## 1 Introduction
Currently, due to the shortage of available energy sources and ongoing increases in energy consumption, energy costs are on an upward trajectory. Consequently, it is crucial to find alternatives to reduce energy use and price. During recent years, the addition of fibers to soil blocks as reinforcements or replacements for other constituents has increased enormously, mainly for political, environmental and economic reasons. Numerous types of natural fibers have been incorporated to soil-cement blocks to develop building material composites with great thermal performances [15; 16; 17; 18; 19; 20], which result in reducing heat transmission inside buildings, which could lead to decreased energy use of constructions utilities, including air conditioners. Others studies concerning thermal properties have highlighted that a large value of thermal conductivity is observed for bricks stabilized with cement [21]. Also, the increase in cement and lime content increases thermal conductivity [15; 26]. The future of \"green composites\" will be natural fiber-reinforced biopolymer materials, which have the potential to tackle sustainability challenges including environmental pollution and the shortage of natural resources. Traditionally, since ancient times, natural fibers have been incorporated into earnten building materials to improve composite performance, including ductility, toughness, tensile strength, and durability, as well as increasing its strength [5; 22; 23; 24] while reducing shrinkage and cracks. Due to their capacity to substitute synthetic fibers, and because of their global abundance, plant fibers have received specific interest for their application in building materials [22; 23]. Furthermore, some studies have concluded that increasing the fiber content leads to a decrease in the thermal conductivity of CEBs [15; 16; 27; 28; 29]. According to the literature [30], the mechanical strength is improved with the increase in fiber content due to the matrix's ability to glue the grains and fill the pore network, with low unit weight. Finally, fibers decrease the earth composite density, which has a number of benefits, including increased earthquake protection by reducing inertial forces and reduced thermal conductivity [31; 32; 33]. In the context of global warming, the cracking phenomenon due to desiccation that has already occurred in different soils is predicted to further emerge with high frequency [34; 35]. [PERSON] et al. used micron-sized X-ray computed tomography (Micro-CT) to investigate the dynamic evolution of drying-induced cracks and permeability in granite residual soil (GRS) over time (0 to 120 h). Their results showed that the average area/porosity ratio increased as the drying process progressed and that connected cracks propagated rapidly through the samples, while isolated cracks remained relatively unchanged. Moreover, the pore-diameter distribution of GRS indicated that the propagation of connected cracks was a key factor influencing soil cracking. The simulated permeability values were generally consistent with the measured values, indicating the accuracy of the seepage models. Both the experiments and numerical simulations showed that the desiccation process had a significant impact on the hydraulic properties of the soils [36]. This work is based on the investigation of the feasibility of combining Portland cement as a stabilizer and Juncus fibers (JF) as a reinforcement for the production of compressed earth blocks in order to improve their properties. Portland cement was used as a stabilizer of the CEBs, at proportions of 4%, 8%, and 12% by weight. The JF reinforcement were incorporated at different proportions, specifically 0%, 0.05%, 0.1%, 0.15%, and 0.2%. Experimental characterization was conducted to investigate the properties of the resulting CEB composites, including the density, ultrasonic pulse velocity, total water absorption, capillarity coefficient, dry and wet compressive strength, thermal conductivity, durability properties (erosion resistance, dry abrasion) and SEM micrographs.