Characteristics of a good concrete driveway sealer include breathability, durability, a nonslip finish, environmentally safe and easy application. Concrete is extremely porous, which allows water to seep into it. Poor concrete driveway sealers only seal over the top of the concrete, which traps the water.
Trapped water causes concrete to deteriorate much more rapidly. A good concrete sealer seals the concrete all the way through and still allows water to evaporate.
Another characteristic of poor quality concrete driveway sealant is susceptibility to ultraviolet rays. Acrylic, siloxane-based, polyurethane and epoxy sealers break down considerably when exposed to ultraviolet rays from the sun over long periods of time. These types of sealers need to be reapplied regularly. A good sealer is permanent and does not need to be reapplied regularly to preserve the concrete.
Acrylic sealers work by forming a thin layer over the surface of the concrete. Not only does this not allow water to escape from the concrete, but it also causes the surface of the concrete to grow slippery while it is wet or as the sealant is worn away. This can be avoided by using a good concrete sealer that penetrates deeply into the concrete and does not leave a layer of film on the top of it.