Modelling and experimental determination of thermal properties of local wet building materials

Abstract

One of the greatest challenges in the construction sector throughout the world is the development of appropriate building materials that can reduce energy consumption. In this work, an investigation on the thermophysical properties of three wet composite building materials was carried out: the black pouzzolan, the red pouzzolan and sand cinder blocks. Experimental measurements were carried out on these three materials each with a water contentranging between 0 and 5%.Using an asymmetrical hot plate device, a transient method, the thermal effusivity and volumetric heat capacity were estimated experimentally with respect to water content. With the values of the mass specific heat capacity of pouzzolans, sand and cement separately measured by the Differential Scanning Calorimeter (DSC) method, the values of the volumetric heat capacity of these composite materials were evaluated according to their water content calculated from the theoretical developed model. The results obtained are in good agreement with those determined experimentally with the asymmetrical hot plate method (maximum standard deviations 5%). Results reveal that the thermal conductivity of red pouzzolan cinder blocks (e.g. λ=0.503Wm−1K−1 at 0% water content) and of black pouzzolan cinder blocks (e.g. λ=0.549Wm−1K−1 at 0% water content) are lower than that of sand cinder blocks (e.g. λ=0.875Wm−1K−1 at 0% water content). Results also show that pouzzolans cinder blocks have higher volumetric heat capacity than sand cinder blocks. These results further confirm that blocks based on pouzzolans are better insulator materials than sand blocks (usually uses) and can contribute significantly to the energy saving and thus reduce the GHG emission in the air-conditioning building.