Volcanic ash materials (such as volcanic ash, fly ash, silica fume, rice husk ash, etc.) exhibit unique properties due to their chemically reactive components and microstructures. They play an irreplaceable role in the fields of construction materials, environmental engineering, geological restoration, and tailings processing equipment applications. The main properties and mechanisms of action are as follows:

1.Activity components (SiO₂ and Al₂O₃): typically 60–90%. In an alkaline medium (such as Ca(OH)₂ produced during cement hydration), the pozzolanic reaction occurs:

SiO₂ + Ca(OH)₂ + H₂O → C-S-H gel.
This nano-scale (10–50nm) C-S-H gel efficiently fills pores and densifies the material, improving its compactness.

2.Strength development: 28-day compressive strength increases by 15–30% when 20% fly ash replaces cement; for the long term, 90 days afterwards, the degree of pozzolanic reaction exceeds 80%. The strength growth is 2× that of pure cement systems.
This phenomenon is particularly desirable in tailings processing equipment, where structural components must be strong and durable.

1.Particle filling: Volcanic ash particles, mostly < 45 μm (with silica fume as small as 0.1–0.3 μm), fill voids between cement grains, reducing total porosity by 5–8%.
This densification weakens the interfacial transition zone (ITZ) — its thickness drops from 40 μm to 15 μm — thereby inhibiting crack initiation and propagation.
Such properties are crucial when designing tailings processing equipment components subject to heavy loading.

2.Pore structure refinement: The proportion of large capillary pores (> 50nm) drops by nearly 50%.
This results in improved freezing resistance (mass-loss < 3% after 300 freezing-thaw cycles) and permeability resistance (permeability drops below 1 × 10^{-12} m/s), desirable for tailings processing equipment exposed to harsh service conditions.

1.Low-carbon and waste utilization:
Every ton of fly ash replacing cement cuts CO₂ emissions by 0.6–0.8 tons.
This provides an opportunity for large-scale utilization of industrial waste in tailings processing equipment, reducing waste disposal and conserving resources.

2.Chemical resistance:
The pozzolanic reaction depletes Ca(OH)₂ and inhibits the formation of expansive ettringite (< 0.1% expansion), improving resistance to sulfate attack.
Furthermore, chloride diffusivity drops to 1 × 10^{-13} m²/s due to formation of Friedel’s salt (forming from Al₂O₃ and Cl¯), extending service life for tailings processing equipment in aggressive environments.

3.Hydration heat control:
For large structures, adding 30% volcanic ash can reduce peak hydration temperature by 10–15°C, mitigating thermal cracking — an important consideration when designing massive components for tailings processing equipment.

1.Geopolymer precursor:
About 50% clay can be replaced by volcanic ash to produce geopolymers with compressive strength of 80–100 MPa; after 28 days in pH 2 acid, strength retention > 85%.
This makes it viable for specialized components of tailings processing equipment exposed to acid.

2.Soil stabilization and heavy metal solidification:
Through adsorption and ion exchange, Pb²+ and Cd²+ can be solidified > 90%.
Furthermore, CO₂ reacts with Ca²+ to form Calcite (CaCO₃), yielding a carbon sink of 100–200 kg per ton — valuable for tailings processing equipment in environmentally sensitive operations.

3.Functional material applications:
TiO₂-catalytic volcanic ash materials can degrade organic compounds (such as Rhodamine B > 90%) under UV, while porous lightweight aggregates made from volcanic ash have a low thermal conductivity of 0.12–0.25 W/{m.K}.
Such properties can be incorporated into specialized components of tailings processing equipment.

1.Nanomodification:
Addition of 0.1% carbon nanotubes can increase electrical conductivity by 10^4 times, which makes it useful for electromagnetic shielding and smart sensing components in tailings processing equipment.

2.Biologically-assisted activation:
Bacillus spp. secrete urease to catalyze CaCO₃ precipitation, allowing for > 60% self-repair of microcracks.
This technology shows potential for tailings processing equipment to prolong service life under mechanical stress.

The key advantage of volcanic ash materials lies in their synergy of reactivity, structure, and environmental benefits. Future research should focus on tailored modifications and low-carbon production methods.

For industrial applications — particularly in tailings processing equipment — we recommend:

1.Material selection:
Choose volcanic ash with an activity index > 70% (per GB/T 1596-2025).

2.Mix design optimization:
Use Response Surface Method (RSM) to balance mechanical and durability properties.

3.Intelligent monitoring:
Implement optical fiber sensors to track hydration progress in service.

For marine applications, high-calcium volcanic ash (CaO > 15%) is recommended to enhance chloride resistance; 3D X-CT scanning can be used to verify pore structure optimization in tailings processing equipment components.