What's the best sealer to use on driveways to reduce scaling or to make oil stains easier to remove?
If the concrete is properly air-entrained, scaling should not be a problem. But if the concrete near the surface does not contain an adequate air-void system, scaling can occur. In these cases, ACI 332R-84, "Guide to Residential Cast-in-Place Concrete Construction" recommends applying two coats of boiled linseed oil that is thinned with an equal amount of mineral spirits, turpentine or naphtha. But Ed McGettigan, chairman of ACI Committee 515, "Protection Systems for Concrete," says that linseed oil darkens the concrete and needs to be reapplied every year or two. To reduce scaling by preventing water from entering the concrete, McGettigan recommends applying either a silane or a siloxane sealer with an active ingredient content of 10% to 20%. These sealers should provide effective water repellency for three to five years, but they will not prevent oil from soaking into the concrete. To repel oil, apply a low-solids (about 15%) acrylic or urethane sealer, which should last from two to five years. Acrylic and urethane sealers will give the concrete a glossy appearance and can make smooth concrete slippery. Concrete sealers based on aluminum stearate are available, but their low active-ingredient content makes them less effective than silanes and siloxanes or acrylics and urethanes.