Colemanite is a natural borate that can be used as an aggregate in neutron-radiation shielding concretes. In this study, we report its thermal behavior, up to 500 °C, by describing: 1) its dehydration mechanisms and 2) its thermo-elastic parameters. The thermal expansion of colemanite is significantly anisotropic. The refined volume thermal expansion coefficient at ambient conditions is: αV0 = 4.50(10)·10−5 K−1. The loss of structural H2O occurs at least from ∼240 °C, and at T > 325 °C an irreversible amorphization occurs, followed by a complete dehydration. The potential implications on the use of colemanite as concrete-aggregate are discussed.

Thermal stability and high-temperature behavior of the natural borate colemanite: An aggregate in radiation-shielding concretes / P. Lotti, D. Comboni, L. Gigli, L. Carlucci, E. Mossini, E. Macerata, M. Mariani, G.D. Gatta. - In: CONSTRUCTION AND BUILDING MATERIALS. - ISSN 0950-0618. - 203(2019 Apr 10), pp. 679-686. [10.1016/j.conbuildmat.2019.01.123]

Thermal stability and high-temperature behavior of the natural borate colemanite: An aggregate in radiation-shielding concretes

P. Lotti
Primo
;
D. Comboni
Secondo
;
L. Carlucci;G.D. Gatta
Ultimo
2019-04-10

Abstract

Colemanite is a natural borate that can be used as an aggregate in neutron-radiation shielding concretes. In this study, we report its thermal behavior, up to 500 °C, by describing: 1) its dehydration mechanisms and 2) its thermo-elastic parameters. The thermal expansion of colemanite is significantly anisotropic. The refined volume thermal expansion coefficient at ambient conditions is: αV0 = 4.50(10)·10−5 K−1. The loss of structural H2O occurs at least from ∼240 °C, and at T > 325 °C an irreversible amorphization occurs, followed by a complete dehydration. The potential implications on the use of colemanite as concrete-aggregate are discussed.
Amorphization; Boron; Colemanite; Dehydration; High temperature; Neutron radiation shielding concretes; Synchrotron X-ray diffraction; Thermal expansion coefficient; Civil and Structural Engineering; Building and Construction; Materials Science (all)
Settore GEO/09 - Georisorse Miner.Appl.Mineral.-Petrogr.per l'amb.e i Beni Cul
Settore CHIM/03 - Chimica Generale e Inorganica
Settore ING-IND/20 - Misure e Strumentazione Nucleari
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/621869
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