Concrete, Masonry & Stone Protection

Penetrating Water Repellents for Concrete, Masonry and Natural Stone

Water is what destroys concrete. Not load, not heat — water carrying chlorides into the rebar, water freezing in capillaries and spalling the surface, water dissolving the alkalis and pushing them out as efflorescence. Penetrating silane and siloxane treatment is the cheapest insurance the construction industry has against all of that.

Manta makes the full range, from pure C8 monomer to sodium siliconate to 40% nano-emulsion cream.

Picking the right chemistry

There are three working chemistries on the market and a fourth at the high end. Pure alkyl silane monomers — C8, C12, C16, C18 — penetrate deepest, last longest, and are what most national bridge and infrastructure specs ask for by name. Water-based silane-siloxane emulsions trade some penetration depth for low VOC and easy site application; they dominate residential and most general construction. Siliconates are sodium- or potassium-based, alkaline, water-soluble and cheap, and they do most of the world’s gypsum board and mineral panel hydrophobization. At the top of the line, nano-emulsion silicone creams put 40% or more active content into a vertical-stable paste that you can roll onto a facade without it running down the wall.

Choosing wrong is expensive. C18 silane on dense concrete will sit on the surface and not penetrate. C8 silane on cultural stone will evaporate before it can bond. Sodium siliconate on a poured concrete bridge deck will fail in two years. The substrate, the porosity and the exposure decide the chemistry — not price.

What Manta supplies

• Pure alkyl silane monomers— C8, C12, C16, C18, neat
• Silane-siloxane emulsions— 40–60% active, water-based
• Siliconates— sodium and potassium, liquid and powder
• Silicone creams— 40%+ nano-emulsion paste for vertical surfaces
• Coating-stable additives— for in-paint and in-render hydrophobicity
• Silicone resin emulsions— for breathable mineral facade paint

Recommended Manta products

Why C8 (Manta L320) is the global infrastructure standard

Carbon chain length sets penetration depth. Short C4 silane is too volatile — it flashes off the surface before it can hydrolyze. Long C16 and C18 silanes are stable but their molecules are too bulky to migrate into dense concrete capillaries; they bond well on the top millimeter and stop. C8 sits in the middle. It penetrates 4–8 mm into typical bridge-deck concrete, hydrolyzes cleanly with ethanol byproduct rather than methanol (a real safety advantage on site), and forms a covalent siloxane network that is stable in the alkaline environment of fresh concrete.

This is why every major infrastructure spec — US DOT, German ZTV-ING, UK Highways, China JT/T 535 — calls out C8 or 40% C8 emulsion as the default. Manta L320 is produced as 100% n-octyltriethoxysilane to industrial grade, with COA on every drum.

For premium natural stone where staining is unacceptable, C12 (Manta L1231 or L1232) is the safer choice. The longer chain has lower volatility and a more controlled penetration depth — the stone takes the treatment without darkening, which matters on light-colored marble and limestone.

Cross-reference to industry standards

• Manta L320 — comparable to Momentive Silquest® A-137, Dow OFS-6341, Evonik Dynasylan® OCTEO, Wacker GENIOSIL® OCTEO, Shin-Etsu KBE-3083
• Manta L1231 — comparable to Wacker GENIOSIL® DD-Trimethoxy
• Manta WS100 — comparable to Wacker SILRES® BS 1701 and BS 1306
• Manta WS120 — comparable to Wacker SILRES® BS Creme C and Evonik Protectosil® CIT
• Manta MSEP / MSES — comparable to Evonik Protectosil® WS 405 and Wacker SILRES® BS 16

All trademarks belong to their respective owners. Cross-references are provided for technical comparison only.

FAQ

How long does silane water repellent last on concrete?

For C8 silane (Manta L320) properly applied at 250–400 g/m² on quality concrete, 10–15 years of effective hydrophobicity is the realistic field expectation, validated against EN 1504-2 and ASTM C1583. Re-treatment on heavy-traffic bridge decks usually comes around year 12.

Can I dilute Manta L320 with water?

No. Pure alkyl silane is not water-soluble — it requires organic solvent dilution (ethanol, isopropanol, mineral spirits) at typical 4–10% active content for site application. If you want a water-based product, choose Manta WS100 series instead.

Siliconate or silane-siloxane emulsion?

Siliconate is alkaline, water-soluble and inexpensive. It works well on porous gypsum board, mineral wool, autoclaved aerated concrete. It does not work well on dense exposed concrete or weathered masonry — the alkaline carrier reacts with CO₂ over time and the treatment fails. For dense concrete, brick and stone exposed to weather, silane-siloxane emulsion is the correct chemistry.