Investigation of mechanical and durability properties of bio-calcium-stabilized tropical soils with Grewia bicolor juice for compressed earth block production

Freshly extracted Grewia bicolor juice (GBJ) was assessed as a stabilizing agent for compressed earth blocks composed of lateritic, red, and clay soils. The evaluation involved replacing 0–20% of the total mixing liquid mass with GBJ, selecting 5%, 10%, and 15% concentrations based on 14-day unconfined compressive strength results. The stock extract exhibited 11.11% total solids and an average pH of 5.19 at 24.8 °C. Local EDXS analysis of the Grewia material identified the presence of C, O, and Ca, with 14.29 atomic% Ca, characterizing the solid region analyzed rather than the dissolved extract composition. Comparative SEM fields revealed compact aggregates in treated soils, although acquisition differences limited quantitative pore comparisons. After 100 days of ambient conditioning, GBJ enhanced block compressive strength by 6.7–15.9% and dry density by 0.7–4.9%, while flexural strength decreased by 11.0–29.6%. Abrasion loss was reduced by 6.8–86.6%, and water absorption decreased by 23.2–55.1%; however, treated clay blocks still exhibited 25.62% absorption. Red soil with 10% GBJ achieved the highest ranking under an equal-weight assessment of compression, abrasion, and absorption. The findings suggest particle association and organic–mineral binding, though they do not identify hydrate products or establish reactive calcium loading. The study highlights soil-specific advantages alongside a flexural penalty and residual moisture vulnerability, advocating for dosage selection based on multiple performance criteria.