While many concrete sealers claim to offer protection from water damage, most only offer some degree of water resistance. If you are looking for a true water repellent sealer, for instance, an acrylic will not really give you the protection you have in mind. Water repellent sealers are different from penetrating sealers because they are surface sealers. A good example to picture the protection offered by a water repellent would be that they act like a raincoat does. When applied to the concrete, the water visibly beads before sliding off, keeping the concrete dry underneath.
Just like penetrating sealers, water repellent sealers are appropriate for certain types of projects. A delicate piece of concrete cannot be treated with a concrete densifier or any other type of penetrating concrete sealer. Instead, a water repellent sealer is more appropriate, as these types of sealers feature large particles of sealant that cannot penetrate past the tiny surface pores natural to concrete. In order to ensure the concrete sealer is applied properly, you just need to pour out the sealer onto the concrete before spreading it out across the surface of the material.
If you are looking for a sealer that repels water, your best choice would be a silane/siloxane type of sealer. Be sure to look for a water-based variety that offers comparable levels of protection to solvent-based counterparts. Silane/siloxane sealers are made up of a blend of penetrating silane particles combined with surface-level siloxane particles. These two types of particles of chemical sealant function in concert to create a hydrophobic barrier that will block out water and excessive moisture from entering the concrete. The two types of sealant particles ensure that the surface of the concrete retains the most thorough possible protection, while the concrete itself is also protected in case any water seeps through the primary surface level of protection.
Our Take: Water repellents we recommend are Okon S-40 or Siloxa-Tek 8500
What are the best water repellent sealers?
If you are looking to apply a penetrating water repellent sealer we recommend choosing a silane/siloxane blend. Silane/Silixane blended concrete sealers not only penetrate concrete substrates providing concrete protection from the inside out but they chemically bond keeping water from entering the concrete. Since a Silane/Siloxane blended sealer is also a penetrating sealer driveways, sidewalks and high traffic areas will be unaffected and will not lose protection. After sealing, the concrete will stay in its natural state with no added sheen or texture. Water will be repelled and bead from the surface and concrete will be protected from water damage. Added bonuses are protection from: efflorescence, staining, spalling, scaling and deicing salts; it is considered a breathable sealer allowing water vapor to leave the slab. We recommend a Silane/Siloxane blended sealer for all concrete based surfaces especially concrete blocks, pavers, stucco, brick, clay tile, exposed aggregate, sandstone and slate. Since Silane/Siloxane sealers are blended sealers you get the benefits of two different products in one formula. Keep in mind even though they are penetrating sealers Silane/Siloxane blends are too topical in nature to be used in conjunction with a topical sealer such as an acrylic.