The effect of moisture on the thermal conductivity of lightweight aggregate concrete

Abstract

The thermal conductivity (Λ) of 13 specimens of lightweight concrete, incorporating either Lytag, Pellite or Aglite aggregates, varying in density from 1144–1424 kg/m3 have been measured at several moisture contents between 0.03 and 19.75 per cent by volume. Although the Λ-value increased with increasing moisture content, the change was much 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 0–4 per cent. A comparison has been made between Λ obtained up to 6.5 per cent moisture content, corrected to 3 per cent using this expression, and experimental results at 3 per cent moisture content. Close agreement was obtained. This expression has also been used to correct the Λ-values to 5 per cent moisture content by volume and reasonable agreement has been obtained with the limited experimental data obtained at this level.