Utilizing Sodium Alginate Biopolymer for Enhancing Montmorillonite- Enriched Clayey Subgrade

Abstract

Soil stabilization is the optimal approach that can improve various soil properties, including permeability, compressibility, strength, and durability. It is widely known that chemical stabilization can improve the mechanical characteristics of problematic soils. This work examined sodium alginate (SA) as a sustainable bentonite clay stabiliser to improve a high-plasticity clay. We soaked sodium alginate at different concentrations (0%, 0.5%, 1%, 1.5%, 2%, and 3%) to stabilise the bentonite clay of the compacted soil samples, utilising techniques such as standard proctor and unconfined compressive strength (UCS), scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Adding sodium alginate in different amounts (0.5%, 1%, 1.5%, and 2%) lowered the optimum moisture content (OMC) and raised the maximum dry density (MDD). Following 0, 14, and 28 days of curing, the UCS of stabilized samples were evaluated. It was found that adding 2% sodium alginate to bentonite clay raised both the maximum dry density and the optimum moisture content. The soil stabilized using the soaking technique displayed a higher 14-day UCS at the ideal sodium alginate content of 2% compared to the untreated soil. The microstructural investigation showed that the increase in strength was due to sodium aluminosilicate hydrate, a new cementitious material that filled in the pores and made the bonds between particles stronger. This research's conclusions will support bentonite clay's stability through the use of environmentally acceptable sodium alginate in subgrade applications.