Abstract
Thermal conductivity (K) as functions of water content (w) is not so well known for swelling soils as that for non-swelling soils. We measured K and thermal diffusivity of a swelling soil taken from paddy fields in Indonesia, together with its shrinkage-swelling characteristic. The soil showed remarkable shrinkage-swelling nature ; void ratio of the soil in-situ exceeded 2.0 when flooded condition whereas it became less then 1.0 when the soil was dry. Observed K increased from 0.60 to 1.28 W m-1 K-1 with w increased from zero to 0.24 gg-1. However, for w greater than
0.24 gg-1, K decreased gradually with increase in w, differently from non-swelling soil that shows monotonic increase with w. The decrease in K with increase in w must be produced by increased void ratio. As a result, the value of K for the soil of most dry condition in the field (K = 0.99 W m-1K-1) was almost the same as the value of K for flooded condition. Consequently, drying of the swelling soil has no effects of reducing heat conduction from surface into the soil when it is exposed to sunshine.
