Strength and Fracture Behavior of Rammed-Earth Materials

Rammed-earth (RE) structures are becoming popular because of their sustainability, environment-friendly, and economic advantages. Various studies have investigated the mechanical behavior and energy performance of rammed-earth materials. However, little is known about their fracture behavior. In this study, the fracture properties of RE materials containing different percentages of various stabilizers were investigated using a modified wedge splitting test (WST). The stabilizers were cement, pozzolan, microsilica, glass fiber, guar gum, and phase change material (PCM). Additionally, the effects of these stabilizers on microstructure and phase composition were analyzed using scanning electron microscopy (SEM) and X-ray powder diffraction (XRD), respectively. The results indicated that cement and pozzolan, depending on the pozzolanic reaction, increased the strength of the microstructure while glass fibers led to internal confinement and high ductility that increased the fracture energy of RE materials. However, the phase change material and guar gum reduced the strength and fracture energy of the RE materials. Finally, a statistically significant correlation was obtained between specific fracture energy and other mechanical properties, pointing the way to proper approaches to improve crack resistance of rammed-earth materials.