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Structure, Microstructure and Properties of Lightweight Aluminosilicate Refractory Aggregates and Castables
D. Madej, A. Bąk, D. Bielewicz, A. Aksamit, A. Hecman, W. Mikulski
Abstract
Lightweight aggregates and castables are of great significance for energy saving and the reduction of emissions. In this work, lightweight aluminosilicate aggregates were produced using high-quality kaolin and porogenous material by means of high-temperature processing and investigated in terms of XRD mineralogy, bulk density, open porosity, and microstructure. In addition, the influence of the lightweight aggregates on the bulk density, cold crushing strength, microstructure, thermal properties and thermal shock resistance of refractory castables was investigated in detail. For this reason, lightweight castables with different particle size distribution, as per the Dinger and Funk model, were designed to attain very good flow consistency, cast, cured and heat-treated at temperatures between 110 – 1 200 °C. The lightweight castables with chamotte aggregates presented improved performance, exhibiting bulk density of 1.64 g/cm3 to 1.77 g/cm3, cold crushing strength of 30.3 MPa to 54.8 MPa and thermal conductivity of 0.66 to 0.74 W/m·K measured at room temperature, depending on the firing temperature (850 °C – 1 200 °C) and lightweight aggregates content. The results underscore that the use of microporous aggregates instead of traditional dense aggregates enabled the design of semi-insulating castables for the working lining of kilns and furnaces with improved properties, eliminating the need for porogenic agents.
Keywords
Lightweight aggregate, lightweight castable, monolithic refractories, energy savings, reduced heat loss, university-business cooperation.
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