Strength Enhancement of High Plastic Clay Using Alstonia Boonie Gum as an Additive

Abstract

High plastic clay soils are problematic due to their expansive nature, with high shrinkage and swelling behaviours that cause damage to infrastructure. This study investigated the potential of using Alstonia boonei gum, a natural biopolymer, as an eco-friendly soil stabilizer for problematic high plastic clay soils in the Niger Delta region of Nigeria. Soil samples were collected from two locations in Bayelsa State and laboratory tests evaluated the effects of varying gum dosages (0.1-1.0%) on unconfined compressive strength, permeability, and swell pressure. Microstructural analysis was also conducted. Preliminary results showed the biopolymer effectively modified soil microstructure and minerals, with strength increases up to 60% at a 0.5% dosage compared to untreated soils. Permeability reductions of 5070% and swell pressure decreases of 25-40% were also achieved at this dosage. Optimal effects occurred with wet mixing and moist curing. Life cycle analysis indicated the renewable and biodegradable nature of the biopolymer reduces environmental impacts compared to traditional stabilizers. This research demonstrated Alstonia boonei gum's potential to enhance problematic soil properties through microstructural changes, presenting opportunities for sustainable development in Nigeria.

Keywords — Alstonia boonei gum, Soil stabilization, Expansive clay, Biopolymer, Sustainable

geotechnics