Typically used in the exterior applications, penetrating concrete sealers actually "penetrate" into the concrete and form a chemical barrier which protects against water, deicing agents as well as moisture. Penetrating concrete sealers usually leave a "natural finish" and do not change the appearance of the surface, most of the penetrating sealers are "breathable" not sealing the concrete which allows vapors to escape. Penetrating concrete sealers are typically used for driveways as most of the sealers have a long lifespan and only require reapplication every 4 to 5 years or so.
Four application of a penetrating concrete sealer, it is quite simple and most "do-it-yourselfers" can seal their driveway or whatever other concrete feature by simply using a sprayer and roller. Once the penetrating sealer is applied its main job is to reduce the substrate's ability to take on water. Imagine this, imagine your concrete driveway is like a sponge with open cavities going all the way to the substrate or the soils beneath concrete. Without a sealer of some kind blocking the cavities, water can absorb from the top of the driveway all the way through the concrete pad and to the bottom of the driveway which then is absorbed by the substrate beneath. Having water buildup between the driveway and the substrate can cause stains on the top of the driveway and create moisture erosion in that area.
Applying a penetrating sealer typically does not require much preparation on the surface of the concrete other than cleaning the surface and having it completely free of any other curing agents, topical coatings, dirt, dust, grease, oil or other previous sealants that were applied. Perhaps the best way to clean the surface that you will be resealing or sealing for the first time is to use a pressure washer and diligently clean the surface.
A penetrating concrete sealer will stop the flow of moisture or water from the top of the concrete pad through the bottom of the pad. It's important to know that the sealer is not completely comprehensive meaning that it does not completely seal the concrete as it does allow vapor and gas to move through the concrete still.
There are five different types of penetrating sealers in the marketplace, these are:
Each of these different sealers are used for different reasons. The silicates are classified as hardener's or "densifiers". Silanes, Silisconates and siloxanes are all used as water repellents in concrete while Fluorinated materials are used to repel oil and water.
When applying a penetrating concrete sealer, after the surface has been cleaned there is no need to profile the surface by grinding, shot blasting, sandblasting, scarifying a surface or acid etching, the surface should be dry so as to allow the sealant to be absorbed completely by the concrete.