Concrete sealers: Protecting your hard assets  ( 8/1/2012 )
By  Paula Mayfield , IMI Concrete, Evansville, Indiana

One of the best ways to preserve your concrete, especially concrete that is exposed to the elements, is to seal it. There are several different kinds of sealers based on the type and age of your concrete. Most options are easy to apply and do not require any special equipment, just a few basic guidelines.

The point of using a concrete sealer is to keep water and other contaminants from penetrating into the concrete. Does water penetration damage concrete? Not necessarily, but if the water is mixed with dissolved chemicals or minerals, such as fertilizers or road salts, these can eat into the concrete and cause it to pit, crack or crumble. Water inside the concrete slab can also become a problem in freeze and thaw cycles and cause the concrete to crack with the expansion of the water as it freezes. Sealers help prevent this from happening.

Prepping your concrete
If you are sealing old concrete, pick a time when no rain is in the forecast for at least 72 hours. Make sure you properly clean the surface before you seal it. That would include using a mild detergent with agitation, followed by pressure washing any dirt or debris from the surface including the concrete joints. After this, remove any standing water, including any water in the concrete joints and cracks. In some cases a blower or broom is needed to remove excess water. Allow your concrete to dry for 48-72 hours before you apply the sealer. Applying a sealer before the moisture has evaporated can lead to trapped water just below the surface that can cause the sealer to fail to bond, become cloudy from moisture accumulations, or cause the life of the sealer to be shortened due to poor curing.

Applying sealers
Based on the type of sealer you select, a pressure sprayer (cone shape/.5-1" gpm tip) or a nap roller on an extension pole may be used. Some specialty sealers may require agitation with removal of excess product or recommend squeegee application followed by buffing. Check the recommended application method and coverage rate on the product’s label. As you are applying it, make sure you overlap your strokes 1-3 inches. Work on an area that is small enough that the last stroke is not drying out before you apply the next stroke. Do not stop until then entire section is completed. Let the area dry for 24 hours before allowing traffic back on the concrete. In temperatures of 40-70 degrees F, allow 48 hours of curing time before you allow traffic back on the concrete.

Things to consider
Sealers are made specifically for the age and the application of the concrete. For instance, if you are sealing new concrete in a pole barn where you are doing a lot of maintenance work, you may want to use a densifying sealer. This is a permanent sealer that chemically changes and hardens the surface of the concrete, creating crystals that help fill the pores in the concrete. This slows the rate that grease and oil are absorbed. This extra time allows you time to clean up spills before staining occurs. This type of sealer will also continue to harden with abrasion, so the crystals actually continue to expand with use of the concrete. This further slows the absorption rate. If you are sealing concrete that is exposed to the elements, such as the floor of a grain bin or a concrete block wall, you should consider a water-based siloxane sealer. These are deep penetrating sealers that need only be applied every 3-5 years in low traffic areas. They do not change the appearance of the concrete and create a barrier to water and salt absorption. If you are dealing with concrete that is older than 180 days, and are concerned about preserving the beauty of the concrete (for instance, where you have decorative or colored concrete), you will want to consider a water-based or solvent-based acrylic sealer. These sealers darken the color of the concrete. They leave a decorative film that accentuates color and texture. They also restore the new, wet and clean appearance of the concrete. There are special color tinted sealers that enhance colored or decorative concrete, such as brown tint for an exposed aggregate finish. Other sealers are completely clear with finishes differing from high gloss to matte.

One thing to consider with any sealer is the amount of fumes they produce. Solvent sealers are regulated by their Volatile Organic Compounds (VOC) rating. A VOC rating dictates how long the vapor from the solvent remains in the atmosphere. Certain states, including Indiana, Illinois, Ohio have VOC restrictions in place to reduce ozone depletion. However, there are other concerns with these fumes beyond environmental worries. High VOC fumes can be harmful if they are inhaled by the applicator. For this reason, you want to consider where the concrete is located before you choose a sealer. If you are sealing an area that is inside an enclosed building or has poor ventilation, you need to use a water-based sealer. Acrylic-based sealers in compliance with low VOC require a respirator mask covering the mouth, nose and eyes for the applicator and are extremely flammable. Solvent-based sealers with high VOC can also be hazardous if no ventilation is present, but do not require a respirator if they are used outdoors. Follow the safety cautions on the label of the sealer you are using.

IMI stocks sealers at our concrete plants. For more information on sealers available in your area, click here.