What is concrete sealer?
A concrete sealer is a product, method or particular system of treatments to a concrete surface designed to seal a concrete, thus preventing any movement of atmospheres or contaminants from entering or migrating out of a concrete material.
Sealers may accomplish this in two basic ways. A Barrier Coating is the most common. As the name implies, a product is applied to a concrete surface that forms a film and a barrier to prevent entry to the concrete via a Gel=Pore or Capillary system. A Penetrating Sealer is a product designed to enter the concrete matrix by penetrating into the Gel-Pore / Capillary system. As a basic premise to concrete in general, it needs to be understood that water in the initial placement of concrete is required to mix with or Hydrate the Portland cement product found in all concrete structures. This water used to initiate hydration escapes to a surface and evaporates. As this occurs microscopic paths allow this water to come to a surface forming a path of tunnels inside the concrete that create a honeycomb like system that becomes a void in the concrete. A small amount of water put on a concrete surface will be absorbed into the material demonstrating that the surface is porous and capable of absorption of not only water, but also gases or vapors that move into and out of a concrete.
A barrier or coating placed on a surface hopes to prevent moisture or gases from being able to penetrate a concrete. These coatings have a limited life cycle because they will fail and become ineffective when moisture vapor within the concrete carries moisture and chemicals out of the concrete to collect at the concrete / coating interface. This usually causes a bond failure, blistering or collection of moisture vapor underneath a barrier system. Paints are an example of a barrier coating that frequently bubble, burn or blister off a surface in a short time period!
A penetrating sealer is designed to fill these Microscopic voids stopping any further movement of moisture or vapors in or out of the matrix. They are by far the most effective choice of a sealer because they do not change a surface profile, nor are they prone to degradation by the Alkali found in cement products.
When choosing a penetrating sealer, care should be taken to read and understand any warranty or cautionary statements printed on the container or in literature associated with the product. If a product provides for additional applications at some later date; ask what happened to the first application? If a product warns to avoid exposing this product to metal or glass surfaces because it will etch these materials; this denotes a Sodium Silicate chemistry with a very short life span! Also be aware that a number of purported sealers have issues with adhesion of coatings once they have been applied. Always read the technical data or MSDS sheets and be very careful to use a low or no VOC content product when contemplating use in a close or confined interior space.
Concrete Sealers are very important in the preservation of a concrete and should be chosen based on the factors discussed above and the service conditions the concrete material will be exposed to during it’s life cycle. Contact an experienced person before making a costly mistake!
Concrete sealer is a compound which is used to protect concrete from the elements. Concrete is a porous material, and without sealing, it will freely breathe. It will also suck up water, which can lead to a variety of structural and aesthetic problems. Many home supply stores carry concrete sealers for people working on projects at home, and it is also possible to purchase sealers through contracting suppliers and specialty companies. Concrete should not be left unsealed, except in certain circumstances.
