One-part alkali-activated soil stabilization with sodium metasilicate: Mechanical-geochemical-mineralogical characterization

Abstract

A shift towards environmental sustainability is an emerging trend in the modern construction industry, and soil stabilization is no exception. Environmental and economic constraints associated with traditional cement have led to a renewed research focus, particularly on the development of alkali-activated materials (AAMs), a cost-effective and environmentally sustainable stabilization method. Traditional AAM synthesis involves the activation of industrial byproducts in an alkaline solution, which poses challenges in transporting, storing, and handling large quantities of liquid alkaline activators in the field. To address these challenges and enable the large-scale application of AAM-based soil stabilization, a one-part alkali-activation method is proposed, utilizing a dry powdered alkaline activator. This study aims to evaluate the potential of dry sodium metasilicate (SM), used in conjunction with Class C fly ash, Class F fly ash, and ground granulated blast-furnace slag, to stabilize weak clayey soils with medium-to-high initial moisture content. Towards that end, five stabilizer mixes with and without SM were designed to stabilize natural soil at different initial moisture states. The engineering properties of these blends were assessed through unconfined compressive strength (UCS) testing, and a relationship between the initial water content of the soil, stabilizer dosage, and the desired UCS for the alkali-activated mixtures was developed. Furthermore, the microstructure of these blends was characterized through geochemical and mineralogical analyses, including pH measurement, X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), and scanning electron microscope (SEM) imaging. This study demonstrates the feasibility of using dry SM to create one-part AAM, which holds promise for stabilizing weak soils in various transportation infrastructure systems, including roadways, airfield pavements, and railways.