Concrete sealants: Simple solutions for heavy-duty projects

Reach for your concrete sealant if you need to fix cracks in sidewalks, walls, floors, or other concrete surfaces. While some of these occurrences are simply unsightly, others, like gaps in sidewalks, can be dangerous and need to be repaired quickly. If your next DIY project involves sealing a concrete joint or crack, read on for tips on selecting and applying the proper concrete sealant to a range of materials.

Generally speaking, you can use sealants for concrete to repair or protect concrete surfaces.

If you have a repair project at hand, you will want to use a flexible filling material to repair driveways, garage floors, concrete floors and decks, and sidewalks. If you think the name is the game, you might be surprised to learn that some concrete sealants can repair other materials besides concrete. Some even work for bonding materials to brick, stucco, metal, wood, vinyl, fiberglass, and other substrates.

While this guide focuses on repairs, it is worth noting that you can seal entire surfaces like concrete floors to protect them and make them easier to clean.

While this guide focuses on repairs, it is worth noting that you can seal entire surfaces like concrete floors to protect them and make them easier to clean.

1. Clean the surface of all dirt and debris, including unsightly stains on the area you want to seal, and remove any substances like oil, grease, wax, and mastic compounds. If you use a fluid cleaner, let the area dry before you apply the sealant. It is a good idea to use a stiff, high-density back-up material or backer rod for joints that can easily be punctured—for instance, in areas where stilettos are worn.
2. Wear gloves to protect your skin; the sealant may cause temporary stains.
3. Check for temperature restrictions for your product and make sure you can apply it under the planned conditions.
4. Cut the nozzle to the desired bead size at a 45-degree angle and puncture the inner seal.
5. Test one joint or area before applying the concrete sealant to your entire project to make sure you get the results you want.
6. Prime the surface if your sealant requires primer. Let the primer dry before applying the sealant. Depending on the ambient conditions, your primer will be ready for sealant after 15 to 30 minutes. Make sure to prime and seal on the same day.
7. Apply your sealant with a steady pressure, forcing it into the joint in the proper direction – check the manufacturer’s instructions to find out if you need to fill joints from the bottom and when to perform dry tooling, if required. The instructions are generally valuable sources of information; even within the same product family, sealants may have different cure times, for instance.
8. Clean your tools and any uncured sealant residue immediately upon completion of your project, using mineral spirits. If necessary, do this in a well-ventilated area that opens up to the outdoors. You can carefully cut away cured sealant with a sharp-edged tool.

Concrete sealants are designed to be tough and should be able to withstand various conditions. But over time, concrete sealants can slowly deteriorate especially if used on entire surfaces like driveways or walkways. Before applying a fresh coat of concrete sealant, you must properly remove it first.

1. Identify the type of concrete sealant used. Sealants for concrete can either be solvent or water-based. If you are unable to remember what type of concrete sealant was used, you can pour a small amount of Xylene, a strong solvent, on the surface with the sealant. Let it sit for a few seconds then rub it with a cloth. If the concrete sealer is solvent-based, it will have a sticky texture while a water-based sealer will have a smooth surface.
2. Choose the right removal method: mechanical or chemical. Depending on the outcome of the first step, the right removal of concrete sealant can either be mechanical or chemical.
   
   Mechanical is best for removing water-based concrete sealants. You can use either power washing or pressure washing. Sandblasting would work as well but you will need assistance from a professional to do so.
   
   Chemical strippers for removing solvent-based concrete sealers have three types: solvent-based, caustic, and biochemical. If you are in a hurry, solvent-based strippers are your best option but be careful when using them as they can be harmful to the skin. Caustic strippers are less harmful but they are not effective on some surfaces like epoxy and acrylic. Lastly, biochemical strippers are eco-friendlier and easier to use but they can take more time to react to concrete sealers.
   
   Regardless of what you choose, always follow the manufacturer’s directions and safety guidelines. Each type of product needs to be handled with care. Always have the proper safety equipment to avoid harming yourself, and others, and avoid chemical reactions.
3. Rinse and dry. Once you have fully removed the concrete sealant from the surface, do another rinse with water using a pressure washer to remove any leftover residue. Dry the surface for 24 to 48 hours. Once completely dry, you can now start resealing again and it will be good as new.

Not all sealants are suitable for all projects. There is a range of products that will make your project a success, whether you use them as concrete joint caulk or sealants for concrete.

Foundation, walls, and masonry. If you need to repair concrete, brick, stone, or masonry, you will need a product that forms permanent waterproof and weatherproof seals for all kinds of exterior gaps and joints and that can withstand harsh environments. Find something that is suitable for repairing cracks in vertical and horizontal surfaces and bonds to concrete, brick, stucco, metal, wood, vinyl, fiberglass, and other substrates. Make sure your concrete is fully cured before applying a sealant. Check the manufacturer’s directions before choosing a product or seek professional advice to avoid serious structural concerns for your project.

Driveways, sidewalks, floors, and decks. These surfaces are exposed to pedestrian and vehicular traffic, so your sealant will need to resist abrasion and tear. Additionally, if you are sealing contraction/expansion joints on these surfaces, you will need a sealant that forms flexible bonds that withstand joint movement without distortion or failure just like LePage PL Polyurethane Concrete Crack & Masonry Sealant. Again, make sure that the concrete is fully cured before you start sealing.