Sand and Soil Samples

Thermal Conductivity Tests of Sand and Soil Samples

Testing thermal conductivity of core samplesWe offer contract testing of sand and soil samples with our thermal conductivity meter TK04 using the needle probe method described in ASTM D5334-08 / ISO 22007-1. We assist with planning the measurements, taking or preparing the samples and with the correct interpretation of the results.

You send your samples or raw materials to our laboratory in Berlin, Germany, where we prepare the samples (if requested) and measure their thermal conductivity for you. Please request a quotation.

Moisture Content

Thermal conductivity vs. moisture content The thermal conductivity of sand and soil samples is determined by the thermal conductivities of the solid grains (the matrix) and of the pore filling. The pore filling of a dry material is air (thermal conductivity approx. 0.03 W/mK), the pore filling of a saturated material is water (thermal conductivity approx. 0.6 W/mK). Hence the thermal conductivity of a porous material increases with water content.

read moreread less

The maximum value (when the sample is saturated) can be five or six times the minimum value (when the sample is completely dry). The dependency is non-linear. Hence the moisture content of the samples must be known, or a well-defined moisture content must be achieved, before starting measurements. Depending on the purpose of the tests, we either determine the complete thermal conductivity vs. moisture curve (7 to 10 measurements at different moisture contents), or the minimum value (i.e. the dry sample is tested), or the maximum value (i.e. the saturated sample is tested).

Density and Compaction

Compacted sand samples with measuring positions for the needle probe As the matrix thermal conductivity of sand is higher than the thermal conductivities of air and water, the thermal conductivity of sand and soil samples increases with decreasing pore volume. The pore volume depends on the density or compaction of the material. When taking samples in the field, take care not to affect the structure of the material in order to avoid influencing the results. When preparing samples in the laboratory, always use the same compaction which will be used later for the planned application.

Testing Thermal Conductivity Yourself

If you wish to test thermal conductivity yourself, please see our application note (PDF) Testing thermal conductivity of soil samples for additional details and recommendations for probe choice, sample preparation and measurements.