The thermal conductivity (Λ) of five specimens of aerated concrete varying in density from 390 to 900 kg/m3 has been measured at several moisture contents between 0.2 and 7 per cent volume. Although the Λ-value increased with increasing moisture content, the change was less than that predicted by the Jakob factors. In general, the moisture factors were found to be density dependent and to increase with decreasing conductivity. A general expression has been derived relating the moisture factor to both density and moisture content by volume over the range 0 to 5 per cent.
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References
1.
1 BS874: November 1973 and Amendment AMD 3006: August 1979, Methods for determining thermal insulating properties with definitions of thermal insulating terms.
2.
2 Jakob, M., Heat transfer, Part 1, London (Chapman and Hall, 1949).
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3 Chartered Institution of Building Services Engineers, CIBSE Guide A3, Thermal properties of building structures (1980).
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4 Arnold, Pamela J., Thermal conductivity of masonry materials, BRS Current Paper CP 1/70 (1970).
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5 Loudon, A. G., The effect of moisture content on thermal conductivity, Autoclaved Aerated Concrete, Moisture and Properties, Amsterdam, Elsevier Scientific Publishing, 131–141 (1983).
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6 Valore, R. C., Calculation of U-values of hollow concrete masonry, American Concrete Institute, 2/80, 40–63 (1980).
