Exploring the thermal and mechanical properties of plasters reinforced with argan nut shells: New composites for energy efficiency applications

The use of natural materials derived from argan nut shell waste in the construction and thermal insulation activities offers several technical, economic and environmental advantages. This work presents an experimental study investigating the impact of adding ground argan nut shells (ANS) on the plaster’s thermomechanical properties. The aim is to design new environmentally-friendly composites, which could be used primarily for energy-efficiency applications in buildings. These new materials were prepared by incorporating different proportions of ANS grains into the mix, ranging from 0 % to 20 %. Two grain sizes were studied: fine particles (d $<$ 0.5 mm) and coarser particles (2.25 mm $<$ d $<$ 4 mm). The EI700 cell, known as the two-box method, was used to determine the thermophysical properties, while the mechanical characterization was carried out using bending tests (H10KL cell). However, the thermophysical tests carried out showed that increasing the particle size and the proportion of ANS in the base matrix considerably improved its thermal properties. Specifically, the density, thermal diffusivity and thermal conductivity were decreased by around 2.92 %, 68.06 % and 40.45 %, respectively. In addition, mechanical tests have shown that this process leads to a reduction in flexural strength, which has dropped from 3.15 MPa to 2.29 MPa, a reduction of 27.30 %. Nonetheless, this reduction remains acceptable according to the European construction standard EN 13279-2. The microscopic study (SEM) revealed perfect compatibility between the aggregates and the plaster granules and justified the results obtained by increasing the porosity of the conventional matrix. This research demonstrates that argan nut shells may be used to reinforce building materials, improving the energy efficiency of buildings while reducing their environmental impact.