Effective thermal conductivity of clayey aerated concrete in the dry state: experimental results and modelling

The aim of this study was to determine the effective thermal conductivity of a new insulating building material, called clayey aerated concrete (CAC), when used in a dry state. A series of six mixtures having different porosities obtained by adding aluminium powder to the clay-cement matrix was used in the investigation. The measurements of thermal conductivity have been performed inside a closely controlled climatic cell at ambient temperature (20±1 °C) using a `line source' method. The experimental results reveal that enhanced thermal performances can thus be obtained by the development of local materials, and their use in building insulation reveals very interesting properties as compared to other building materials. The study has been extended to the research of theoretical models capable of predicting the effective thermal conductivity of dry CAC considered as a two-phase system. Three models based on a geometric mean approach (Asaad model, Veerendra and Chaudhary model) and a effective continuous medium approach (Pande and Chaudhary model) were used. In order to predict effective thermal conductivity of elaborated material using such models, a correction term has been empirically determined and introduced in these models, taking into account the effect of a higher ratio of the thermal conductivity (_s/_f). A very good agreement has been observed between the analytical and experimental results, thereby confirming the model's ability to predict the effective thermal conductivity of dry CAC.