Combination of the unifying model for the effective thermal conductivity of isotropic, porous and composite geomaterials

A fixed-parameter ETC predictive model was proposed using simple combinatory rules, based on which the triweighted means (arithmetic, geometric and harmonic) of tri-upper and lower ETC bounds (Series-Parallel, two forms of Maxwell-Eucken, and Co-Continuous-Effective Medium Theory) can be unified. Theoretical analyses firstly explain the relative success of the weighted arithmetic combination between series and parallel models in the literature so far. Experimental validation was then conducted and the results indicate that the presented combinatory models can be well fitted to most ETC data of internal porosity geomaterials by adjusted values of weighting parameter f. However, this type of combinatorial model would give more uncertainty when applied to external porosity geomaterials such as granular sands. Finally, some meaningful analyses, conclusions and research perspectives were obtained, drawn and opened for future investigations in this field.