Events

N. Dujardin, T. Salem, V. Feuillet, M. Fois, L. Ibos, C. Poilâne, R. Manuel (2020), Measurement of pore size distribution of building materials by thermal method, Construction and Building Materials, 245:118417, DOI: 10.1016/j.conbuildmat.2020.118417.

T.-T. Ha, V. Feuillet, J. Waeytens, K. Zibouche, S. Thébault, R. Bouchié, V. Le Sant, L. Ibos (2020), Benchmark of identification methods for the estimation of building wall thermal resistance using active method: numerical study for IWI and single-wall structures, Energy and Buildings, 224:110130, DOI: 10.1016/j.enbuild.2020.110130.

A. François, L. Ibos, V. Feuillet, J. Meulemans (2020) Estimation of the thermal resistance of a building wall with inverse techniques based on rapid in situ measurements and white-box or ARX black-box models, Energy and Buildings, 226:110346, DOI: 10.1016/j.enbuild.2020.110346.

A. François, L. Ibos, V. Feuillet, J. Meulemans (2021), In situ measurement method for the quantification of the thermal transmittance of a non-homogeneous wall or a thermal bridge using an inverse technique and active infrared thermography, Energy and Buildings, 233:110633, DOI: 10.1016/j.enbuild.2020.110633

The present work focuses on the study of the thermophysical properties of low porous insulation materials. In peculiar, we investigate the pore structure of composite materials and cements by thermal method. This method, adapted for fragile materials, is based on an existing model which allows the determination of pore size distribution. Firstly, the existing analytical model is presented. The thermal conductivity is modeled by assimilating the studied medium to N fluid phases and one solid phase in series / parallel. Secondly, some extensions to this model are proposed. In particular, we show that in the case of a single pore size, it is possible to obtain a finer pore size distribution by means of a normal law. We also show for the first time that the normalization of the thermal conductivity is an interesting way to study the pore size distribution of a material without knowing the overall porosity rate (which strongly depends on the method used). Furthermore, this model and its extensions have been successfully applied to different kinds of materials (plant fiber composites and cements). Fibers reinforced composites have one class of pores around 30 – 60 lm. Chemical treatments do not affect this pore size. Cements show a macroporosity (around 20 lm) which is often underestimated.

The present work focuses on the study of the thermophysical properties of Posidonia Oceanica natural fibers in order to investigate the potential of their use as loose-fill thermal insulation material in the Mediterranean construction. 24 samples were prepared. Bulk densities were varied from 17 kg m-3 to 155 kg m-3. Chemical alkali treatments with various conditions were applied to these fibers. The influence of treatments and of density on morphological and thermophysical properties of samples was evaluated. The surfaces were examined by using scanning electron microscopic. The thermal measurements were performed with the Hot Disk thermal constants analyzer. Results have shown that thermal conductivity decrease when density decreases until an optimum. After that, it increases as the density is reduced. Furthermore, regarding thermal conductivity, it was found out that the effect of chemical treatment is not significant mainly at the low densities. A very slight improvement was found at high densities with treated fibers, mainly the treatment that consists of immerging fibers twice in 2% sodium hydroxide solution during 2 h at 80 °C. Higher mass heat capacity was observed with this same treatment. Additionally, it was revealed in this study that Posidonia-Oceanica fibers have thermal conductivity and thermal diffusivity close to conventional insulation materials and higher mass heat capacity that reached 2533 J kg-1 K-1.

Abstract High energy consumption in the building sector appeals for the implementation and the improvement of innovative approaches with low-environmental impact. The development of eco-friendly composites as insulating materials in buildings provides practical solutions for reducing energy consumption. Different mass proportions (2.5%, 10%, and 20%) of untreated and chemically treated palm fibers were mixed with (cement, water and sand) so as to prepare novel composites. Composites were characterized by measuring water absorption, thermal conductivity, compressive strength and acoustic transmission. The results reveal that the incorporation of untreated and chemically treated date palm fibers reduces novel composites’ thermal conductivity and the mechanical resistance. Thermal measurements have proved that the loading of fibers in composites decreases the thermal conductivity from 1.38 W m−1 K−1 for the reference material to 0.31 W m−1 K−1 for composites with 5% of treated and untreated fibers. The acoustical insulation capacity of untreated palm fiber-reinforced composites (DPF) was the highest at 20% fiber content, whereas treated palm fiber-reinforced composites (TPF) had the highest sound insulation coefficient for fiber content lower than 10%. Compressive strength, thermal conductivity and density correlation showed that only chemically treated fiber-reinforced composites (TPF) are good candidates for thermal and acoustic building insulations.