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  • Overview
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  • Application

Aerosil R 202 Fumed Silica Thickening Agent | Evonik 

Aerosil R 202 Fumed Silica Thickener is used in concrete repairs with epoxy systems and polyester resins as a thickening and thixotropic agent to create a smooth, non-sagging, high-strength mixture for structural bonding, filleting, and filling. It’s best to use Fumed Silica when high-strength and easy to to apply low-density are required. Aerosil R 202 Fumed Silica is a hydrophobic grade and is great to mix with composites, coatings, adhesives and sealants, especially epoxy and polyurethane systems for bulking up for various uses including use in crack and joint repairs.  The Aerosil R 202 brand Fumed Silica is the original, made by Evonik Industries.

For DIY homeowner and smaller repair projects, see our ready-to-use HyperCURE Concrete Repair Kit.  HyperCURE is easy to use and offers minimal waste.

Aerosil R 202 Fumed Silica comes in a 22 lb container (minimum order 5 bags shipped LTL Freight when just ordering Fumed Silica) and is meant for larger concrete repairs.  A 5 quart quantity of Aerosil R 202 Fumed Silica Thickener when combined with 1 gallon of mixed epoxy/hardener, will produce about 1.75 gallons of smooth, thixotropic epoxy joint and crack filler.  You can use more or less Fumed Silica depending on how thick you want the gel to become.  Suggest using mask when mixing Fumed Silica as it is composed of very fine particles.

Recommend mixing the Aerosil R 202 Fumed Silica with HyperFLEX Epoxy which offers an exceptionally quick 15-30 minute recoat time.  Apply coatings over your repair up to 24 hours after your repair without any special preparation.  After 24 hours requires sanding 100 grit sander then wipe down with acetone solvent and when flash dry, can apply new coating over the repaired area.

 Where is Aerosil R 202Fumed Silica Used in Concrete Repair Projects?

  • Concrete Cracks, holes, spalls and control joints
  • Concrete Thresholds
  • Uneven Concrete Slabs
  • Garage floors
  • Warehouse floors
  • Freezer floor projects
  • Other applications include:
    • Composites & Molding
    • Industrial, Marine & Protective Coatings
    • Pulp, Paper & Printing Processes
    • Rheology Control
    • Silane Modified Polymers (GENIOSIL)
    • Structural Bonding of Wind Turbines
    • Wind Energy

Why Aerosil R 202 Fumed Silica?

  • Great thickening agent to wide range of coatings including epoxy and polyurethane coatings
  • Allows coatings to be used as great concrete crack, hole, joint and spall repairs
  • When mixed into fast cure epoxy, makes for very quick repairs


Specific Surface Are (BET) 80-120 m²/g   DIN ISO 9277 DIN 66132
pH Value in 4% dispersion 4.0-6.0   DIN EN ISO 787-9
SiO₂-Content (based on ignited material) > 99.8 %   DIN EN ISO 3262-19
Loss on drying (2 hours at 105C) < 0.5 %   DIN EN ISO 787-2
Appearance Fluffy white powder
Tamped density approx. 60 g/l   DIN EN ISO 787-11
Carbon content 3.5 – 5.0 %    DIN ISO 10694



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