet zrna soje

The effects of the application of increased ratios of nitrogen on the grain yield and quality of soya bean cultivars of different maturity groups were studied. The three-year study was conducted in the experimental field located in southern Banat. The soil belongs to the chernozem type with optimum physical and chemical properties. The cultivars Sava, Valjevka, Proteinka Diva, Venera and Mima were used in this study. The system of top dressing of plants with nitrogen included the following ratios of nitrogen: 50 kg ha-1 (N1), 100 kg ha-1 (N2) and 150 kg ha-1 (N3). The control variant did not include top dressing with nitrogen (N0). Field experiments were set up according to the split-plot system with four replications. The results showed that all six cultivars had high genetic potential, which did not significantly increase with increasing ratios of nitrogen. Grain yield was the highest in a year with the most favourable distribution of rainfall (2007). The total protein content in grain was important for the research, cultivars and nitrogen ratios. The oil synthesis and accumulation in grain were mainly influenced by weather conditions during the experiments, cultivars, while nitrogen had no effect on this indicator of quality. .Ispitivana je primena povećane količine azota u tri varijante ishrane na prinos i kvalitet zrna sorti soje različitih grupa zrenja. Trogodišnja istraživanja su izvedena na oglednom polju koje se nalazi na području južnog Banata. Zemljište je bilo tipa černozem optimalnih fizičkih i hemijskih svojstava. Predmet ovih istraživanja bili su sorte sava, valjevka, proteinka, diva, venera i mima. Sistem dopunske ishrane biljaka azotom obuhvatio je sledeće količine azota: 50 kg ha-1 (N1), 100 kg ha-1 (N2) i 150 kg ha-1 (N3). Kontrolna varijanta je bila bez dopunske ishrane azotom (N0). Poljski mikroogledi soje postavljeni su metodom razdeljenih parcela (split-plot), u četiri ponavljanja. Rezultati istraživanja pokazali su da svih šest sorti imaju visok genetički potencijal rodnosti, koji se nije značajno povećavao sa rastućim količinama azota. Prinos zrna soje bio je najviši u 2007, godini sa najpovoljnijim rasporedom padavina. Sadržaj ukupnih proteina u zrnu bio je značajan za godine istraživanja, sorte i količine primenjenog azota. Na sintezu i nakupljanje ulja u semenu najveći uticaj ispoljili su vremenski uslovi tokom izvođenja ogleda, sorte, dok azot nije imao uticaj na ovaj pokazatelj kvaliteta.

Effect of nanosilica-based activators on the performance of an alkali-activated fly ash

This paper assesses the effect of the use of an alternative activator based on nanosilica/MOH (M = K+ or Na+) blended solutions on the performance of alkali-activated fly ash binders. Binders produced with commercial silicate activators display a greater degree of reaction, associated with increased contents of geopolymer gel; however, mortars produced with the alternative nanosilica-based activators exhibited lower water demand and reduced permeability, independent of the alkali cation used. Na-based activators promote higher compressive strength compared with K-based activators, along with a refined pore structure, although K-activated samples exhibit reduced water demand. Zeolite type products are the major crystalline phases formed within these binders. A wider range of zeolites is formed when using commercial silicate solutions compared with the alternative activators. These results suggest that there are variations in the availability of Si in the system, and consequently in the alkalinity, depending on the silicate source in the activator, which is important in determining the nanostructure of the geopolymer gel.This study was sponsored by the Ministerio de Ciencia e Innovacion of Spain (Project GEORES MAT2010-19934 and research scholarship BES-2008-002440), European regional development fund (FEDER), and the Universitat Politecnica de Valencia (Spain). The participation of SAB and JLP was funded by the Australian Research Council (ARC), including partial funding through the Particulate Fluids Processing Centre, a Special Research Centre of the ARC. A special acknowledgement is also due to the Centre of Electron Microscopy of the Universitat Politecnica de Valencia and Pedro Garces from the Universidad de Alicante for support in some experiments.Rodriguez Martinez, ED.; Bernal, SA.; Provis, JL.; Paya Bernabeu, JJ.; Monzó Balbuena, JM.; Borrachero Rosado, MV. (2013). Effect of nanosilica-based activators on the performance of an alkali-activated fly ash. Cement and Concrete Composites. 35(1):1-11. doi:10.1016/j.cemconcomp.2012.08.025S11135

Effect of the activator dose on the compressive strength and accelerated carbonation resistance of alkali silicate-activated slag/metakaolin blended materials

The effects of activator dose on the properties of alkali-activated slag/metakaolin blends, were studied in fresh and hardened states: heat evolution, strength and accelerated carbonation. High activator concentrations affect the slag dissolution rate, reducing compressive strength when this is the sole precursor. An increased activator concentration favours metakaolin reaction, promoting high strengths and reduced permeability. Metakaolin addition, and increased activator concentrations reduce the susceptibility to carbonation, associated with the refinement of the pore network under extended CO2 exposure. The effect of adding an aluminosilicate precursor to an alkali-activated slag system is strongly dependent on the activator concentration

Constructivist Didactics in Combined Classes

Danas se učitelji tijekom studija pripremaju isključivo za rad u klasičnim, tzv. čistim razrednim odjelima. Rad u kombiniranim odjelima spominje se tek povremeno. Zato nastaje problem kada mladi učitelji dobiju prvi posao u kombiniranom odjelu. Kombinirani razredni odjeli formiraju se većinom u seoskim sredinama gdje nema dovoljno učenika za čiste odjele. Tako se formira odjel od učenika dvaju, triju ili četiriju razreda koje vodi jedan učitelj. Cilj ovog rada bio je opisati specifičnosti rada u kombiniranom razrednom odjelu, a koji se temelji na načelima konstruktivističke didaktike. Konstruktivistička didaktika podrazumijeva aktivnost i samostalnost učenika koji sam gradi svoje znanje na temelju iskustva te kritički promišlja o onome što uči. Konstruktivistička nastava suprotstavljena je tradicionalnoj, predavačkoj nastavi koja je usmjerena na učitelja te pretvara učenika u pasivni objekt. U ovom radu nastojalo se akcijskim istraživanjem pokazati provođenje konstruktivističkih načela u kombiniranom razrednom odjelu. Istraživanje je provedeno u maloj područnoj školi u Grabovnici s učenicima kombinacije drugog i četvrtog razreda. Došlo se do zaključka da nastava u kombiniranim odjelima zbog svojih specifičnosti (izmjena posrednih i neposrednih oblika rada) zahtijeva provođenje konstruktivističkih načela. U kombiniranim odjelima nastava mora biti dinamična, moramo poticati aktivnost svakog učenika i njihovu međusobnu suradnju. Sve navedeno podrazumijeva puno pripreme za učitelja, koji preuzima ulogu organizatora i mentora. Na taj način postiže se zainteresiranost i aktivnost učenika koji školu ne shvaćaju kao mjesto gdje moraju slušati učitelja i upamtiti činjenice kako bi ih kasnije mogli reproducirati.Nowadays teachers are being prepared to work exclusively in classical, so-called pure classes. Working in the combined classes is mentioned only occasionally. That is why there is a problem when young teachers get their first job in a combined department. Combined classes are formed mostly in rural areas where there is not enough pupils for pure classes. For that reason, a department of two, three or four classes is led by one teacher. The aim of this paper was to describe the specifics of working in a combined class, based on the principles of constructivist didactics. Constructivist didactics implies the activity and autonomy of the student who builds his own knowledge based on experience and critically reflects on what he is learning. Constructivist teaching is opposed to the traditional lecturer-oriented teaching, which turns the student into a passive object. In this paper, the aim of the research was to demonstrate the implementation of constructivist principles in the combined class. The research was conducted in a small regional school in Grabovnica with students of the second and fourth class combination. It was concluded that teaching in combined departments because of their specificity (alteration of direct and indirect forms of work) requires the implementation of constructivist principles. In combined classes, teaching must be dynamic, we must encourage the activity of each student and their mutual cooperation. All of this implies a lot of preparation for a teacher who takes on the role of organizer and mentor. In this way we encourage the interest and activity of the students who do not take the school as a place where they have to listen to the teacher and remember the facts in order to reproduce them later

Constructivist Didactics in Combined Classes

Danas se učitelji tijekom studija pripremaju isključivo za rad u klasičnim, tzv. čistim razrednim odjelima. Rad u kombiniranim odjelima spominje se tek povremeno. Zato nastaje problem kada mladi učitelji dobiju prvi posao u kombiniranom odjelu. Kombinirani razredni odjeli formiraju se većinom u seoskim sredinama gdje nema dovoljno učenika za čiste odjele. Tako se formira odjel od učenika dvaju, triju ili četiriju razreda koje vodi jedan učitelj. Cilj ovog rada bio je opisati specifičnosti rada u kombiniranom razrednom odjelu, a koji se temelji na načelima konstruktivističke didaktike. Konstruktivistička didaktika podrazumijeva aktivnost i samostalnost učenika koji sam gradi svoje znanje na temelju iskustva te kritički promišlja o onome što uči. Konstruktivistička nastava suprotstavljena je tradicionalnoj, predavačkoj nastavi koja je usmjerena na učitelja te pretvara učenika u pasivni objekt. U ovom radu nastojalo se akcijskim istraživanjem pokazati provođenje konstruktivističkih načela u kombiniranom razrednom odjelu. Istraživanje je provedeno u maloj područnoj školi u Grabovnici s učenicima kombinacije drugog i četvrtog razreda. Došlo se do zaključka da nastava u kombiniranim odjelima zbog svojih specifičnosti (izmjena posrednih i neposrednih oblika rada) zahtijeva provođenje konstruktivističkih načela. U kombiniranim odjelima nastava mora biti dinamična, moramo poticati aktivnost svakog učenika i njihovu međusobnu suradnju. Sve navedeno podrazumijeva puno pripreme za učitelja, koji preuzima ulogu organizatora i mentora. Na taj način postiže se zainteresiranost i aktivnost učenika koji školu ne shvaćaju kao mjesto gdje moraju slušati učitelja i upamtiti činjenice kako bi ih kasnije mogli reproducirati.Nowadays teachers are being prepared to work exclusively in classical, so-called pure classes. Working in the combined classes is mentioned only occasionally. That is why there is a problem when young teachers get their first job in a combined department. Combined classes are formed mostly in rural areas where there is not enough pupils for pure classes. For that reason, a department of two, three or four classes is led by one teacher. The aim of this paper was to describe the specifics of working in a combined class, based on the principles of constructivist didactics. Constructivist didactics implies the activity and autonomy of the student who builds his own knowledge based on experience and critically reflects on what he is learning. Constructivist teaching is opposed to the traditional lecturer-oriented teaching, which turns the student into a passive object. In this paper, the aim of the research was to demonstrate the implementation of constructivist principles in the combined class. The research was conducted in a small regional school in Grabovnica with students of the second and fourth class combination. It was concluded that teaching in combined departments because of their specificity (alteration of direct and indirect forms of work) requires the implementation of constructivist principles. In combined classes, teaching must be dynamic, we must encourage the activity of each student and their mutual cooperation. All of this implies a lot of preparation for a teacher who takes on the role of organizer and mentor. In this way we encourage the interest and activity of the students who do not take the school as a place where they have to listen to the teacher and remember the facts in order to reproduce them later

Constructivist Didactics in Combined Classes

Danas se učitelji tijekom studija pripremaju isključivo za rad u klasičnim, tzv. čistim razrednim odjelima. Rad u kombiniranim odjelima spominje se tek povremeno. Zato nastaje problem kada mladi učitelji dobiju prvi posao u kombiniranom odjelu. Kombinirani razredni odjeli formiraju se većinom u seoskim sredinama gdje nema dovoljno učenika za čiste odjele. Tako se formira odjel od učenika dvaju, triju ili četiriju razreda koje vodi jedan učitelj. Cilj ovog rada bio je opisati specifičnosti rada u kombiniranom razrednom odjelu, a koji se temelji na načelima konstruktivističke didaktike. Konstruktivistička didaktika podrazumijeva aktivnost i samostalnost učenika koji sam gradi svoje znanje na temelju iskustva te kritički promišlja o onome što uči. Konstruktivistička nastava suprotstavljena je tradicionalnoj, predavačkoj nastavi koja je usmjerena na učitelja te pretvara učenika u pasivni objekt. U ovom radu nastojalo se akcijskim istraživanjem pokazati provođenje konstruktivističkih načela u kombiniranom razrednom odjelu. Istraživanje je provedeno u maloj područnoj školi u Grabovnici s učenicima kombinacije drugog i četvrtog razreda. Došlo se do zaključka da nastava u kombiniranim odjelima zbog svojih specifičnosti (izmjena posrednih i neposrednih oblika rada) zahtijeva provođenje konstruktivističkih načela. U kombiniranim odjelima nastava mora biti dinamična, moramo poticati aktivnost svakog učenika i njihovu međusobnu suradnju. Sve navedeno podrazumijeva puno pripreme za učitelja, koji preuzima ulogu organizatora i mentora. Na taj način postiže se zainteresiranost i aktivnost učenika koji školu ne shvaćaju kao mjesto gdje moraju slušati učitelja i upamtiti činjenice kako bi ih kasnije mogli reproducirati.Nowadays teachers are being prepared to work exclusively in classical, so-called pure classes. Working in the combined classes is mentioned only occasionally. That is why there is a problem when young teachers get their first job in a combined department. Combined classes are formed mostly in rural areas where there is not enough pupils for pure classes. For that reason, a department of two, three or four classes is led by one teacher. The aim of this paper was to describe the specifics of working in a combined class, based on the principles of constructivist didactics. Constructivist didactics implies the activity and autonomy of the student who builds his own knowledge based on experience and critically reflects on what he is learning. Constructivist teaching is opposed to the traditional lecturer-oriented teaching, which turns the student into a passive object. In this paper, the aim of the research was to demonstrate the implementation of constructivist principles in the combined class. The research was conducted in a small regional school in Grabovnica with students of the second and fourth class combination. It was concluded that teaching in combined departments because of their specificity (alteration of direct and indirect forms of work) requires the implementation of constructivist principles. In combined classes, teaching must be dynamic, we must encourage the activity of each student and their mutual cooperation. All of this implies a lot of preparation for a teacher who takes on the role of organizer and mentor. In this way we encourage the interest and activity of the students who do not take the school as a place where they have to listen to the teacher and remember the facts in order to reproduce them later