Concrete is an incredibly stable and durable material. While versions of cement are millennia old, modern hydraulic concrete was first created in 1756. Concrete buildings, bridges, and other surfaces that are hundreds of years old are still standing today.
But concrete is not indestructible. Naturally occurring cracks, and those caused by poor design, do happen. Luckily, the best concrete crack fillers can repair those cracks in foundations, driveways, walkways, sidewalks, patios, and more, making them virtually disappear. Keep reading to learn more about repairing these unsightly situations and some of the best concrete crack fillers on the market to do the job.
- BEST OVERALL: Sikaflex Self-Leveling Sealant
- BEST BANG FOR THE BUCK: Sashco 16210 Slab Concrete Crack Repair Sealant
- BEST FOR FOUNDATIONS: RadonSeal Concrete Foundation Crack Repair Kit
- BEST FOR LARGE CRACKS: Red Devil 0644 Pre-Mixed Concrete Patch
- BEST FOR THIN CRACKS: Bluestar Flexible Concrete Crack Filler
- BEST SEALANT: Dap 18370 Self-Leveling Concrete 3.0 Sealant
- BEST CURE TIME: DRYLOK 00917 Cement Hydraulic WTRPRF
- BEST EPOXY: PC Products 72561 PC-Concrete Two-Part Epoxy
- ALSO CONSIDER: Damtite 04072 Concrete Super Patch Repair
What to Consider When Choosing the Best Concrete Crack Filler
Concrete cracks happen for various reasons. Sometimes a natural shift in the ground from a freeze-thaw cycle is to blame. Cracks can also occur if concrete was mixed with too much water or allowed to cure too quickly. Whatever the case may be, there’s a quality product for patching those cracks. Here are the factors and features to keep in mind as you shop.
Concrete crack fillers come in a few varieties, and some are better for a particular type of repair than others.
- Concrete crack sealants and caulks are the most common product used to fill cracks in concrete. They come in squeeze tubes and can be applied right into the crack with a caulking gun. Both do a good job of keeping out water and bugs. The main difference? Caulks tend to dry faster, while sealers tend to last longer.
- Quick-setting cement, just as it sounds, is a concrete mix that sets fast. Most often, these products come as a bag of dry mix that the user blends with water. They’re excellent for fixing large cracks.
- Patching compounds are an attractive alternative to quick-setting cements as they tend to come premixed. They’re also a good choice for repairing larger cracks.
- Hydraulic cement is a dry mix (sometimes available as a premix) that users can apply to cracks in areas frequently exposed to water, such as pools, foundations, cisterns, and outdoor fountains.
- Concrete resurfacer is a relatively standard mix of concrete plus additional polymers. These polymers increase the strength of the concrete and make it suitable for applying in thin applications. They’re ideal for fixing several cracks in a surface.
- Epoxy resurfacers, a combination of a resin and a hardener, are entirely waterproof and can be useful for sealing off cracks in basement and foundation walls as well as horizontal surfaces. But you’ve got to work fast, as epoxy resurfacers harden very quickly.
The width of the crack is a major consideration when choosing a concrete crack filler. Thin cracks need a different approach and material than a thicker, wider crack.
For hairline cracks, choose a liquid sealer or thin caulk, which can flow easily into the crack and fill it. For medium-size cracks (about ¼ to ½ inch), a thicker filler, such as a heavier caulk or patching compound, might be necessary.
For larger cracks, quick-setting concrete or a patching compound might be the best bet. A standard concrete mix might also do the job, and you can mix as much as you need to fill the crack. Finishing with a resurfacer can help hide the repair and add more strength.
All concrete crack fillers should be weather resistant and able to keep water out. Penetrating water can degrade the quality of concrete over time, causing it to crack and crumble. Sealers are especially good for this purpose, as they fill the crack and reduce the porosity of surrounding concrete.
Northerners take note: Keeping water out is particularly important in colder climates. When water penetrates a concrete surface and the temperature drops below zero, ice forms—and expands. This can cause massive cracks, foundation failures, and crumbling walls. Frozen water can even push concrete blocks right out of their mortar.
Each product has its own curing time, which is essentially the time it takes to dry fully and be ready for traffic. Some materials also have set times, which means it’s not quite dry but won’t move or run, and might even survive light rain.
Though manufacturers don’t typically indicate set or cure times in product descriptions, most quality products will set within the hour and cure within a few hours. If a product requires mixing with water, the amount of water used will have some bearing on cure time.
Before beginning a repair, consider the weather and temperature. The material will dry faster in warmer weather—but if using concrete mix, you don’t want it to dry too quickly or it will crack again. So you might need to keep the surface of larger patched cracks damp in hot weather.
Many, but not all, liquid caulks, sealers, and patches come premixed. Dry mixes require water, followed by hand mixing until they reach the desired consistency—which could be a combination of the manufacturer’s recommendations and how runny you need it to be. It’s best to follow mixing directions as closely as possible, but you can thin the mix with a minimal amount of extra water if absolutely necessary.
In the case of an epoxy, users will mix a resin compound with a hardener. Luckily, most concrete epoxies come in tubes with self-mixing nozzles. Just be aware that these products become very hard very quickly, so you’ll have a limited amount of time to tackle the job. They’re common in foundation repair kits, as they can be applied on vertical surfaces and block groundwater from seeping through.
There are a few different methods for applying the best concrete crack fillers, and the one you choose will depend on the product and the size of the crack.
Liquid fillers come in small jars, and they’re easy to drip right into the crack. Caulks and sealers may be applied with a caulking gun for small to medium-size cracks. Many of these products are self-leveling as well, which means users shouldn’t have to smooth them out to ensure a uniform finish.
If going with a concrete mix or patch (dry or premixed) for larger cracks, it’s usually best to apply with a trowel or putty knife, pushing the material into the crack and smoothing it off at the surface. Resurfacers might require a float (a flat, wide tool meant to flatten masonry materials) to apply a smooth, even coat.
Our Top Picks
The best concrete crack fillers can make an unsightly crack a distant memory in one afternoon. The following products are considered among the best on the market, but be sure to keep the above considerations in mind while deciding on the best one for your projects.
Whether it’s a small crack or a wide gap, Sikaflex Self-Leveling Sealant is up to the task. This product can fill gaps up to 1½ inches wide on such horizontal surfaces as floors, walkways, and patios with ease. Once fully cured, it remains flexible as well as entirely submersible, making it suitable for pool repairs or other areas exposed to water.
Sikaflex comes in 10-ounce containers that fit standard caulking guns. Simply squeeze the product into the crack and, thanks to its self-leveling quality, little to no tool work will be necessary for a uniform finish. Fully cured Sikaflex can be painted, stained, or sanded to the user’s desired finish.
Budget-friendly Sashco’s Slab Concrete Crack Repair is all about flexibility, stretching up to three times the width of the cracks it repairs. This sealant can handle cracks up to 3 inches wide on sidewalks, patios, driveways, floors, and other horizontal concrete surfaces.
This 10-ounce tube of sealant fits in a standard caulking gun and flows easily, allowing users to squeeze it into small or large cracks without trowels or putty knives. Once cured, it remains elastic and flexible, preventing further damage from freeze-thaw cycles. This product is also paintable, so users can blend the repair joint with the rest of their concrete surface.
Filling concrete cracks in foundations often takes a specially designed product—and RadonSeal is a wise choice to get the job done. This repair kit uses epoxy and polyurethane foam to fix cracks up to ½-inch thick in basement foundations and concrete walls.
This kit includes two tubes of polyurethane foam for filling the crack, injection ports for adhering over the crack, and two-part epoxy for sealing the crack before injecting. There’s enough material to fill cracks up to 10 linear feet long. The repair will prevent water, insects, and soil gases from penetrating the foundation, keeping homes safer and drier.
When dealing with a large crack in concrete or a missing chunk of masonry material, repair might require a substantial product like Red Devil’s 0644 Pre-Mixed Concrete Patch. This product comes in a 1-quart tub and it’s premixed and ready for use.
Red Devil Pre-Mixed Concrete Patch is suitable for large cracks in sidewalks, walkways, and patios, as well as vertical surfaces both indoors and out. Application simply requires the user to push it into the crack with a putty knife and smooth it along the surface. Red Devil adheres well, dries to a light concrete color, and won’t shrink or crack, resulting in a long-lasting fix.
Hairline cracks can be challenging, and they require a thinner liquid material to penetrate and seal off the gap. Bluestar’s Flexible Concrete Crack Filler’s liquid formula seeps into those skinny cracks to create a long-lasting repair that remains flexible in hot and cold weather.
This 1-pound bottle of concrete crack filler is easy to apply: Simply remove the cap on the nozzle and squeeze the liquid over the crack before troweling it smooth with a putty knife. After it cures, users can paint it to match the concrete surfaces and rest assured that the repair will keep bugs, grass, and water from penetrating.
Dap’s Self-Leveling Concrete Sealant is worth checking out to make a quick, permanent repair in a horizontal concrete surface crack. This tube of sealant fits a standard caulking gun, squeezes into cracks easily, and will self-level to create a smooth, uniform repair.
The sealant will be waterproof and weatherproof in 3 hours, and users can paint over it in just 1 hour, quickly repairing cracks in horizontal masonry surfaces. This formula is also designed to be mold and mildew resistant, making it a good choice for areas that see consistent moisture.
When time is of the essence, Drylok’s 00917 Cement Hydraulic WTRPRF dry mix is worth consideration. This mix sets within 5 minutes, making it suitable for patches in a variety of masonry surfaces.
This hydraulic cement mix comes in a 4-pound tub and works to repair cracks in masonry, brick walls, and concrete surfaces. It can also anchor metal, such as brick ties, to a concrete surface for a long-lasting repair. Once cured, the resulting material is extremely hard and durable, capable of blocking out soil gases and holding back over 3,000 pounds of water from flowing through a crack or hole.
It can be difficult to find a product that’s both strong and fast curing, but PC Products PC-Concrete Two-Part Epoxy checks both boxes. This two-part epoxy can fix cracks or anchor metal like lag bolts and other hardware into concrete, creating three times the strength of the concrete it adheres to. And, with a 20-minute set time and a 4-hour curing time, it’s ready for heavy lifting quickly.
This two-part epoxy comes in an 8.6-ounce tube that fits into a standard caulking gun. An innovative mixing nozzle frees users from worry about mixing the two parts correctly. The cured epoxy is waterproof and fully submersible, and it works on sidewalks, driveways, basement walls, foundations, and other concrete surfaces.
Filling large cracks, deep depressions, or areas with missing material can be tough with a caulk or liquid. Fortunately, Damtite’s Concrete Super Patch Repair can remedy all those big issues and more. This waterproof patching compound uses a unique nonshrink formula that can be applied to concrete surfaces in 1-inch thick layers, up to 3 inches thick.
This patch kit comes with 6 pounds of patching powder and 1 pint of liquid additive, so users can mix as much or as little as needed to patch or resurface concrete surfaces. For reference, one of these containers will cover up to 3 square feet of patio, driveway, or other concrete surfaces in a layer ¼-inch thick. Users will have to trowel it into the crack or over a cracked surface.
FAQs About Concrete Crack Fillers
Though you’re now armed with ample info on the best concrete crack fillers, some more questions might pop up. Check for the answers to your question below.
Q. How do you fill large cracks in concrete?
Filling large cracks usually requires a thicker compound like concrete or a patching compound.
- Clean the crack with a brush and vacuum, or blow any dust out of the crack.
- Using a trowel, push the mix into the crack.
- Trowel over the compound to smooth it out.
- Allow it to dry according to the directions.
Q. How do you fix hairline cracks in concrete?
The easiest way to fill a hairline crack is to use a liquid crack filler. Squeeze a bead of filler over the crack, then use a trowel to push the filler into the gap.
Q. How long does concrete filler take to dry?
It depends on the material, the width of the crack, and the temperature. Some fillers dry in under an hour, while others can take 24 hours or longer to cure.
Q. How do you remove concrete crack filler?
The easiest way to remove concrete crack filler is to use an angle grinder and grind along the edge of the filler.