Mechanical Activation of Fly Ash in Geopolymer Synthesis

Mechanical activation transforms the reactivity of fly ash—an abundant by‐product of coal combustion—by applying high‐energy milling or grinding to reduce particle size, increase surface area and alter amorphous content. These modifications accelerate the dissolution of aluminosilicate species during alkali activation, fostering rapid formation of a three‐dimensional network of sodium aluminosilicate hydrate gel. Enhanced reactivity enables geopolymer synthesis under milder curing conditions, reducing reliance on elevated temperatures and highly concentrated alkaline solutions, while delivering binders with superior early‐age strength, durability and a lower carbon footprint. Techniques such as ball milling, attrition milling and vibration milling impart distinct microstructural changes that govern geopolymerisation kinetics and ultimate performance. Recent advances highlight the capacity to tailor activation parameters for optimised mechanical properties, broaden construction applications and explore specialised functions such as radiation shielding.

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Mechanical Activation of Fly Ash in Geopolymer Synthesis publication trend

The graph below shows the total number of articles in mechanical activation of fly ash in geopolymer synthesis across all publications each year (not limited to Nature Index journals).

Technical terms

Fly ash: Fine aluminosilicate residue produced by coal combustion, used as a precursor in geopolymer synthesis.

Geopolymerisation: Chemical process in which aluminosilicate materials are activated by alkali solutions to form inorganic polymer binders.

Mechanical activation: High‐energy milling process that induces structural defects and increases surface area to enhance chemical reactivity.

N-A-S-H gel: Sodium aluminosilicate hydrate phase that constitutes the primary binding network in fly ash geopolymers.

Specific surface area: Total surface area of particles per unit mass, influencing dissolution rates and reaction kinetics.

Amorphous phase: Non‐crystalline material structure lacking long‐range order, often more reactive in geopolymer formation.

References

1. Preparation and Characterization of Nano structured Materials from Fly Ash: A Waste from Thermal Power Stations, by High Energy Ball Milling. Discover Nano (2007).
2. Mechanical-Chemical Activation of Coal Fly Ashes: An Effective Way for Recycling and Make Cementitious Materials. Frontiers in Materials (2019).
3. Reactivity of fly ashes milled in different milling devices. REVIEWS ON ADVANCED MATERIALS SCIENCE (2019).
4. Synthesis of Geopolymers from Mechanically Activated Coal Fly Ash and Improvement of Their Mechanical Properties. Minerals (2019).
5. Synthesis of Fly Ash-Based Geopolymers: Effect of Calcite Addition and Mechanical Activation. Minerals (2020).
6. Geopolymers Based on Mechanically Activated Fly Ash Blended with Dolomite. Minerals (2021).
7. An Alternative Radiation Shielding Material Based on Barium-Sulphate (BaSO4)-Modified Fly Ash Geopolymers. Gels (2022).