Research on sustainable alternatives to conventional soil stabilization has promoted the use of natural biopolymers as partial substitutes for cementitious binders. This study presents a mechanical and microstructural comparison between poorly graded Colombian sand stabilized with guar gum (GG) and Type III Portland cement. GG was incorporated at 0.25–1.00% with curing periods of 28 and 90 days, while cement contents ranged from 3 to 9% with 7 days of curing. A total of 108 cylindrical specimens were tested using unconfined compressive strength (UCS) and SEM–EDS analyses. Results show that both binders significantly improve soil strength, although cement exhibits a steeper strength gain due to hydration processes. GG-treated samples reached a maximum UCS of 470 kPa at 90 days, representing an increase of approximately 40% compared to 28 days and showing comparable performance to 5% cement. The porosity/binder index (η/Biv) demonstrated a strong correlation with UCS (R2 > 0.91), confirming its predictive capability. Microstructural analysis revealed the formation of C–S–H and ettringite in cement-treated samples, while GG-treated soils exhibited hydrogel bridges and the presence of pores that may influence particle bonding. Overall, the results demonstrate the technical feasibility of GG as a sustainable soil stabilization alternative.
Baldovino et al. (Wed,) studied this question.