Impact of Successive Layer Spraying of Polymer Binder on Hygroscopic Performance of Earth Walls in Humid Tropical Environments

The use of earth in tropical building is gaining increasing attention due to its natural ability to regulate humidity, which is essential for thermal comfort. This study evaluates the hygroscopic performance of an earth wall stabilized with hemp fibers and a polymer binder, applied through successive layer spraying via gravity-driven impregnation—a technique borrowed from the road and urban development sector. In this study, a plate measuring 60 cm in width, 90 cm in length, and 4 cm in thickness, produced using this process, was placed in small-scale experimental cells to investigate its influence on moisture regulation under real climatic conditions. Results indicate that, despite the use of a hydrophobic binder, the wall maintains effective hygroscopic regulation thanks to the stabilization technique. This research provides valuable insights into the role of polymer use in optimizing the hygroscopic properties of earth-based constructions, which is a key parameter for ensuring indoor comfort, particularly in humid tropical climates.