Feasibility Study of Loess Stabilization with Fly Ash–Based Geopolymer

Loess, which primarily consists of wind-transported silt and clay particles, is widely distributed around the world, including the central Asia, central Europe, the northwestern and central United States, Alaska, and South America. The metastable structure of natural loess has resulted in construction delays and catastrophic failures. To explore the potential applications of soil improvement with green materials, this paper presents an experimental study of applying fly ash–based geopolymers for the loess stabilization. Two different precursors are employed to the investigation. It is found that potassium hydroxide renders a higher unconfined compressive strength than sodium hydroxide to the samples when the same fly ash/loess ratio is applied. This agrees with the results of the mechanical properties of the two different geopolymers. With an increasing fly ash/loess ratio, the compressive strength and Young’s modulus increase. The microstructural characterization unveils that a compact and stable microstructure has been developed in the stabilized loess. With the aid of energy dispersive X-ray spectroscopy and X-ray diffraction, it is observed that it is the binding effect of geopolymer gel that contributes to the improvements in the mechanical properties of stabilized loess samples.