STABILIZATION OF LOCAL SOIL WITH VARIOUS BINDING MATERIALS AND OPTIMIZATION OF A CEMENT–FLY ASH COMPOSITION

Abstract

The use of local soils in road base structures requires a scientifically justified selection of a binding material, since stabilization efficiency depends on the soil properties, the type and content of the binder, moisture conditions, and curing conditions. The aim of this study was to comparatively evaluate the effectiveness of stabilizing local soil with bitumen, lime, and cement, to determine the most effective binder, and to assess the possibility of reducing cement consumption by partially replacing it with thermal power plant fly ash. The study considered mixtures containing 5, 8, and 10% quicklime, as well as 8, 10, and 12% cement. The compressive strength and bulk density of the specimens were determined after 7 and 28 days of curing. When BND 70/100 bitumen was used, its high viscosity prevented the production of a homogeneous mixture. Among the main binders, the highest strength values were obtained with 12% cement, reaching 11.533 MPa after 7 days and 18.287 MPa after 28 days.

This composition was selected as the reference mixture for subsequent optimization of the cement–fly ash system. According to the results, the most promising composition contained 10% cement and 2% thermal power plant fly ash, with compressive strength values of 10.707 and 17.840 MPa after 7 and 28 days, respectively. The obtained results demonstrate the practical feasibility of reducing cement consumption while maintaining a high strength level of the stabilized soil.