Geopolymer Stabilization of Expansive Soils

Expansive soils, typically rich in smectitic clays, pose a significant challenge for infrastructure due to their pronounced volume change with moisture fluctuations. Geopolymer stabilization offers a sustainable alternative to conventional binders by exploiting the alkali activation of industrial by-products such as fly ash, ground granulated blast furnace slag (GGBFS) and volcanic ash. This approach generates amorphous aluminosilicate networks—commonly referred to as geopolymers—that bind soil particles, reduce plasticity and suppress swelling–shrinkage cycles. The resulting soils exhibit enhanced unconfined compressive strength, improved durability under wet–dry and freeze–thaw cycles and reduced environmental footprint compared with Portland cement. Key factors influencing performance include the type and proportion of precursor materials, alkaline activator concentration, curing regime and soil mineralogy. Practical applications range from pavement subgrades and embankment works to foundation improvement in regions prone to differential settlement and heave. Global research efforts have demonstrated the potential for local industrial wastes to be valorised, reducing both carbon emissions and landfill burdens.

Research from Nature Portfolio

No recent Nature Portfolio content available.

Geopolymer Stabilization of Expansive Soils publication trend

The graph below shows the total number of articles in geopolymer stabilization of expansive soils across all publications each year (not limited to Nature Index journals).

Technical terms

Expansive soils: Clay-rich soils that undergo significant volume change with moisture variation, leading to heave and settlement.

Geopolymer: An inorganic polymer formed by alkali activation of aluminosilicate precursors, producing a cementitious matrix.

Alkali activation: The process of dissolving aluminosilicate materials in a high-pH solution to form geopolymeric gels.

N-A-S-H gel: Sodium aluminosilicate hydrate, the primary binding phase in many geopolymers.

C-(A)-S-H gel: Calcium aluminosilicate hydrate, a calcium-enriched binding phase augmenting geopolymer strength.

Unconfined compressive strength (UCS): The maximum axial load per unit area a soil specimen can withstand without lateral support.

Atterberg limits: Standardised water-content thresholds (liquid and plastic limits) defining transitions in soil consistency.

Shrink–swell capacity: The potential of clayey soils to undergo volumetric change upon wetting and drying.

References

1. Clayey soil stabilization using alkali-activated volcanic ash and slag. Journal of Rock Mechanics and Geotechnical Engineering (2022).
2. Shear strength and life cycle assessment of volcanic ash-based geopolymer and cement stabilized soil: A comparative study. Transportation Geotechnics (2021).
3. Potential of Soil Stabilization Using Ground Granulated Blast Furnace Slag (GGBFS) and Fly Ash via Geopolymerization Method: A Review. Materials (2022).
4. Performances of Using Geopolymers Made with Various Stabilizers for Deep Mixing. Materials (2019).