BRB SILOEN® 694

BRB Siloen® 694 is a reactive chemical based on octyl-trietoxysilane.
BRB Siloen® 694 is used in undiluted form as hydrophobic primer and impregnation of
concrete, reinforced concrete, autoclaved aerated concrete as well: commercial buildings,
parking decks, bridges. BRB Siloen® 694 is also suitable as hydrophobic surface modifier of
mineral fillers.

Produces a hydrophobic treatment that inhibits water absorption.
Helps dispersion of polar filler into non polar polymers (plastics, binders)

• Small molecular weight providing excellent penetration into the substrates thus preventing water and chloride absorption
• Very good water repellency on concrete and aerated concrete.
• No loss in breathability
• Provides good adhesion of the paints
• Typically used undiluted but easily dissolvable in various organic solvents, low molecular weight cyclic PDMS and alcohols whenever necessary
• Applicable to many natural fillers and different polymers

BRB Siloen® 694 will be hydrolyzed when combined with atmospheric moisture and/or with the water in the building material pores: reaction forms silanol reactive and release ethanol as by product. Silanol groups bonds to the mineral substrate while octyl functional group creates water repellent structure on the treated surface or enhances compatibility of the polar filler with non-polar organic polymers.

Sealers for Construction Materials

BRB Siloen® 694 is excellent penetrating sealer to be used mainly with construction materials such as concrete and reinforced concrete. BRB Siloen® 694 triethoxy groups reacts with moisture in the air and in the substrate in the presence of alkalis to produce hydroxyl group eliminating alcohol. Hydroxyl groups bond to the substrate whilst the alkyl chain will provide the water repellency.

Pores and capillaries are not clogged so substrate maintain its water-vapor permeability.

BRB Siloen® 694 can be applied with low airless sprayer, roller or brush; apply in almost two coats wet on wet to ensure an even coating; BRB Siloen® 694 might be also applied on damp surfaces even if dry ones are better to achieve the best penetration; in general moist content should not exceed 4%.

BRB Siloen® 694 should be applied on surfaces free of dirt, dust, oils, standing water and other contaminant; in case of soiled surfaces, clean first with steam or high pressure water being carefully to dry immediately after cleaning to prevent excessive moisture in the concrete.

BRB Siloen® 694 might be used on a fresh concrete, however is preferable to wait almost four weeks to let the concrete setting properly.

BRB Siloen® 694 is generally applies undiluted but, whenever necessary, it can be easily thinned with organic solvents e.g. mineral spirits or anhydrous (absolute) alcohols (ethanol and/or isopropanol). 20% or 40% BRB Siloen® 694 in solvent are the most typical dilution rate. Solvent can be selected in function of the required evaporation rate; preliminary test are recommended because some silane/solvent blend might darken the surface.

Mineral Filler Treatment
In the case of siliceous mineral fillers, the mineral can be treated by slurrying in the aqueous solution at 0.1-2 % BRB Siloen® 694 based on filler weight. The dosage is up to particle size or surface area of fillers which is shown in the table I. The filler treatment recommendation is mixing with the silane at very high shear (with a Waring 2 or Welex 3 blender) as a 10 percent solution in isopropanol which ratio of solution is recommended at 1:8:1 of BRB Siloen® 694: isopropanol : water.

The hydrolysis rate of BRB Siloen® 694 can be accelerated by pH adjustment. The addition of glacial acetic acid to pH 4-5 is recommended which pH 4.5 provides minimal condensation and long shelf life of solution.

After applying this silane, the mineral surface can be air-dried or dried bricfly at 104 to 121°C (220-250°F) to effect complete condensation of silanol groups at the surface and to remove water and/or traces of ethanol from hydrolysis. Optimum application and drying conditions, such as time and temperature, should be determined for each application before use in a commercial process.

Table I. Silane dosage recommendation based on particle size of mineral fillers