Effect of cure temperature on the formation of metakaolinite-based geopolymer

Aredes, F.G.M.; Campos, Tiago Moreira Bastos; Machado, João Paulo Barros; Sakane, Kumiko Koibuchi; Thim, Gilmar Patrocínio; Brunelli, Deborah Dibbern

doi:10.1016/j.ceramint.2015.02.022

Cited by 132 publications

(46 citation statements)

References 28 publications

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“…Portland cement (CEM O 42.5) having relative density 3100 kg/m 3 (relative density is the ratio of the mass of a unit volume of cement to the density of a given reference [5]. For each mix, six specimens were used and the average of these three values was reported b The flexural strength test was performed on dried specimens in accordance with ASTM C348-08 [6] c In fresh pastes, the initial and final setting time was determined using the Vicat apparatus in accordance with the ASTM C191 [7] standard test method material, usually with respect to water), specific surface area 369.6 m 2 /kg (specific surface area is a property of cement which is the total surface area per unit of mass), chemical composition as shown in Table 1 and strength and setting properties as shown in Table 2 was used.…”

Section: Methodsmentioning

confidence: 99%

“…Based on the properties mentioned above, researchers are showing wide interest in geopolymer binders, i.e., the alkali activated binders with metakaolin or fly ash precursors. However, the literature on portland cement and geopolymer exposed to high temperature at about 1000 • C is scant [1][2][3][4][5][6][7]. Therefore, this paper provides a comparison of high-temperatureexposed pastes of OPC and geopolymer comprised of fly ash, metakaolin and sodium silicate (Na 2 SiO 3 ) and sodium hydroxide (NaOH) solutions.…”

Section: Introductionmentioning

confidence: 98%

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Thermal Behavior of Portland Cement and Fly Ash–Metakaolin-Based Geopolymer Cement Pastes

et al. 2015

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Geopolymer specimens were prepared by combination of fly ash and metakaolin activated by sodium silicate (Na 2 SiO 3 ) and sodium hydroxide (NaOH) solutions. The effect of high temperature on the compressive strength, mass loss and shrinkage of geopolymer cement pastes and ordinary portland cement (OPC) pastes were assessed experimentally. Microstructure formation and development were characterized in terms of pore structure by mercury intrusion porosimetry. The results reveal that at temperatures exceeding 400 • C geopolymer cement paste is superior to OPC paste. Firstly, the compressive strength drops rapidly for the OPC paste to practically zero strength at 600 • C, while it drops slowly for the fly ash-metakaolin-based geopolymer cement paste to 46 MPa at 1000 • C. Secondly, while the mass loss increases for the OPC paste, it is maintained at a constant, lower value for the geopolymer cement paste. Thirdly, shrinkage of geopolymer cement paste is at least three times smaller than that of OPC paste.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Thermal Behavior of Portland Cement and Fly Ash–Metakaolin-Based Geopolymer Cement Pastes

et al. 2015

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“…At low temperature metastable μ-cordierite is possible to be formed as well as β-cordierite. At high temperature, hexagonal form is developed [23,24]. The kyanite aggregates act to improve the phase separation playing the role of nucleation sites and enhance crystallization.…”

Section: Correlation Of the Sintering Behavior And Phases Evolution Wmentioning

confidence: 99%

Transformation of the geopolymer gels to crystalline bonds in cold-setting refractory concretes: Pore evolution, mechanical strength and microstructure

et al. 2015

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Two K2O-MgO-Al2O3-SiO2 based geopolymer gels with bulk chemical composition corresponding to cordierite (Co) and 1:1 mullite-cordierite (MuCo) were successfully transformed to crystalline bonds in high temperature service of cold-setting made refractory concretes. Kyanite aggregates changed the flexural strength of the gels from11 to 28 MPa due to the development of good adhesive bonds. Under thermal cycles, up to 1250 °C, the cumulative pore volume remained at 0.09 mL/g, as fromthe absence of important densification/shrinkage. However, the behavior of the cumulative pore volume curves changed from that of a matrix with a wide range of distribution of pore sizes to that, of matrix, consisting of relatively coarse grains. The latter exhibits a rise at 10 μm as void spaces created around the contact points among the coarse kyanite grains and that at 0.054 μm as poreswithin the crystalline phases (cordierite, kalsilite, leucite,mullite, enstatite) formed. Themicrostructural observations confirmed the transformation of gel pores (size around 0.01 μm) to interparticle and intergranular pores due to the crystallization. The flexural strength of refractory concretes increased from28MPa to 40MPa in agreement with the increase in the elastic modulus from 9 to 30 GPa. The crystallization was enhanced by the MgO content (being important in Co compared to MuCo) and the kyanite concentration as particles of kyanite effectively acted as phase separation and nucleation site

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“…This sludge contains a substantial amount of silica and alumina as crystalline kaolinite, which can be used to produce geopolymer cement. Physicochemical and mechanical properties of geopolymer cement depend on the nature of Aluminosilicate source (mineralogical composition, degree of crystallinity) [13][14][15][16][17], calcination method and temperature [18][19][20], nature of alkali metal cations [21,22], Si/Al molar ratio [23,24], Na 2 SiO 3 /NaOH mass ratio [25,26], Na 2 O/Al 2 O 3 molar ratios [27], temperature and curing time [28][29][30]. This research introduces a comparative study between two geopolymers, synthesized from two different raw materials: The industrial sludge and Metakaolin.…”

Section: Introductionmentioning

confidence: 99%

Comparison of the microstructure and the compressive strength of two geopolymers derived from Metakaolin and an industrial sludge

Belmokhtar

Ammari

Brigui

et al. 2017

Construction and Building Materials

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Effect of cure temperature on the formation of metakaolinite-based geopolymer

Cited by 132 publications

References 28 publications

Thermal Behavior of Portland Cement and Fly Ash–Metakaolin-Based Geopolymer Cement Pastes

Thermal Behavior of Portland Cement and Fly Ash–Metakaolin-Based Geopolymer Cement Pastes

Transformation of the geopolymer gels to crystalline bonds in cold-setting refractory concretes: Pore evolution, mechanical strength and microstructure

Comparison of the microstructure and the compressive strength of two geopolymers derived from Metakaolin and an industrial sludge

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