Heimberg, Matthias

Seiferlin, Karsten

Thomas, Nicolas

Bern Open Repository and Information System (BORIS)

Geophysical Research Abstracts, Vol. 9, 02361, 2007SRef-ID: 1607-7962/gra/EGU2007-A-02361© European Geosciences Union 2007The Effect of Soil Cementation on the ThermalConductivityK. Seiferlin (1), M. Heimberg (1), N. Thomas (1)Physikalisches Institut, Universität BernThe study presented here aims at a better understanding of consolidated porous media,such as sintered ice, which may be present in near surface layers of comet nuclei, andin the Martian polar deposits, or cemented Martian soil. Martian soil, for instance, maybe consolidated either by interstitial water or carbon dioxide ice, or by clay mineralsand salts. In either case the consolidation is a direct consequence of an increased grain-to-grain contact area. The cross section of these bonds are bottle necks for solid stateheat conduction, which therefore improves with the growth of bonds.We performed thermal conductivity measurements performed in vacuum on loose andconsolidated synthetic samples. Small glass beads served as an analogue of soil grainsand initially melted wax as the cementing agent, which creates, after mixing with theglass beads and subsequent solidification, a surprisingly hard but still porous material.Several samples with ranging from 0 to 11 % wax content have been produced andstudied. A commercial probe, which employs a modified transient line heat sourcetechnique was used to measure the thermal conductivity. We found the thermal con-ductivity to grow with cementation, as expected. The sample with the highest degreeof cementation conducts heat three times better than the unconsolidated, pure glasssample. A simple geometrical model, describing the size of the bonds as a function ofwax content, is capable to predict the observed values reasonably well. The observedeffect is significant, but not large enough to explain the wide range of thermal inertiavalues that have been measured by the TES instrument on Mars Global Surveyor. Thisresult confirms that the thermal inertia variation of the Martian surface is at least partlydue to rock abundance.

The Effect of Soil Cementation on the Thermal Conductivity

http://www.cosis.net/abstracts/EGU2007/02361/EGU2007-J-02361.pdf

The Effect of Soil Cementation on the Thermal Conductivity

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