Thermal characterization of adobes stabilized with natural fibers, Hyperrhénia Hirta and Stipa Offneri, using the asymmetric hot plate method coupled with the quadripolar formalism

The present study aims to thermally characterize adobes stabilized with natural fibers. The fibers of Hyperrhénia Hirta and Stipa Offneri are empirically mixed with laterite for the production of adobes, particularly in Kila, in the Mogodé district, located in the Far North of Cameroon. Scientific data regarding the impact of these fibers on the thermal properties of adobes remain limited. For the experiments, soil collected from an adobe production area in Mogodé was mixed with different proportions of fibers, ranging from 0–1% in increments of 0.2%, to produce specimens with dimensions of 10×10×3 cm³. The asymmetric hot plate method coupled with the quadripole formalism was utilized for measuring the thermal characteristics of the samples. The results show that the incorporation of these fibers contributes to improving the thermal properties of the earthen blocks. A significant decrease in thermal conductivity was observed with increasing fiber content, reaching a reduction of 33.8% for Hyperrhénia Hirta fibers and 43% for Stipa Offneri fibers. The other thermal properties (diffusivity, effusivity, and volumetric heat capacity) change in the opposite direction with increasing fiber content, confirming the enhancement of the thermal performance of the adobes. These results suggest that adobes stabilized with these fibers possess strong potential as thermal insulation materials. Consequently, these fibers could be used effectively in areas with high temperatures, particularly in the Far North of Cameroon.