TY  - JOUR
AU  - Baščarević, Zvezdana
AU  - Komljenović, Miroslav
AU  - Miladinović, Zoran P.
AU  - Nikolić, Violeta
AU  - Marjanović, Nataša
AU  - Petrović, Rada
PY  - 2015
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3039
AB  - In this paper, geopolymers based on two different fly ash samples were exposed to sodium sulfate (Na2SO4) solution (50 g/l) over a period of 365 days. It was found that sulfate solution attack caused a small decrease in strength of geopolymer mortars. Analysis of the Na2SO4 solutions by optical emission spectroscopy indicated that exposing of the geopolymer samples to the Na2SO4 solution had caused leaching of one of the elements of the aluminosilicate gel, silicon. Mineralogical analyses of geopolymer samples did not show formation of any new phases due to a reaction with sulfate ions. Changes in aluminosilicate geopolymer gel due to sulfate attack were investigated by electron microscopy and nuclear magnetic resonance. It was found that treatment of geopolymer samples with the sulfate solution caused breaking of -Si-O-Si- bonds in aluminosilicate gel structure. Breaking of the -Si-O-Si- bonds and leaching of Si were consequences of the increase in the pH value of sulfate solution during testing.
PB  - Springer, Dordrecht
T2  - Materials and Structures
T1  - Impact of sodium sulfate solution on mechanical properties and structure of fly ash based geopolymers
EP  - 697
IS  - 3
SP  - 683
VL  - 48
DO  - 10.1617/s11527-014-0325-4
ER  - 

@article{
author = "Baščarević, Zvezdana and Komljenović, Miroslav and Miladinović, Zoran P. and Nikolić, Violeta and Marjanović, Nataša and Petrović, Rada",
year = "2015",
abstract = "In this paper, geopolymers based on two different fly ash samples were exposed to sodium sulfate (Na2SO4) solution (50 g/l) over a period of 365 days. It was found that sulfate solution attack caused a small decrease in strength of geopolymer mortars. Analysis of the Na2SO4 solutions by optical emission spectroscopy indicated that exposing of the geopolymer samples to the Na2SO4 solution had caused leaching of one of the elements of the aluminosilicate gel, silicon. Mineralogical analyses of geopolymer samples did not show formation of any new phases due to a reaction with sulfate ions. Changes in aluminosilicate geopolymer gel due to sulfate attack were investigated by electron microscopy and nuclear magnetic resonance. It was found that treatment of geopolymer samples with the sulfate solution caused breaking of -Si-O-Si- bonds in aluminosilicate gel structure. Breaking of the -Si-O-Si- bonds and leaching of Si were consequences of the increase in the pH value of sulfate solution during testing.",
publisher = "Springer, Dordrecht",
journal = "Materials and Structures",
title = "Impact of sodium sulfate solution on mechanical properties and structure of fly ash based geopolymers",
pages = "697-683",
number = "3",
volume = "48",
doi = "10.1617/s11527-014-0325-4"
}

Baščarević, Z., Komljenović, M., Miladinović, Z. P., Nikolić, V., Marjanović, N.,& Petrović, R.. (2015). Impact of sodium sulfate solution on mechanical properties and structure of fly ash based geopolymers. in Materials and Structures
Springer, Dordrecht., 48(3), 683-697.
https://doi.org/10.1617/s11527-014-0325-4

Baščarević Z, Komljenović M, Miladinović ZP, Nikolić V, Marjanović N, Petrović R. Impact of sodium sulfate solution on mechanical properties and structure of fly ash based geopolymers. in Materials and Structures. 2015;48(3):683-697.
doi:10.1617/s11527-014-0325-4 .

Baščarević, Zvezdana, Komljenović, Miroslav, Miladinović, Zoran P., Nikolić, Violeta, Marjanović, Nataša, Petrović, Rada, "Impact of sodium sulfate solution on mechanical properties and structure of fly ash based geopolymers" in Materials and Structures, 48, no. 3 (2015):683-697,
https://doi.org/10.1617/s11527-014-0325-4 . .

TY  - JOUR
AU  - Marjanović, Nataša
AU  - Komljenović, Miroslav
AU  - Baščarević, Zvezdana
AU  - Nikolić, V.
AU  - Petrović, Rada
PY  - 2015
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3020
AB  - This paper investigated physical mechanical and microstructural properties of alkali-activated binders based on blends of fly ash (FA) and blast furnace slag (BFS). FA BFS blends were alkali-activated with sodium silicate (water glass) solution. The synthesis of alkali-activated binders was conducted at 95 C during 24 h, with different FA BFS mass ratios (100:0; 75:25; 50:50; 25:75; 0:100), different moduli of alkali activator (SiO2/Na2O: 0.5; 1.0; 1.5) and different alkali activator concentration (% Na2O: 4; 7; 10). The influence of alkali activation conditions on the flexural and compressive strengths, setting time, drying shrinkage and the microstructure of synthesized binders was investigated. It was found that the compressive strength mostly depended on the composition of the FA BFS blends and the water/binder ratio. The setting time highly depended on the activator concentration, while the drying shrinkage was mostly affected by the curing temperature. The blend comprising FA 25% BFS 75%, activated with the activator of modulus 1.0 and the activator concentration of 10% Na2O yielded optimal mortar regarding investigated physical mechanical characteristics. Microstuctural examination showed that the chemical composition of the binding phase varied as a function of the blend composition. Predominance of FA alkali reaction products in the binding phase positively influenced the flexural strength, while the predominance of BFS alkali reaction products positively affected the compressive strength. Optimal characteristics of alkaliactivated binder were related to the following chemical composition of the binding gel: Ca/Si= 0.34-0.50, Al/Si=0.15-0.24, Mg/Si= 0.07-0.16 and Na/Si=0.21-0.37. Empirical values of optimal gel composition could serve as a basis for tailoring the properties of alkali-activated binders based on different industrial waste precursor material.
PB  - Elsevier Sci Ltd, Oxford
T2  - Ceramics International
T1  - Physical-mechanical and microstructural properties of alkali-activated fly ash-blast furnace slag blends
EP  - 1435
IS  - 1
SP  - 1421
VL  - 41
DO  - 10.1016/j.ceramint.2014.09.075
ER  - 

@article{
author = "Marjanović, Nataša and Komljenović, Miroslav and Baščarević, Zvezdana and Nikolić, V. and Petrović, Rada",
year = "2015",
abstract = "This paper investigated physical mechanical and microstructural properties of alkali-activated binders based on blends of fly ash (FA) and blast furnace slag (BFS). FA BFS blends were alkali-activated with sodium silicate (water glass) solution. The synthesis of alkali-activated binders was conducted at 95 C during 24 h, with different FA BFS mass ratios (100:0; 75:25; 50:50; 25:75; 0:100), different moduli of alkali activator (SiO2/Na2O: 0.5; 1.0; 1.5) and different alkali activator concentration (% Na2O: 4; 7; 10). The influence of alkali activation conditions on the flexural and compressive strengths, setting time, drying shrinkage and the microstructure of synthesized binders was investigated. It was found that the compressive strength mostly depended on the composition of the FA BFS blends and the water/binder ratio. The setting time highly depended on the activator concentration, while the drying shrinkage was mostly affected by the curing temperature. The blend comprising FA 25% BFS 75%, activated with the activator of modulus 1.0 and the activator concentration of 10% Na2O yielded optimal mortar regarding investigated physical mechanical characteristics. Microstuctural examination showed that the chemical composition of the binding phase varied as a function of the blend composition. Predominance of FA alkali reaction products in the binding phase positively influenced the flexural strength, while the predominance of BFS alkali reaction products positively affected the compressive strength. Optimal characteristics of alkaliactivated binder were related to the following chemical composition of the binding gel: Ca/Si= 0.34-0.50, Al/Si=0.15-0.24, Mg/Si= 0.07-0.16 and Na/Si=0.21-0.37. Empirical values of optimal gel composition could serve as a basis for tailoring the properties of alkali-activated binders based on different industrial waste precursor material.",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Ceramics International",
title = "Physical-mechanical and microstructural properties of alkali-activated fly ash-blast furnace slag blends",
pages = "1435-1421",
number = "1",
volume = "41",
doi = "10.1016/j.ceramint.2014.09.075"
}

Marjanović, N., Komljenović, M., Baščarević, Z., Nikolić, V.,& Petrović, R.. (2015). Physical-mechanical and microstructural properties of alkali-activated fly ash-blast furnace slag blends. in Ceramics International
Elsevier Sci Ltd, Oxford., 41(1), 1421-1435.
https://doi.org/10.1016/j.ceramint.2014.09.075

Marjanović N, Komljenović M, Baščarević Z, Nikolić V, Petrović R. Physical-mechanical and microstructural properties of alkali-activated fly ash-blast furnace slag blends. in Ceramics International. 2015;41(1):1421-1435.
doi:10.1016/j.ceramint.2014.09.075 .

Marjanović, Nataša, Komljenović, Miroslav, Baščarević, Zvezdana, Nikolić, V., Petrović, Rada, "Physical-mechanical and microstructural properties of alkali-activated fly ash-blast furnace slag blends" in Ceramics International, 41, no. 1 (2015):1421-1435,
https://doi.org/10.1016/j.ceramint.2014.09.075 . .

TY  - JOUR
AU  - Nikolić, Violeta
AU  - Komljenović, Miroslav
AU  - Baščarević, Zvezdana
AU  - Marjanović, Nataša
AU  - Miladinović, Zoran P.
AU  - Petrović, Rada
PY  - 2015
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/2963
AB  - Reactivity of Class F fly ash (FA), development of strength, and structure of FA-based geopolymers, depending on the reaction conditions, were examined in this paper. The results of SEM/EDS and NMR analyses revealed that the composition of aluminosilicate gel changed during reaction, i.e. Si/Al atomic ratio decreased with the reaction time. Higher strength of geopolymers was associated with a higher fraction of aluminum rich structural units, higher crosslinking, and more compact structure. A rapid test for the assessment of FA reactivity and thus the applicability of FA for geopolymer synthesis was proposed.
PB  - Elsevier Sci Ltd, Oxford
T2  - Construction and Building Materials
T1  - The influence of fly ash characteristics and reaction conditions on strength and structure of geopolymers
EP  - 370
SP  - 361
VL  - 94
DO  - 10.1016/j.conbuildmat.2015.07.014
ER  - 

@article{
author = "Nikolić, Violeta and Komljenović, Miroslav and Baščarević, Zvezdana and Marjanović, Nataša and Miladinović, Zoran P. and Petrović, Rada",
year = "2015",
abstract = "Reactivity of Class F fly ash (FA), development of strength, and structure of FA-based geopolymers, depending on the reaction conditions, were examined in this paper. The results of SEM/EDS and NMR analyses revealed that the composition of aluminosilicate gel changed during reaction, i.e. Si/Al atomic ratio decreased with the reaction time. Higher strength of geopolymers was associated with a higher fraction of aluminum rich structural units, higher crosslinking, and more compact structure. A rapid test for the assessment of FA reactivity and thus the applicability of FA for geopolymer synthesis was proposed.",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Construction and Building Materials",
title = "The influence of fly ash characteristics and reaction conditions on strength and structure of geopolymers",
pages = "370-361",
volume = "94",
doi = "10.1016/j.conbuildmat.2015.07.014"
}

Nikolić, V., Komljenović, M., Baščarević, Z., Marjanović, N., Miladinović, Z. P.,& Petrović, R.. (2015). The influence of fly ash characteristics and reaction conditions on strength and structure of geopolymers. in Construction and Building Materials
Elsevier Sci Ltd, Oxford., 94, 361-370.
https://doi.org/10.1016/j.conbuildmat.2015.07.014

Nikolić V, Komljenović M, Baščarević Z, Marjanović N, Miladinović ZP, Petrović R. The influence of fly ash characteristics and reaction conditions on strength and structure of geopolymers. in Construction and Building Materials. 2015;94:361-370.
doi:10.1016/j.conbuildmat.2015.07.014 .

Nikolić, Violeta, Komljenović, Miroslav, Baščarević, Zvezdana, Marjanović, Nataša, Miladinović, Zoran P., Petrović, Rada, "The influence of fly ash characteristics and reaction conditions on strength and structure of geopolymers" in Construction and Building Materials, 94 (2015):361-370,
https://doi.org/10.1016/j.conbuildmat.2015.07.014 . .

TY  - JOUR
AU  - Nikolić, Violeta
AU  - Komljenović, Miroslav
AU  - Marjanović, Nataša
AU  - Baščarević, Zvezdana
AU  - Petrović, Rada
PY  - 2014
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/2785
AB  - In this paper, the effectiveness of geopolymers based on initial and mechanically activated fly ash in immobilization of lead was investigated. Fly ash (FA) was firstly mechanically and then alkali activated at room temperature. The immobilization process was assessed by the means of the mechanical and leaching properties of geopolymers. The results indicated that the geopolymers based on mechanically activated FA were more effective in the immobilization of lead compared to the geopolymers based on the initial FA. Mechanical activation of FA led to a significant increase in strength and reduced Pb leaching from geopolymers. Higher effectiveness of Pb immobilization was the result of reduced porosity, i.e. higher compactness of geopolymers based on mechanically activated FA.
PB  - Elsevier Sci Ltd, Oxford
T2  - Ceramics International
T1  - Lead immobilization by geopolymers based on mechanically activated fly ash
EP  - 8488
IS  - 6
SP  - 8479
VL  - 40
DO  - 10.1016/j.ceramint.2014.01.059
ER  - 

@article{
author = "Nikolić, Violeta and Komljenović, Miroslav and Marjanović, Nataša and Baščarević, Zvezdana and Petrović, Rada",
year = "2014",
abstract = "In this paper, the effectiveness of geopolymers based on initial and mechanically activated fly ash in immobilization of lead was investigated. Fly ash (FA) was firstly mechanically and then alkali activated at room temperature. The immobilization process was assessed by the means of the mechanical and leaching properties of geopolymers. The results indicated that the geopolymers based on mechanically activated FA were more effective in the immobilization of lead compared to the geopolymers based on the initial FA. Mechanical activation of FA led to a significant increase in strength and reduced Pb leaching from geopolymers. Higher effectiveness of Pb immobilization was the result of reduced porosity, i.e. higher compactness of geopolymers based on mechanically activated FA.",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Ceramics International",
title = "Lead immobilization by geopolymers based on mechanically activated fly ash",
pages = "8488-8479",
number = "6",
volume = "40",
doi = "10.1016/j.ceramint.2014.01.059"
}

Nikolić, V., Komljenović, M., Marjanović, N., Baščarević, Z.,& Petrović, R.. (2014). Lead immobilization by geopolymers based on mechanically activated fly ash. in Ceramics International
Elsevier Sci Ltd, Oxford., 40(6), 8479-8488.
https://doi.org/10.1016/j.ceramint.2014.01.059

Nikolić V, Komljenović M, Marjanović N, Baščarević Z, Petrović R. Lead immobilization by geopolymers based on mechanically activated fly ash. in Ceramics International. 2014;40(6):8479-8488.
doi:10.1016/j.ceramint.2014.01.059 .

Nikolić, Violeta, Komljenović, Miroslav, Marjanović, Nataša, Baščarević, Zvezdana, Petrović, Rada, "Lead immobilization by geopolymers based on mechanically activated fly ash" in Ceramics International, 40, no. 6 (2014):8479-8488,
https://doi.org/10.1016/j.ceramint.2014.01.059 . .

TY  - JOUR
AU  - Miladinović, Zoran P.
AU  - Zakrzewska, Joanna
AU  - Kovacević, Branimir T.
AU  - Miladinović, Jelena
PY  - 2014
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/2812
AB  - In this study, in situ Al-27 NMR spectroscopy was used to gain detailed information concerning kinetics of zeolite A crystallization. Changes of relative intensity and width at half-height of NMR lines at 59 ppm ascribed to Al(OSi)(4) solid structures units and at 79 ppm to Al(OH) T ions in liquid phase during crystallization, were observed. Normalized curves for series of synthesis, performed under different batch molar composition, were used for kinetic analysis applying Sharp and Hancock approach. The influence of total batch Na2O concentration (H2O/Na20 was 20 and 32) for three specific batch SiO2/Al2O3 molar ratios (1.7, 2.0 and 2.5) on the kinetic parameters was investigated. Kinetic analysis of line at 79 ppm provided values of parameter n that ranged from 0.93 to 1.97 indicating contribution of both diffusion and phase boundary controlled mechanisms, depending on batch SiO2/Al2O3 molar composition. On the other hand, analysis of line at 59 ppm showed strong correlation to Na2O batch content. Values of n from 1.94 to 3.34 for syntheses performed at lower alkalinity conditions (H2O/Na2O = 32) indicate Avrami-Erofe'ev nucleation and crystal growth model. Almost dominant presence of diffusion mechanism for synthesis conducted at higher alkalinity conditions (H2O/Na2O = 20) was verified by obtained values of n gathered around 1.5.
PB  - Elsevier Science Bv, Amsterdam
T2  - Microporous and Mesoporous Materials
T1  - In situ Al-27 NMR kinetic investigation of zeolite A crystallization
EP  - 142
SP  - 131
VL  - 195
DO  - 10.1016/j.micromeso.2014.04.022
ER  - 

@article{
author = "Miladinović, Zoran P. and Zakrzewska, Joanna and Kovacević, Branimir T. and Miladinović, Jelena",
year = "2014",
abstract = "In this study, in situ Al-27 NMR spectroscopy was used to gain detailed information concerning kinetics of zeolite A crystallization. Changes of relative intensity and width at half-height of NMR lines at 59 ppm ascribed to Al(OSi)(4) solid structures units and at 79 ppm to Al(OH) T ions in liquid phase during crystallization, were observed. Normalized curves for series of synthesis, performed under different batch molar composition, were used for kinetic analysis applying Sharp and Hancock approach. The influence of total batch Na2O concentration (H2O/Na20 was 20 and 32) for three specific batch SiO2/Al2O3 molar ratios (1.7, 2.0 and 2.5) on the kinetic parameters was investigated. Kinetic analysis of line at 79 ppm provided values of parameter n that ranged from 0.93 to 1.97 indicating contribution of both diffusion and phase boundary controlled mechanisms, depending on batch SiO2/Al2O3 molar composition. On the other hand, analysis of line at 59 ppm showed strong correlation to Na2O batch content. Values of n from 1.94 to 3.34 for syntheses performed at lower alkalinity conditions (H2O/Na2O = 32) indicate Avrami-Erofe'ev nucleation and crystal growth model. Almost dominant presence of diffusion mechanism for synthesis conducted at higher alkalinity conditions (H2O/Na2O = 20) was verified by obtained values of n gathered around 1.5.",
publisher = "Elsevier Science Bv, Amsterdam",
journal = "Microporous and Mesoporous Materials",
title = "In situ Al-27 NMR kinetic investigation of zeolite A crystallization",
pages = "142-131",
volume = "195",
doi = "10.1016/j.micromeso.2014.04.022"
}

Miladinović, Z. P., Zakrzewska, J., Kovacević, B. T.,& Miladinović, J.. (2014). In situ Al-27 NMR kinetic investigation of zeolite A crystallization. in Microporous and Mesoporous Materials
Elsevier Science Bv, Amsterdam., 195, 131-142.
https://doi.org/10.1016/j.micromeso.2014.04.022

Miladinović ZP, Zakrzewska J, Kovacević BT, Miladinović J. In situ Al-27 NMR kinetic investigation of zeolite A crystallization. in Microporous and Mesoporous Materials. 2014;195:131-142.
doi:10.1016/j.micromeso.2014.04.022 .

Miladinović, Zoran P., Zakrzewska, Joanna, Kovacević, Branimir T., Miladinović, Jelena, "In situ Al-27 NMR kinetic investigation of zeolite A crystallization" in Microporous and Mesoporous Materials, 195 (2014):131-142,
https://doi.org/10.1016/j.micromeso.2014.04.022 . .

TY  - JOUR
AU  - Baščarević, Zvezdana
AU  - Komljenović, Miroslav
AU  - Miladinović, Zoran P.
AU  - Nikolić, Violeta
AU  - Marjanović, Nataša
AU  - Zujović, Zoran
AU  - Petrović, Rada
PY  - 2013
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/2521
AB  - The geopolymers based on fly ash were exposed to the concentrated (6 M) NH4NO3 solution for 540 days. The highest compressive strength decrease occurred in the initial 28 days testing period. Study of the effects of the NH4NO3 solution on the geopolymer structure indicated leaching of alkali and alkaline earth cations and breaking of -Si-O-Al- bonds in aluminosilicate gel. The reduction of compressive strength of the geopolymers was associated with the structural defects in the aluminosilicate gel created by breaking of -Si-O-Al- bonds. Subsequent fluctuation in compressive strength was a result of the structural defects reparation by silicon.
PB  - Elsevier Sci Ltd, Oxford
T2  - Construction and Building Materials
T1  - Effects of the concentrated NH4NO3 solution on mechanical properties and structure of the fly ash based geopolymers
EP  - 579
SP  - 570
VL  - 41
DO  - 10.1016/j.conbuildmat.2012.12.067
ER  - 

@article{
author = "Baščarević, Zvezdana and Komljenović, Miroslav and Miladinović, Zoran P. and Nikolić, Violeta and Marjanović, Nataša and Zujović, Zoran and Petrović, Rada",
year = "2013",
abstract = "The geopolymers based on fly ash were exposed to the concentrated (6 M) NH4NO3 solution for 540 days. The highest compressive strength decrease occurred in the initial 28 days testing period. Study of the effects of the NH4NO3 solution on the geopolymer structure indicated leaching of alkali and alkaline earth cations and breaking of -Si-O-Al- bonds in aluminosilicate gel. The reduction of compressive strength of the geopolymers was associated with the structural defects in the aluminosilicate gel created by breaking of -Si-O-Al- bonds. Subsequent fluctuation in compressive strength was a result of the structural defects reparation by silicon.",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Construction and Building Materials",
title = "Effects of the concentrated NH4NO3 solution on mechanical properties and structure of the fly ash based geopolymers",
pages = "579-570",
volume = "41",
doi = "10.1016/j.conbuildmat.2012.12.067"
}

Baščarević, Z., Komljenović, M., Miladinović, Z. P., Nikolić, V., Marjanović, N., Zujović, Z.,& Petrović, R.. (2013). Effects of the concentrated NH4NO3 solution on mechanical properties and structure of the fly ash based geopolymers. in Construction and Building Materials
Elsevier Sci Ltd, Oxford., 41, 570-579.
https://doi.org/10.1016/j.conbuildmat.2012.12.067

Baščarević Z, Komljenović M, Miladinović ZP, Nikolić V, Marjanović N, Zujović Z, Petrović R. Effects of the concentrated NH4NO3 solution on mechanical properties and structure of the fly ash based geopolymers. in Construction and Building Materials. 2013;41:570-579.
doi:10.1016/j.conbuildmat.2012.12.067 .

Baščarević, Zvezdana, Komljenović, Miroslav, Miladinović, Zoran P., Nikolić, Violeta, Marjanović, Nataša, Zujović, Zoran, Petrović, Rada, "Effects of the concentrated NH4NO3 solution on mechanical properties and structure of the fly ash based geopolymers" in Construction and Building Materials, 41 (2013):570-579,
https://doi.org/10.1016/j.conbuildmat.2012.12.067 . .