Development of high-strength rammed earth walls with alkali-activated ground granulated blast furnace slag (GGBFS) and waste tire textile fiber (WTTF) as a step towards low-carbon building materials

Abstract

Rammed earth (RE) structures are cost-effective and eco-friendly substitutes for low-rise buildings, but their low compressive and tensile strengths are a concern. Cement stabilization is often used to improve these properties, but this practice has negative environmental consequences. This study investigates the use of green alkali-activated mortar made with industrial waste materials, including ground granulated blast furnace slag (GGBFS) and waste tire textile fiber (WTTF), as a sustainable alternative to cement. The study involves testing the compressive and tensile strengths of the modified mortar under different climatic conditions (i.e., hot-dry, moderate, and cold curing environments). The results showed that the best improvement performance of the modified specimens in terms of both compressive and tensile strengths was obtained in hot-dry and moderate conditions, particularly GGBFS-based geopolymers, as confirmed by Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) analyses. In addition, the tensile strength of the specimens is notably enhanced by the addition of WTTF as a reinforcing agent. The change in the failure modes and the brittleness index values of the modified samples indicated the ductility characteristics, particularly in the hot-dry condition. Moreover, although reinforcing with WTTF remarkably increases the soil ductility, it is shown to barely affect the elastic modulus.