The measurement of the thermal conductivity of solid aggregates using the transient plane source technique

Abstract

In predicting the overall thermal conductivity of composite porous structures such as building materials or soils, the thermal conductivities of their solid components must be known in order to apply some theoretical models. Horai proposed a method to determine the thermal conductivity of solid particles. The material under study is first ground to a fine powder. This powder is then carefully saturated with a fluid and the thermal conductivity of this mixture is measured using the `needle probe' method. Finally, the conductivity of the solid phase is evaluated using a mixing-law model, namely the mean of the so-called `Hashin and Shtrikman bounds'. We have introduced a slightly different version of this method that uses the `transient plane source' (TPS) technique recently developed by Gustafsson for simultaneously measuring both the thermal conductivity and the thermal diffusivity of solids or fluids. An adapted experimental device has been designed and our approach has been validated through measuring, at room temperature, the thermal conductivities of the well-known minerals quartz, calcite and kaolinite. Afterwards, while considering that our method had become fully operational, we studied the thermal conductivity of the solid aggregates of a light-weight, energy-saving concrete whose solid phase is a mixture of natural clay, hardened cement paste and wood aggregates in various proportions.

Effect of Thermoplastic Aggregates Incorporation on Physical, Mechanical and Transfer Behaviour of Cementitious Materials

“…The theoretical basis of this technique has been discussed by various authors [18,19]. The experimental device used in this study is composed of transient plane source (TPS) element, a power supply stabilised in tension, a wheatstone bridge, an acquisition power station and a microcomputer for the data control and processing.…”

Effective thermal conductivity of moistened insulation materials as a function of temperature

“…The free water saturation content (u fs ) and the moisture storage function (u(/)) are the most important characteristics. For the above mentioned materials only few publications may be found in the literature [26,27]. The pore fraction and pore size distribution and the density of the solid are measured according to the standards using mercury porosimetry (DIN 66133, [28]) or helium pycnometry (DIN 66135, [29]), respectively.…”

“…As has been demonstrated by Faust (see [26]), the results obtained by simplified experiments show good agreement with measured results obtained with experimental set-ups according to DIN specifications. The density and the thermal conductivity of the solid materials, listed in Table 3, are available in the literature (see [12,26,27,30,31] or [32]). …”

Determination of Bending and Axial Compression Young’s Modulus of Cellular Mortar Exposed to High Temperatures

“…For this research project, the foam density ranged between 58 kg/m 3 and 63 kg/m 3 was used for the production of cellular mortar. It was used to mix with fresh mortar therefore the wet density of the mortar can be controlled via rate of air bubbles generated in the cement paste mix [18] …”