Utilization of Biomass Ash in Cement-Based Materials

Biomass ash—comprising fly ash and bottom ash generated from the combustion of agricultural residues, wood and forest by-products—has emerged as a promising supplementary cementitious material in concrete and mortar formulations. Its global abundance and the environmental imperative to reduce carbon emissions drive interest in ash utilisation to replace a proportion of Portland cement, thereby lowering embodied CO₂. The chemical composition of biomass ash typically includes silica, alumina, calcium, alkali metals and unburnt carbon, the proportions of which depend on biomass source and combustion technology. When finely milled or thermally and chemically activated, these ashes exhibit pozzolanic or latent hydraulic reactivity, contributing to strength development and durability through secondary hydrate formation. Techniques such as alkali activation, mechanochemical treatment and controlled curing enhance reactivity and mitigate heavy-metal leaching. Practical applications range from partial cement replacement in structural mortars to the production of alkali-activated composites, offering pathways for waste valorisation, resource conservation and improved material performance in sustainable construction.

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Utilization of Biomass Ash in Cement-Based Materials publication trend

The graph below shows the total number of articles in utilization of biomass ash in cement-based materials across all publications each year (not limited to Nature Index journals).

Technical terms

Biomass ash: Incombustible residue remaining after the thermal treatment of organic biomass, composed of fine particles (fly ash) and coarser fractions (bottom ash).

Supplementary cementitious material (SCM): A finely divided mineral additive that reacts chemically with calcium hydroxide in hydrated cement to form additional cementitious compounds.

Pozzolanic reactivity: The ability of silica- or alumina-rich materials to react with calcium hydroxide in an alkaline environment, forming strength-giving calcium silicate hydrates.

Alkali activation: The process of binding aluminosilicate precursors with alkaline solutions to produce geopolymeric or alkali-activated binders.

Mechanochemical activation: Enhancement of material reactivity through mechanical energy input (e.g. milling) that increases surface area and structural disorder.

Mineral carbonation: A chemical process by which carbon dioxide reacts with metal oxides (commonly calcium or magnesium) to form stable carbonate minerals, enabling CO₂ sequestration.

References

1. Wood fly ash and blast furnace slag management by alkali-activation: Trace elements solidification and composite application. Journal of Environmental Management (2024).
2. Mechanochemical activation for improving the direct mineral carbonation efficiency and capacity of a timber biomass ash. Journal of CO2 Utilization (2023).
3. Technical and environmental performance of lower carbon footprint cement mortars containing biomass fly ash as a secondary cementitious material. Resources Conservation and Recycling (2018).