Effect of execution technique on durability of alkali-activated crust for wind erosion mitigation

Abstract

Wind-induced soil loss is a critical concern in arid and semi-arid regions, where vegetation-based stabilization is often ineffective. This study evaluates alkali-activated slag as a surface treatment for silty sand using three application strategies: (i) one-phase (pre-mixed slurry of slag and NaOH), (ii) two-phase (NaOH solution sprayed onto dry slag–soil mix), and (iii) three-phase (dry-mixed solid NaOH and slag, followed by water spraying). Samples were exposed to one year of real-field conditions across four climatic seasons. Mechanical and microstructural evaluations were conducted, including wind tunnel erosion testing under various wind velocities and particle bombardment, penetrometer tests for surface strength, and XRD, EDS, and FE-SEM analyses. Results indicate that the one-phase method achieved the highest erosion resistance and surface strength, attributed to more homogeneous gel formation and higher amorphous content, while two- and three-phase methods exhibited heterogeneous microstructures and reduced performance. Notably, even under the most aggressive erosion conditions, the treated samples retained substantial protection after one year of exposure, with erosion rates reduced by 86.7 % in the one-phase method, 83.6 % in the two-phase method, and 80.7 % in the three-phase method compared to untreated soil. Although the one-phase method exhibits slightly higher execution-stage CO 2 emissions than the other methods, its superior durability and long-term erosion resistance suggest that the small increase in operational footprint is justified for large-scale applications. These findings highlight the critical role of application method in optimizing alkali-activated binder performance and underscore the potential of slag-based surface treatments for sustainable, long-term wind erosion control.

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