85% Densified Silica Fume

1️⃣Product Overview

85D Silica Fume is a densified microsilica product with a silica (SiO₂) content of no less than 85%. It is an amorphous, powdered silica collected by specially designed dust collectors from the fumes produced during the smelting of ferrosilicon or industrial silicon, where silicon vapor oxidizes. It consists of ultrafine spherical particles with an average particle size of 0.1-0.20 μm and a very high specific surface area of 15,000-20,000 m²/kg, giving it extremely strong surface activity. The "D" indicates that it has undergone a densification process, resulting in higher bulk density for easier handling and transportation.

2️⃣Key Performance Characteristics

· Substantial Strength Enhancement: Possessing high pozzolanic activity, it significantly increases the compressive, flexural, and tensile strength of concrete.

· Enhanced Density & Impermeability: The ultra-fine particles effectively fill voids between cement particles, resulting in a denser matrix with reduced porosity. This greatly improves impermeability.

· Superior Durability: The dense structure effectively impedes the penetration of harmful substances like sulfates and chloride ions, enhancing resistance to chemical attack and abrasion.

· Improved Refractory Properties: In refractories, it increases bulk density, reduces porosity, and enhances strength, while also improving high-temperature strength and thermal shock resistance.

3️⃣Application Fields

· High-Performance Concrete: Used in high-grade (C70 and above) concrete, high impermeability (≥P30) structural concrete, and concrete for marine and chemical environments requiring corrosion resistance.

· Transportation & Hydraulic Engineering: Applied in bridges, highways, dams, and other structures demanding high abrasion and erosion resistance.

· Refractory Materials: Serves as an additive in high-performance castables, precast shapes, etc., improving flowability, density, and strength.

· Other Fields: Also used as a functional filler in industries like cement, rubber, and coatings.

4️⃣Usage Guidelines

· Mandatory Use with Superplasticizers: Due to its fine particles and high surface area, which increase water demand, silica fume must be used in combination with high-range water reducers to achieve optimal results.

· Optimum Dosage Control: The dosage in concrete should be carefully controlled, typically recommended at 5% to 10% of the total cementitious material weight. Within this range, its beneficial effects are maximized.

· Extended Mixing Time: The mixing time for silica fume concrete should be extended by 0.5 to 2 minutes compared to ordinary concrete to ensure uniform dispersion and prevent balling.

· Enhanced Curing Regime: Prompt and diligent moist curing is essential. It is advised to start moist curing 2-4 hours after final setting and maintain it in a moist environment for at least 14 days.

5️⃣Packaging & Storage

· Packaging: Usually supplied in sealed, plastic-lined woven bags, with common sizes being 25kg/bag or jumbo bags (e.g., 500kg, 600kg).

· Storage Conditions: Store in a cool, dry, and well-ventilated warehouse. Must be kept dry and protected from moisture.

· Shelf Life: Typically 24 months under proper storage conditions.