Preparation, characterisation and industrial evaluation of foamed fireclay


In this study, the direct foaming method was used to prepare groups of porous fireclay refractories containing 36–42 wt% Al2O3 from Aswan ball clay and Kalabsha kaolin (local raw material). A mixture of calcium oxide or carbide and aluminium powder was used as a foaming agent. Sodium silicate and a surfactant were employed to assist the foaming process. The physico-mechanical and mineralogical properties in addition to the microstructure characteristics of the fired samples were investigated using standard methods in addition to the XRD and SEM techniques. The effects of some preparation variables such as foaming agent, firing temperature and clay type on their properties and microstructure were also studied. The results indicated that, when CaC2 was used instead of CaO as a foaming agent, an enlargement in pore sizes accompanied with a decrease in the bulk density of samples takes place, particularly when the water content increases. On increasing the firing temperature from 1350 to 1450 °C, the pore sizes of the samples decrease, and hence, their bulk density increases. The replacement of ≥ 25 wt% of Aswan ball clay with Kalabsha kaolin improves its chemical composition and physical properties to be more suitable for the foaming process. The prepared samples are classified based on their bulk density and application temperature in groups 24–26 and class L according to ASTM and UN specifications.

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Hanna, S.B., Ajiba, N.A. Preparation, characterisation and industrial evaluation of foamed fireclay. J Aust Ceram Soc 56, 663–681 (2020).

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  • Porous aluminosilicate
  • Direct foaming method
  • Kalabsha kaolin
  • Aswan ball clay