Traditional soil stabilization techniques, such as cement and lime, are known for their menacing effect on the environment through heavy carbon emissions. Sustainable soil stabilization methods are grabbing attention, and the utilization of biopolymers is surely one among them. Recent studies proved the efficiency of biopolymers in enhancing the geotechnical properties to meet the requirements of the construction industry. The suitability of biopolymer application in different soils is still unexplored, and the carbon footprint analysis (CFA) of biopolymers is crucial in promoting the biopolymers as a promising sustainable soil stabilization method. This study attempts to investigate the out-turn of cross-linked biopolymer on soils exhibiting different plasticity characteristics (Medium & High compressibility) and to determine the Embodied carbon factor (ECF) for the selected biopolymers. Guar (G) and Xanthan (X) biopolymers were cross-linked at different proportions to enhance the geotechnical properties of soils. Atterberg’s limits, Compaction characteristics, and Unconfined Compressive Strength were chosen as performance indicators, and their values were analyzed at different combinations of biopolymers before and after cross-linking. The test results have shown that Atterberg’s limits of the soils increased with the addition of biopolymers, and it is attributed to the formation of hydrogels in the soil matrix. Compaction test results reveal that the Optimum Moisture Content (OMC) of biopolymer-modified soil increased, and Maximum Dry Density (MDD) reduced due to the resistance offered by hydrogel against compaction effort. Soils amended with biopolymers and cured for 14, 28, and 60 days have shown an appreciable improvement in Unconfined Compressive Strength (UCS) results. Microlevel analysis was carried out using SEM (Scanning Electron Microscopy) and FTIR (Fourier-transform infrared spectroscopy) to formulate the mechanism responsible for the alteration in targeted performance indicators due to the cross-linking of biopolymers in the soil. The embodied energy in the production of both Guar and Xanthan biopolymers was calculated, and the obtained ECF values were 0.087 and 1.67, respectively.

This study investigates the influence of guar gum (G), xanthan gum (X), and their cross-linked blend on the shear strength and consolidation characteristics of soils with contrasting plasticity and mineralogical characteristics. Direct shear, one-dimensional consolidation, constant head permeability tests, SEM and XRD analyses were conducted on high-plastic clay, medium-plastic clay, and sand-dominant soil treated with standalone (2G, 2X) and combined (1G+1X) biopolymer dosages under curing periods up to 28 days. The cross-linked treatment produced the most consistent overall improvement. In the high-plasticity soil, cohesion increased from 56.87 to 81.39 kPa and the friction angle increased from 7.8° to 10.5°. In the medium-plasticity soil, cohesion increased to 77.47 kPa and the friction angle reached 12.2°. In the sand dominant soil, the friction angle increased from 39.1° to 42.9°, while cohesion increased from 12.74 to 23.53 kPa. At 800 kPa, the cross-linked blend reduced the void ratio to 0.18 and 0.14 in the high- and medium-plasticity soils, respectively. Hydraulic conductivity decreased to 8.45 × 10⁻⁹, 8.21 × 10⁻⁹, and 9.10 × 10⁻⁵ cm/s in the three soils. These improvements are attributed to polymer bridging, hydrogen bonding, pore filling, hydrogel formation, and mineralogy-dependent soil-polymer interactions. The findings demonstrate the potential of cross-linked biopolymers as sustainable stabilizers for geotechnical applications.