85% Densified Silica Fume (Microsilica) | SF-85D

The main advantage is cost efficiency for applications that do not require a higher-purity grade. Where the project specification allows silica fume with a minimum SiO₂ content of 85%, SF-85D can provide the microfiller and pozzolanic effects required for many general concrete and infrastructure applications while offering a more economical raw-material option. Higher-purity grades may be more appropriate where greater reactivity, tighter impurity control, specialized formulations, or specific project standards are required. Grade selection should therefore be based on the actual performance target rather than SiO₂ content alone.

The primary advantages are easier handling and improved logistics. Undensified silica fume has a very low bulk density and therefore occupies considerably more storage and transportation volume. Densification increases the bulk density to approximately 450–700 kg/m³, allowing more material to be transported and stored within the same volume. The densified form also generates less airborne dust during handling and is generally better suited to automated batching and large-scale concrete production. Undensified silica fume, however, may provide easier dispersion in certain fine-particle systems. The appropriate form should be selected according to the customer’s mixing equipment and application.

Yes, provided that suitable mixing equipment and procedures are used. Densified silica fume consists of soft agglomerates rather than permanently fused particles. In concrete containing coarse and fine aggregate, mechanical shear and aggregate-to-aggregate friction help break down these agglomerates during mixing. Twin-shaft, planetary, and other sufficiently intensive mixers generally provide favorable dispersion conditions. Proper feeding sequence and adequate mixing time remain important, particularly when high silica fume dosages are used.

SF-85D is primarily intended for concrete applications where coarse aggregate and mechanical mixing provide suitable dispersion conditions. Typical applications include: Ready-mix concrete Infrastructure and structural concrete Bridge and road construction Underground concrete structures Marine and hydraulic structures Industrial foundations Precast concrete components Large-volume concrete projects For highly specialized concrete systems or applications requiring tighter chemical specifications, a higher-purity silica fume grade may be more appropriate.

A typical starting range is approximately 5–10% of the cementitious material by mass, but there is no universal dosage suitable for every concrete formulation. The optimum dosage depends on target strength, permeability requirements, water-to-binder ratio, cement type, aggregate grading, admixture system, and curing conditions. Laboratory mix trials should be carried out before commercial production. Because silica fume increases the surface area of the binder system, an appropriate high-range water-reducing admixture is commonly used to maintain the required workability.

The effect on total cost depends on the mix design and project requirements. Silica fume has a higher unit cost than ordinary Portland cement, but its value should be evaluated based on the complete concrete formulation rather than material price alone. Where silica fume helps achieve required strength, permeability, durability, or binder-efficiency targets, the overall mix can often be optimized accordingly. The densified form can also reduce transportation, storage, and handling costs compared with undensified silica fume. For large projects, we recommend evaluating both cost per ton and cost per cubic meter of finished concrete.