TRANSFORMATION OF LOESS SOIL MECHANICAL PROPERTIES AND ITS EFFECT ON FOUNDATION BEARING CAPACITY: A COMPARATIVE IMRAD-BASED ANALYSIS OF BIOSTABILIZATION AND GEOPOLYMER METHODS

Abstract

Loess soils in the arid regions of Uzbekistan are characterized by high porosity, metastable structure, and pronounced susceptibility to hydro-collapse under wetting, which reduces foundation reliability and increases the risk of differential settlement. The aim of this study was to evaluate how microbiologically induced calcite precipitation (MICP) and geopolymer injection change the physical and mechanical properties of loess soils and, consequently, influence foundation bearing capacity. The study was designed as a comparative analytical review structured according to IMRAD principles. Peer-reviewed publications on loess geochemistry, land degradation in Uzbekistan, MICP, enzyme-induced carbonate precipitation, and geopolymer stabilization were synthesized, and their engineering implications were interpreted through classical bearing-capacity concepts. The analysis shows that MICP strengthens loess by forming calcite bridges at particle contacts, increasing apparent cohesion and internal friction while reducing permeability and wetting sensitivity. Geopolymer injection provides rapid setting, high chemical resistance in sulfate- and salt-affected soils, and a lower carbon footprint than ordinary Portland cement systems. Both methods are capable of improving the deformation response of collapsible foundations, but their domains of optimal application differ: MICP is better suited to environmentally sensitive or heritage sites, whereas geopolymer systems are preferable when rapid local reinforcement and saline resistance are critical. The study concludes that the transition from cement-intensive stabilization to bio-based and alkali-activated technologies is scientifically justified for arid loess terrains, although field-scale validation under the hydrogeological conditions of the Samarkand region remains necessary.