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 sites

Transformation of the geopolymer gels to crystalline bonds in cold-setting refractory concretes: Pore evolution, mechanical strength and microstructure / Kamseu, Elie; Djangang, Chantale; Veronesi, Paolo; Andreola, Nora Maria; Melo, Uphie Chinje; Sglavo, Vincenzo Mario; Leonelli, Cristina. - In: MATERIALS & DESIGN. - ISSN 0264-1275. - ELETTRONICO. - 88:(2015), pp. 336-344. [10.1016/j.matdes.2015.08.151]

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

KAMSEU, Elie;VERONESI, Paolo;ANDREOLA, Nora Maria;LEONELLI, Cristina
2015

Abstract

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 sites
2015
88
336
344
Transformation of the geopolymer gels to crystalline bonds in cold-setting refractory concretes: Pore evolution, mechanical strength and microstructure / Kamseu, Elie; Djangang, Chantale; Veronesi, Paolo; Andreola, Nora Maria; Melo, Uphie Chinje; Sglavo, Vincenzo Mario; Leonelli, Cristina. - In: MATERIALS & DESIGN. - ISSN 0264-1275. - ELETTRONICO. - 88:(2015), pp. 336-344. [10.1016/j.matdes.2015.08.151]
Kamseu, Elie; Djangang, Chantale; Veronesi, Paolo; Andreola, Nora Maria; Melo, Uphie Chinje; Sglavo, Vincenzo Mario; Leonelli, Cristina
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/1076869
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