Zaštita Materijala 4. 2021

Third generation biofuels – cultivation methods and technologies for processing of microalgal biofuels

Abstract

Energy production from biomass is gaining a lot of attention. Algal oil (micro- and macroalgae) can be used for biofuel production. Biofuels from this type of feedstock are called third generation biofuels or advanced biofuels. Focus of this paper is on the microalgal biofuels and on the available process technologies. Very important advantage of microalgal biofuels is that microalgae can be cultivated on any type of land, with the possibility of using wastewater streams. Microalgae can be cultivated in open systems, so called “raceway ponds” or in closed systems – photobioreactors: flat panel photobioreactors, horizontal tubular, vertical tubular photobioreactors with or without airlift. Also, basic information on cultivation conditions (photoautotrophic, heterotrophic, mixotrophic and photoheterotrophic) are presented. Available technologies for microalgal biofuels production are: transesterification, fermentation, pyrolysis, hydrothermal liquefaction, anaerobic digestion and biomass to liquids (BtL). Additionally, basic information on life cycle assessment of microalgae cultivation and CO₂ sequestration potential is given in the final chapter of this work.

Keywords: biofuels, microalgae, raceway ponds, photobioreactors, biodiesel, bioethanol.

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Biogoriva treće generacije – procesi uzgajanja i dobijanja goriva iz mikroalgi

Izvod

Istraživanja u vezi sa proizvodnjom energije iz biomase dobijaju sve više pažnje. Ulje iz algi (mikro- i makroalgi) se može koristiti za dobijanje biogoriva. Biogoriva dobijena iz ovog tipa sirovina se nazivaju biogorivima treće generacije ili naprednim biogorivima. Ovaj rad se bazira isključivo na pregledu dostupnih tehnologija dobijanja goriva iz mikroalgi. Bitna prednost uzgoja mikroalgi je upravo ta da su za njihovu kultivaciju pogodni svi tipovi zemljišta, uz mogućnost korišćenja otpadnih tokova. Mikroalge se mogu gajiti u otvorenim sistemima, tzv. “raceway ponds” ili u zatvorenim sistemima, tj. fotobioreaktorima: fotobioreaktori sa ravnim pločama, horizontalni cjevasti, vertikalni stubovi sa ili bez cirkulacione petlje. Kultivacioni uslovi mikroalgi su takođe predstavljeni (fotoautotrofni, heterotrofni, miksotrofni i fotoheterotrofni). Dostupne tehnologije za proizvodnju biogoriva iz ovog tipa sirovina su: transesterifikacija, fermentacija, piroliza, hidrotermalna likvefakcija, anaerobna digestija i konverzija u tečnosti (biomass to liquids – BtL). U zadnjem poglavlju rada su prikazane osnovne informacije o procjeni životnog ciklusa kultivacije mikroalgi, kao i potencijala sekvestracije CO₂.

Ključne riječi: biogoriva, mikroalge, otvoreni sistemi, fotobioreaktori, biodizel, bioetanol.

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Characterisation of biocompatible layers of ZrO₂8%Y₂O used in combination with other ceramics to modify the surface of implants

Abstract

The aim of this study was to deposit multi-functional ZrO₂8%Y₂O₃ coating layers using the plasma spray technology and then to characterise such layers. In combination with other biomedical ceramics, this coating is intended for the application in implant surface modification. The examination was focused on the mechanical properties and microstructure layers . Using the atmospheric plasma spraying, duplex ZrO₂8%Y₂O₃/Ni22Cr10Al1Y coating system was deposited on the X15Cr13 stainless steel, with two different thicknesses of the bond and ceramic coatings. The microstructure was analysed using an optical microscope, including the assessment of the content of micropores. The morphology of powder particles and ceramic coating surfaces were examined on a scanning electron microscope (SEM). The quality of the ZrO₂8%Y₂O₃ layers makes them suitable for the application and combination with other materials to create a system of biomedical or multifunctional coatings.

Keywords: Atmospheric plasma spray, ZrO₂8%Y₂O₃, Ni22Cr10Al1Y, microstructure, interface, microhardness, bond strength.

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Karakterizacija biokompatibilnih slojeva ZrO₂8%Y₂O₃ koji se koriste u kombinaciji sa drugom keramikom za modifikaciju površine implantata

Izvod

Cilj ovog rada bio je da se deponuju višenamenski slojevi prevlake ZrO₂8%Y₂O₃ primenom plazma sprej tehnologije, a zatim da se karakterišu takvi slojevi. U kombinaciji sa drugom biomedicinskom keramikom, ova prevlaka je namenjena primeni u modifikaciji površine implantata. Ispitivanje je bilo usredsređeno na mehanička svojstva i mikrostrukturu slojeva. Korišćenjem atmosferskog plazma spreja, dupleks sistem prevlaka ZrO₂8%Y₂O₃ / Ni22Cr10Al1Y nanet je na nerđajući čelik X15Cr13, sa dve različite debljine vezne i keramičke prevlake. Mikrostruktura je analizirana pomoću optičkog mikroskopa, uključujući procenu sadržaja mikro pora. Morfologija čestica praha i površina keramičkih prevlaka ispitivane su na skening elektronskom mikroskopu (SEM). Kvalitet slojeva ZrO₂8%Y₂O₃ čini ih pogodnim za nanošenje i kombinaciju sa drugim materijalima kako bi se stvorio sistem biomedicinskih ili multifunkcionalnih prevlaka.

Ključne reči: atmosferski plazma sprej, ZrO₂8%Y₂O₃, Ni22Cr10Al1I, mikrostruktura, među­površina, mikrotvrdoća, čvrstoća spoja.

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Balancing of energy flows in a life cycle of thermal energy production from biogas

Abstract

Biogas is a promising source for energy production in future energy systems. In this paper, the energy flows in the life cycle of a real biogas plant (Mirotin-Vrbas) for thermal energy production were considered, starting from corn silage production, cow manure transport, process of anaerobic digestion and biogas production, to the use of solid and liquid digestate for production of crops. Four energy indicators were used to evaluate energy flows in this work. The obtained results showed that this biogas system has a positive energy balance of 62.418 GJ and an energy efficiency of 6,1, which indicates that in terms of substitution of fossil fuel consumption, this system for heat production is a good alternative.

Key words: biogas, heat energy, life cycle, energy, energy efficiency.

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Bilansiranje energetskih tokova u životnom ciklusu proizvodnje toplotne energije iz biogasa

Izvod

Biogas predstavlja obećavajući izvor za dobijanje energije u budućim energetskim sistemima. U ovom radu sprovedeno je razmatranje energetskih tokova u životnom ciklusu realnog biogasnog postrojenja (Mirotin-Vrbas) za proizvodnju toplotne energije, počev od prozvodnje kukuruzne silaže, transporta kravljeg stajnjaka, procesa anaerobne fermentacije i proizvodnje biogasa, do korišćenja čvrstog i tečnog digestata za proizvodnju biljnih kultura. Za evaluaciju energetskih tokova korišćena su četiri energetska indikatora. Dobijeni rezultati su pokazali da ovaj biogasni sistem ima pozitivan energetski bilans od 62.418 GJ i energetsku efikasnost od 6,1 što ukazuje da u pogledu supstitucije potrošnje fosilnih goriva ovaj sistem za proizvodnju toplotne energije predstavlja dobru alternativu.

Ključne reči: biogas; toplotna energija; životni ciklus; energija; energetska efikasnost.

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Inhibition of corrosion of mild steel in well water by an aqueous extract of soapnut (Sapindus Trifoliatus)

Abstract

Inhibition efficiency of an aqueous extract of soapnut (Sapindus Trifoliatus) and Zn²⁺in controlling  corrosion of mild steel in well water at room temperature has been evaluated by using weight loss method, polarization study and AC impedance spectra. Dynamic light scattering and Vickers hardness have also  been employed. Weight loss method reveals that the formulation consisting of 10 ml soapnut extract and 50 ppm Zn²⁺ has 97 % inhibition efficiency in controlling corrosion of mild steel immersed in well water. Synergism parameters suggest that a synergistic effect exists between soapnut extract and Zn²⁺. Adsorption isotherm of metal surface obeys Langmuir adsorption isotherm. Polarization study reveals that the inhibitor system functions as anodic type of inhibitor. AC impedance spectra confirm the protective film formed on the metal surface. Dynamic light scattering (DLS) study reveals surface is in nano meter scale. The Vickers hardness of metal surface was increases in inhibitor system.

Keywords: Sapindus Trifoliatus, corrosion inhibitor, mild steel, well water, dynamic light scattering, Vickers hardness.

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Inhibicija korozije mekog čelika u bunarskoj vodi vodenim ekstraktom sapuna (Sapindus Trifoliatus)

Izvod

Efikasnost inhibicije vodenog ekstrakta sapuna (Sapindus Trifoliatus) i Zn²⁺ u kontroli korozije mekog čelika u bunarskoj vodi na sobnoj temperaturi je procenjena primenom metode gubitka težine, studije polarizacije i spektra impedanse naizmenične struje. Takođe, korišćeno je dinamičko rasejanje svetlosti i tvrdoća po Vikersu. Metoda gubitka težine otkriva da formulacija koja se sastoji od 10 ml ekstrakta sapuna i 50 ppm Zn²⁺  ima 97% efikasnost inhibicije u kontroli korozije mekog čelika uronjenog u vodu iz bunara. Parametri sinergizma sugerišu da postoji sinergistički efekat između ekstrakta sapuna i Zn²⁺. Izoterma adsorpcije metalne površine je podređena Langmuir adsorpcionoj izotermi. Studija polarizacije otkriva da inhibitorni sistem funkcioniše kao anodni tip inhibitora. Spektri impedanse naizmenične struje potvrđuju zaštitni film formiran na površini metala. Studija dinamičkog rasejanja svetlosti (DLS) otkriva da je površina u nanometarskoj skali. Vikersova tvrdoća metalne površine je povećana u sistemu inhibitora.

Ključne reči: Sapindus Trifoliatus, inhibitor korozije, meki čelik, bunarska voda, dinamičko rasejanje svetlosti, tvrdoća po Vikersu.

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Thermal behavior and biological  activity of [Co₂(Cl)₂ tpmc](BF₄)₂  complex

Abstract

A large number of interesting Co (II) complexes with macrocyclicligands have been synthesized and the recognition of its complexes as important bioactive compounds in vitro and in vivo has aroused growing interest in these agents as potential drugs for therapeutic use in various diseases. Numerous available information on their bioinorganic properties and mode of action in several biological systems, combined with the new possibilities imposed by the development of medical chemistry, opens space for the development of a new generation of highly active drugs with minimized side effects which could add significantly to the current clinical research and practice. In this paper we attempt to present some properties of the earlier isolated the first Co(II)tpmc complex for which crystal structure confirmed chair conformation of macrocycle. Complex with formula [Co₂(Cl)₂tpmc](BF₄)₂ (tpmc = N,N¢,N¢¢,N¢¢¢- tetrakis(2-pyridylmethyl)-1,4,8,11 – tetraazacyclotetradecane), was studied on thermal behaviour and biological activity. TG-DTA analysis indicates that complex  decomposition in a single step in the range of 365 -435 °C. Investigated cytotoxic activity against two human cancer cell lines: HeLa (human cervix adenocarcinoma) and K562 (human myelogenous leukaemia). Complex was also preliminary assayed in vitro toward bacteria, fungi and mould together with the starting material for the synthesis (ligands, simple salts and solvents) as test substances. Investigated complex showed a moderate activity against strains of bacteria and were inactive against the tested fungi and mould. Minimal inhibitory concentration suppressing the visible growth of bacteria was determined. Biological investigations show the complex has significant cytotoxic potential.

Key words: Co(II) complex, tpmc, microbiological activity, cytotoxic activity, thermal behavior.

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Termičko ponašanje i biološka aktivnost[Co₂(Cl)₂ tpmc](BF₄)₂ kompleksa

Poznavanje biološke uloge kobalta i prepoznavanje njegovih kompleksa kao važnih bioaktivnih jedinjenja razlozi su sve veće zainteresovanosti za potencijalnu terapijsku primenu ovih kom­pleksa kod različitih bolesti. Brojne dostupne informacije o njihovim osobinama i načinu delovanja u nekoliko bioloških sistema, u kombinaciji sa novim mogućnostima koje nameće razvoj medi­cinske hemije, otvaraju prostor za razvoj nove generacije visoko aktivnih lekova sa minimalnim nuspojavama. U ovom radu smo ispitali neke osobine ranije izolovanog Co (II) tpmc kompleksa, prvog kod koga je rendgenska strukturna analiza potvrdila da se makrciklični ligand nalazi u konformaciji stolice. Ispitivane su termogravimetrijske I biološke osobine kompleksa [Co₂(Cl)₂tpmc](BF₄)₂ (tpmc = N, N´, N´´, N´´´-tetrakis (2-piridilmetil) -1,4,8,11-tetraazaciklo­tetradekan). TG-DTA analiza ukazuje da je razlaganje kompleksa u jednom koraku u rasponu temperature od 365 -435 ° C. Ispitivana je citotoksična aktivnost na dve ljudske ćelijske linije karcinoma: HeLa (adenokarcinom grlića maternice) i K562 (mijelogena leukemija). Antimikrobno djelovanje kompleksa kvantifikovano je određivanjem minimalne inhibitorne koncentracije (MIC) korišćenjem bakterija Staphylococcus saprophyticus, Staphylococcus xylosus, Bacillus cereus, soja kvasca Candida albicans i plesni Aspergillus niger. Biološka ispitivanja su pokazala da kompleks ima značajan citotoksični potencijal I umerenu aktivnost prema bakterijama soja Staphylococcus.

Ključne reči: Co(II) kompleks, tpmc, mikrobiološka aktivnost, citotoksičnost, termička stabilnost

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Antimicrobial properties of copper and its alloys through the prism of the current SARS CoV-2 pandemic

Abstract

Copper has long been known as a metal with outstanding antimicrobial properties. Although ancient healers were not familiar with the mechanisms of its influence on microorganisms, they had empirically established its effectiveness in sterilizing drinking water, disinfecting wounds, treating skin diseases, various infections and other maladies. Recently, there has been renewed interest in investigating copper and its alloys as possible materials that can limit the spread of bacteria and viruses, given that humanity is often facing various local epidemics, and rarely pandemics, as ongoing Corona virus, SARS CoV-2, first detected in March 2020. This paper reviews the recent literature in the research field of antimicrobial properties of metallic copper, its alloys and other copper – based materials, with the aim to promote their future implementation on contact surfaces, primarily in hospitals and institutions with a high frequency of people where the probability of spreading infection is increased.

Keywords: biocidal properties, copper, contact killing, microbes, SARS CoV-2.

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Antimikrobna svojstva bakra i njegovih legura kroz prizmu aktuelne pandemije SARS CoV-2

Izvod

Bakar je od davnina poznat kao metal sa izvanrednim antimikrobnim karakteristikama. Iako drevni iscelitelji nisu poznavali mehanizme njegovog delovanja na mikroorganizme, iskustveno su ustanovili njegovu efikasnost u sterilizaciji vode za piće, dezinfekciji rana, lečenju kožnih oboljenja, različitih infekcija i drugih bolesti. U novije vreme se ponovo javlja interesovanje za ispitivanje bakra i njegovih legura kao mogućih materijala koji mogu ograničiti širenje bakterija i virusa, s obzirom da se čovečanstvo učestalo suočava sa različitim epidemijama lokalnog karaktera, a povremeno, kao od marta 2020. godine, sa pandemijom korona virusa SARS CoV-2. U radu je dat pregled novije literature u istraživanju antimikrobnih svojstava bakra, njegovih legura i drugih materijala na bazi bakra, u cilju buduće implementacije na dodirnim površinama prvenstveno u bolnicama i ustanovama sa visokom frekvencijom ljudi gde je povećana verovatnoća širenja zaraze.

Ključne reči: biocidna svojstva, bakar, kontaktno ubijanje, mikrobi, SARS CoV-2.

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Inhibition of corrosion of mild steel by an alcoholic extract of a seaweed Sargassum muticum

Abstract

An alcoholic extract of a sea weed Sargassum muticum  has been used to control corrosion of mild steel in 0.5 N HCl. Weight loss method and Electrochemical studies have been used in this study. Weight loss study reveals that 500 ppm of the inhibitor offers  99.25  % inhibition efficiency. Polarization study reveals that the inhibitor functions as an anodic inhibitor at higher concentration. The AC impedance spectra confirm the formation of a protective film on the  metal surface. Adsorption of inhibitor molecules on the metal surface follows Langmuir adsorption isotherm.

Keywords: corrosion inhibition, mild steel, sea weed, Sargassum muticum, electrochemical studies, Langmuir adsorption isotherm, acid medium

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Inhibicija korozije mekog čelika alkoholnim ekstraktom algi sargassum muticum

Izvod

Alkoholni ekstrakt morske trave Sargassum muticum korišćen je za kontrolu korozije mekog čelika u 0,5N HCl. U ovoj studiji su korišćene metode gubitka težine i elektrohemijske studije. Studija gubitka težine otkriva da 500 vodppm inhibitora daje 99,25 % efikasnost inhibicije. Studija polarizacije otkriva da inhibitor funkcioniše kao anodni inhibitor u većoj koncentraciji. Spektar impedanse naizmenične struje potvrđuje stvaranje zaštitnog filma na površini metala. Adsorpcija molekula inhibitora na površini metala prati Langmuirovu izotermu adsorpcije.

Ključne reči: inhibicija korozije, meki čelik, morski korov, Sargassum muticum, elektrohemijske studije, Langmuirova izoterma adsorpcije, kiseli medijum

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Synthesis of two supramolecular coordination polymers and electrochemical evaluation of their corrosion inhibition performance on corrosion of Carbon Steel in Acidic medium

Abstract

The effect of the SCPs-[Cu^II(en)₂] [Cu^I(CN)₂]₂. H₂O] (SCP1) and {[H₂DAB] [Cu₄(CN)₆].2H₂O} (SCP2) as corrosion inhibitors for carbon steel (CS) was studied in 1.0M HCl solution. As the synthesized inhibitor dose increases, the inhibition productivity (%η) increases reaching to 90.3% and 89.9% at 21×10^-6M dose for SCP2 and SCP1, respectively. This result evidenced by mass loss (ML) investigated at three different temperatures 25-35-45^oC, while potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS), and electrochemical frequency modulation technique (EFM) were tested at 25°C. The synthesized inhibitors adsorbed on the CS surface physically allowing Henry isotherm. The results displayed that the synthesized inhibitors are excellent and their (%η) was significantly increased by raising the dose and decreased by raising the temperature. Polarization curves revealed that the synthesized inhibitors act as mixed type. The thermodynamic parameters were calculated and discussed. The protection was confirmed by the creation of the thin film of inhibitors precipitated on the surface of CS.

Keywords: Supramolecular coordination polymers, acid corrosion, carbon steel, Henry isotherm, EIS.

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Sinteza dva supramolekularna koordinaciona polimera i elektrohemijska procena njihovog učinka inhibicije korozije na koroziju ugljeničnog čelika u kiseloj sredini

Izvod

Efekat SCPs-[Cu^II(en)₂] [Cu^I(CN)₂]₂. H₂O (SCP1) i {[H₂DAB] [Cu₄(CN)₆].2H₂O} (SCP2)  kao inhibitori korozije za ugljenični čelik (CS) proučavani su u 1,0 M rastvoru HCl. Kako se doza sintetizovanog inhibitora povećava, produktivnost inhibicije (%η) raste dostižući 90,3% i 89,9% pri dozi od 21×10^-6M za SCP2 i SCP1, respektivno. Ovaj rezultat je dokazan gubitkom mase (ML) ispitivanim na tri različitih temperatura 25-35-45⁰C, dok su potenciodinamička polarizacija (PP), spektroskopija elektrohemijske impedanse (EIS) i tehnika elektrohemijske modulacije frekvencije (EFM) testirani na 25°C. Sintetizovani inhibitori adsorbovani na površini CS fizički dozvoljavajući Henrijevu izotermu. Rezultati su pokazali da su sintetisani inhibitori odlični i da je njihov (%η) značajno povećan povećanjem doze i smanjen povećanjem temperature. Polarizacione krive su pokazale da sintetisani inhibitori deluju kao mešoviti tip. Termodinamički parametri su izračunati i diskutovani. Zaštita je potvrđena stvaranjem tankog filma inhibitora taloženog na površini CS.

Ključne reči: Supramolekularni koordinacioni polimeri, kisela korozija, ugljenični čelik, Henrijeva izoterma, EIS.

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A review of fungal influenced corrosion of metals

Abstract

The growth of fungi on the surface of metals has great influence on their structural integrity and failure. Their growth on metal surfaces is determined by their secreted metabolites which enable them to adapt to new environmental and nourishment conditions. Although information on the capacity of fungi to adapt to metal surfaces is scarce, most fungi growing on metal surfaces alter the composition of the metals involving it in the process of functional growth and metabolism. Changes in the composition and colour of the metals are some of the evidences confirming that fungus has penetrated the metal surfaces and use it to satisfy its nutritional need with resultant corrosion. In this work we tried to explain different mechanisms of fungal influenced corrosion from different perspectives ranging from the role of biofilms, corrosive media generation by fungal metabolism processes to electrochemical processes generated by fungal growth on metal surfaces. Finally, no single mechanism can conclusively explain all forms of fungal influenced corrosion because every mechanism is unique and applies to individual fungus, its metabolic bi-products or the growth pattern.

Keywords: Fungal corrosion, metals, corrosion mechanism, environment, corrosion.

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Pregled gljivične korozije metala

Izvod

Rast gljiva na površini metala ima veliki uticaj na njihov strukturni integritet i kvar. Njihov rast na metalnim površinama određen je izlučenim metabolitima koji im omogućavaju da se prilagode novim uslovima životne sredine i ishrane. Iako su informacije o sposobnosti gljiva da se prilagode metalnim površinama oskudne, većina gljiva koje rastu na metalnim površinama menjaju sastav metala koji ih uključuju u proces funkcionalnog rasta i metabolizma. Promene u sastavu metala i promene boje neki su od dokaza koji potvrđuju da je gljiva prodrla u metalne površine i koristi je za zadovoljavanje svojih nutritivnih potreba sa rezultujućom korozijom. U ovom radu pokušali smo objasniti različite mehanizme korozije pod uticajem gljivica iz različitih perspektiva, od uloge biofilmova, stvaranja korozivnih medija putem procesa metabolizma gljiva do elektrohemijskih procesa nastalih rastom gljivica na metalnim površinama. Konačno, nijedan jedinstven mehanizam ne može u potpunosti objasniti sve oblike korozije izazvane gljivicama, jer je svaki mehanizam jedinstven i primjenjuje se na pojedine gljive, njihove metaboličke nusproizvode ili obrazac rasta.

Ključne reči: gljivična korozija, metali, mehanizam korozije, životna sredina, korozija.

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Modified supersulfated cements

Abstract

The paper presents the results of experimental studies of the possibility of obtaining modified supersulfate cements (SSC) with improved physical and mechanical properties on lowalumina blast-furnace granular slags. It has been shown in comparative experimental tests of the effect of admixtures of various sulfate activators that the highest strength of cements is achieved when using a phosphogypsum neutralized with lime. An additional activating effect has been established for supersulfated cements with the introduction of admixtures fluorides and, in particular, fluorides of magnesium, calcium and sodium silicofluoride. The additional introduction of hardening accelerators and their compositions with a superplasticizer into the SSC composition makes it possible to increase the compressive strength of cements at 28 days of age up to 60-65 MPa while achieving high strength at an early age.

Along with standard tests, experiments were performed using mathematical planning with obtaining adequate regression equations.

Key words: blast furnace slag, sulfate activators, phosphogypsum, hardening accelerators, superplasticizer, lime, supersulfated cement, properties.

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Modifikovani supersulfatni cementi

Izvod

U radu su prikazani rezultati eksperimentalnih istraživanja mogućnosti dobijanja modifikovanih supersulfatnih cementa (SSC) sa poboljšanim fizičko-mehaničkim svojstvima na niskoaluminijskim zrnastim šljakama visoke peći. U uporednim eksperimentalnim ispitivanjima dejstva primesa različitih sulfatnih aktivatora pokazano je da se najveća čvrstoća cementa postiže upotrebom fosfogipsa neutralisanog krečom.

Dodatno aktivirajuće dejstvo je utvrđeno za supersulfatne cemente sa uvođenjem dodataka fluorida i posebno fluorida magnezijuma, kalcijuma i natrijum silikofluorida. Dodatno uvođenje akceleratora očvršćavanja i njihovih kompozicija sa superplastifikatorom u SSC sastav omogućava povećanje čvrstoće na pritisak cementa u starosti od 28 dana do 60-65 MPa uz postizanje visoke čvrstoće u ranom uzrastu.

Uporedo sa standardnim testovima, vršeni su eksperimenti primenom matematičkog planiranja uz dobijanje adekvatnih regresionih jednačina.

Ključne reči: šljaka visoke peći, sulfatni aktivatori, fosfogips, akceleratori očvršćavanja, superplastifikator, kreč, supersulfatni cement, svojstva.

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