OPTIMISTHE

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 use of thermal energy storage composite materials allows passive cooling and heating in buildings, yielding substantial energy savings. The purpose of this study is to develop and test a new phase change material (PCM) composite by loading expanded perlite (EP) with paraffin (RT27) to form plaster composites. The leakage tests allowed to unfold the optimal RT27 loading rate. To avoid paraffin leakage out of the composite structure, a waterproof product, Sikalatex® (SL), was used to coat the RT27/EP composite before mixing it with plaster. Thermal properties of RT27/EP/SL integrated in plaster were assessed. The effect of aluminum powder insertion on enhancing the composite thermal properties, was investigated. Paraffin loading rate was 60% by direct impregnation. FTIR analyses proved that the produced composites showed a good chemical compatibility between different components. DSC analyses revealed that composites have suitable energy storage capacities of 51.57 ± 0.01 and 49.95 ±0.15 kJ.kg-1 for RT27/EP/SL and RT/EP/SL/Al, respectively. These composites are suitable for indoor temperature regulation. Thermal cycling tests showed a good thermal stability of plaster PCM composite. Thermal conductivity of plaster composite containing 50% wt of RT27/EP/SL/Al composite was increased by 80% and 68% at 12°C and 40°C respectively compared with the aluminum free composite.

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.