When building homes and structures, the goal is to always come up with a foundation that can stand the test of time. This is one of the reasons why people tend to opt for concrete instead of using weaker materials.
However, concrete is also prone to damage caused by a confluence of factors, leading to the formation of cracks on the surface.
Table of Contents:
- Why Does Concrete Crack?
- Most Common Causes of Damage to Concrete:
- Factors to Consider While Selecting the Right Concrete Crack Filler
- 5 Best Crack Repair Kit (Review & Buying Guide)
- Types of Concrete Crack Fillers
- Frequently Asked Questions
Why Does Concrete Crack?
When concrete gets cracked, it could be a sign of compromised structural integrity. This means the structure could be at risk of collapsing and endangering its occupants, although not all the time.
Before it reaches this point, repairing cracks in the concrete is highly recommended and this can be done with the help of the right concrete filler.
There are plenty of reasons that could cause concrete to crack, but these are generally divided into two categories: structural cracks and nonstructural cracks.
Structural cracks refer to those that are caused by issues with the overall design or problems during construction. It could also be caused by overloading or failing to construct a solid foundation.
These types of cracks are often the reasons why structures are deemed unsafe, which means they have to be fixed or restructured right away.
Nonstructural cracks, on the other hand, are typically due to internal factors that affect the materials used during construction. Although they are not usually considered dangerous for occupants of the structure, they ruin the aesthetics and may cause one to feel unsafe inside the structure.
Most Common Causes of Damage to Concrete:
While not ideal, excessive mixing of water in the cement mix is a common practice for developers because it makes placing concrete so much easier. However, this affects the quality of the material by reducing its strength or making it porous and more absorbent of water. This causes the concrete to require repairs every so often.
Poor design planning
As previously mentioned, lapses in the design could gravely affect the strength of the concrete. A common example would be when the concrete is not enough for the total load it is meant to support.
Another case is when electrical outlets, conduits, and other embedded items are placed close to the surface of the concrete. When cracks form around these objects, there is a possibility for moisture to seep into the concrete and cause damage.
Defects in construction
Also considered as a common cause of damage in concrete are construction defects such as rock pockets and honeycombs, as well as finishing defects. Rock pockets and honeycombs refer to large holes or voids that are formed when the concrete does not fill the spaces completely.
Corrosion in the reinforcing steel
The addition of reinforcing steel, also sometimes referred to as rebar, is necessary for construction because it provides tension support to the concrete.
Due to its chemical structure, steel is very much prone to corrosion when water seeps through or air flows into the concrete. This could also affect its ability to support the structure, possibly leading to cracks in and out of the surface.
Factors to Consider While Selecting the Right Concrete Crack Filler
The job begins with knowing what the problem is. Before you try to get your hands on a concrete crack filler, you should first identify the cracks, chips, or dents that you are trying to address, especially its size and causes. This way, you can easily identify the proper solution.
For every concrete crack width, there is a corresponding product that does the filling best. Assess the size of the crack that you want to fill in first, so you can select the best option in the market.
For smaller cracks, a sealant or caulk could be the better choice, while narrow ones might need an epoxy injection. Bigger cracks call for cement-based products because then you will have an opening that is big enough to squeeze the mixture in.
In some instances, you simply do not have the time (and patience) to wait for several days or a couple of weeks for your cement mix to cure. However, this is a very important part of the construction process.
When repairing cracks in the concrete, especially if you are planning to pour another layer of mixture, you also need to consider the time it takes for it to cure. Look for products that help facilitate faster curing, so you can finish the repairs as quickly as possible.
Ease Of Use
Filling concrete cracks may seem like an easy feat, especially if you are looking at tiny gaps and narrow cracks. But do not be misled. Even the smallest of cracks could be a pain to repair, more so if you are not used to doing this kind of work.
For a simpler approach, look for products that are best recommended for beginners. Try filler or sealants that can be applied directly and do not require mixing.
You may also want to look for products that come with complimentary applicators so there’s no need to purchase a separate one in case you don’t have them at home.
Concrete is a very solid structure, but it also has its limits in terms of the level of heat it can take. Extreme temperatures have a direct effect on the strength of the concrete, which is why it is important to ensure that you are using the correct filler and following the proper procedure.
5 Best Crack Repair Kit (Review & Buying Guide)
The RadonSeal Concrete Foundation Crack Repair Kit is a favorite among DIY-ers for the simple reason that it is much more affordable than hiring a waterproofing expert to work on a foundation crack. This product is ideally used for poured concrete walls that are suffering from water leaks and pest infestation due to cracks.
It comes in an injection-type container that makes the application quicker, simpler, and easier. Since it is sold as a kit, it doesn’t require a professional to do the job. You can work on the cracks on your own just with the help of a standard caulking gun. It can be used on settling cracks, cold pour joints, corner cracks, and form ties.
This product is made of a two-component polyurethane that expands up to 20 times its volume, allowing it to fill the spaces within the cracks completely.
The low-viscosity of urethane also makes the RadonSeal Foundation Crack Repair filler ideal for hairline cracks that are up to ½-inch wide and 10 or 20-feet long. It is also proven to repel water and prevent shrinking over time.
What makes the RadonSeal Foundation Crack Repair Kit even better is that there is no drilling and excavation required. You can save a ton of money from major repairs with the help of this product.
Another product that is highly raved about by experts is the Aqua-X 11 Clear, Penetrating Concrete Sealer. It comes in 1-gallon and 5-gallon sizes, which you can choose from depending on the number and size of cracks you need to fix.
Unlike the RadonSeal Concrete filler that is recommended for basement walls, the Aqua-X 11 is ideal for concrete driveways, patios, unglazed cement tiles, garage floors, and concrete retaining walls.
The main purpose of this sealer is to protect the concrete from mold and mildew, salt damage after sealing, as well as damages caused by spalling, pitting, and the freeze/thaw cycle.
Each gallon of the Aqua-X 11 Concrete Sealer can cover 600 square feet of surface, which is twice the amount of space for other sealers in the market. One coat of the product is also enough to provide the protection that you need, so a single container can definitely give you a good value for your money.
With its spray-on application, you wouldn’t need to break your back and strain your muscles at work. It also prevents spillage and makes cleanup so much easier.
Moreover, there won’t be problems even when you have kids at home while using the product because it is 100% solvent-free. You wouldn’t hear complaints about the foul odor and no one will be at risk of exposure to harmful chemicals.
The Aqua-X 11 Concrete Sealer dries quickly. If you are using it on pavements and driveways, you only need to wait one hour before allowing foot traffic on the surface and two hours for vehicle traffic. Its effect can last up to five years, so frequent reapplication is not necessary.
The Bluestar Flexible Concrete Hairline Crack Filler is another product that highly-recommended for those pesky hairline cracks that always seem to appear out of nowhere. This type of crack is very common in concrete, and while it’s not usually a cause for concern, it can be really unsightly.
Hairline cracks are not easy to eliminate, especially if you are trying to avoid major repairs or reconstruction. So, the best solution is to use a crack filler.
The Bluestar Flexible Concrete Hairline Crack Filler contains a micron-sized product that can easily penetrate through the toughest concrete. With its squeeze-on application, it’s also easier to apply the filler even on the narrowest cracks and tiniest holes.
This product was formulated to remain flexible both in hot and cold weather, so there’s no issue no matter what time of the year you choose to work on your cracks. It also makes storage fuss-free and ensures that the quality of the product is not compromised by the changes in temperatures.
It comes in two shades — light gray and standard gray — so you can decide which product works best for your concrete. It gives the concrete a cohesive look and makes it look like no repairs were made in the first place. It is also ideal if you are not planning to paint over it after drying.
DAP Liquid Cement Crack Filler is a ready-to-use mixture that can be used in repairing horizontal cracks in concrete. It comes in a squeeze-on bottle with a narrow opening to allow the product to seep through hairline cracks.
What’s great about this cement crack filler is tits self-leveling property. This means that as soon as the product dries up after application, it looks smooth on the surface as if no resealing was done.
It gives the concrete an all-original appearance with no cracks and bumps, making repainting or glossing hassle-free.
The product is ideal for both interior and exterior us and it gives off a gray color when it dries, matching most shades of concrete. Upon application, you only need to wait for a good 30 to 45 minutes before allowing traffic if you are using it on pavements, pathways, and floors.
For best results, you can extend the curing time up to one hour, especially for areas with slow traffic.
If you are looking for a product that can also work on other materials such as cinder blocks, stucco, mortar, stone, wood, and aluminum, the Red Devil 0646 Masonry and Concrete Acrylic Sealant could be the right one for you.
This sealant is ideally used for patching cracks in steps and sidewalks, as well as stucco walls, patios, thresholds, and mortar joints. It’s general for external use, so be sure to keep this in mind.
The Red Devil Acrylic Sealant’s formula dries with a textured finish that blends with mortars and like most concrete fillers, it dries up gray, If you are particular with hues, there is no need to worry because you can also paint over this product as soon as it cures.
It is great for preventing water damage that is often caused by cracks in the concrete. It also provides excellent adhesion, so constant reapplication is not necessary. The small tip in the bottle makes the application quick and easy. Cleanup also won’t be a bother because all you need is water.
Aside from the Red Devil Masonry and Concrete Acrylic sealant, the brand also offers other variants in its line of sealants.
Types of Concrete Crack Fillers
The damage caused by cracks on concrete has always been apparent. Luckily for developers and property owners, there are numerous ways to fix them and most of the products are readily available in the market.
One such thing is a concrete crack filler, which is arguably the number one go-to product for repairing concrete cracks.
With the abundance of materials used in construction, as well as the types of cracks that appear in the concrete due to various reasons, there are also several types of concrete crack fillers available to consumers.
If you are on the hunt for the appropriate crack filler, be sure you know which particular type is most suitable for your concern.
Concrete Crack Sealant
A concrete crack sealant is perhaps the most common type of filler for concrete cracks. It is best used for repairing hairline cracks and preventing surfaces from dirt stains, as well as damages caused by corrosion, salting, and the freeze/thaw cycle.
When applied on the surface, it reduces the porosity of the concrete, effectively making it water-resistant.
Concrete sealers are used for both residential and commercial purposes because these products are easily accessible to customers. Most hardware stores carry a variety of concrete crack sealers for you to choose from and they are usually very affordable.
Concrete sealants are generally divided into two categories: topical and penetrating. Topical types are mostly used for visual enhancements and should be applied on dry surfaces.
Penetrating sealants, on the other hand, can be applied on either dry or damp surfaces. They also have a longer life span of up to 5 years compared to the 1 to 5 years for topical sealants.
In terms of formulation, the popular variants are acrylic and epoxy or urethane. Acrylic sealants are cheaper than products that are made of epoxy or urethane.
Although the effects are not as long-lasting, they are easy to use and are great at providing protection from the sun. Epoxies or urethane-based sealants, meanwhile, are highly resistant to acids and abrasion.
Concrete Repair Caulk
A concrete repair caulk is another type of filler that can be used to repair cracks on surfaces. It is often confused with the regular crack sealant because of their similar purposes.
However, the biggest difference between caulk and sealant is the elasticity of the product. Concrete repair caulks are described to be more rigid than sealants when they dry.
There are two main types of caulks: latex and silicone. However, there is also the specialty type, which is where the concrete repair caulk falls in.
Caulks are mainly used for waterproofing and preventing bugs from infesting a structure through cracks and gaps in the concrete. It can also be used in filling gaps in driveways, sidewalks, and plumbing.
One of the biggest advantages of caulks is that they can be exposed to water right after application, unlike concrete sealants that need a curing time of up to one hour. It can also withstand hot and cold temperatures versus other products that can’t take the heat well.
The formula is typically placed in a canister that is made of cardboard or plastic, with a slim tip and plunger on opposing ends of the canister. A caulk gun is also used to ensure the continuous release of the product during application.
Quick Setting Cement
This is a type of cement mixture whose special formulation allows it to develop compressive strength significantly faster than an ordinary cement mixture. As the name suggests, a quick setting cement takes far less time to completely dry, which translates to a shorter wait for areas with high foot and vehicle traffic.
Quick setting cement is ideally used for repairing cracks and filling gaps in curbs, concrete steps, walkways, driveways, and roads. When the mixture is poured, it only takes 5 minutes for the cement to begin setting and it completes after about 30 minutes.
This is definitively faster than the 30-minute initial setting time for ordinary cement and the 24 hours that it takes for the final set.
Since quick-setting cement has a faster setting time, it is more demanding to use in construction as it requires running water and quicker movements from the workers. A small percentage of aluminum sulfate is also needed in the mixture because this the main proponent of the accelerated setting action.
Hydraulic cement is a combination of cement and admixtures that work to prevent water leakage in concrete. Similar to quick-setting cement, hydraulic cement also sets and hardens in a short period of time after being mixed with water. This explains why it is most ideally used in situations and structures that are submerged in water.
The most common uses of hydraulic cement are for repairing cracks in drainage systems, basement walls, manholes, swimming pools, foundations, elevator pits. Chimneys, cisterns, and fountains.
There are plenty of benefits in using hydraulic cement such as faster setting times of three minutes, ease of use, extreme durability that lasts for a long time, cost-effectiveness, and its strength when submerged in water.
This type of product is also non-corrosive, does not shrink, and even allows you to fix pipe leaks without the need to stop the leaking beforehand.
However, there are also minor problems related to its use. For one, hydraulic cement can’t be used in freezing temperatures. During initial curing, the work area also has to be kept at a temperature between 45°F (7°C) and 90°F (32°C). Most importantly, it is only workable for about 10 to 15 minutes. Any minute longer and the hydraulic cement will already have hardened.
Patching compounds are used to fill cracks, holes, and voids that are too large for a smoothing compound or sealant to handle. While these products can easily address hairline cracks, they are most ideally used for grooves and holes that go beyond 5 mm.
Most patching compounds found in the market are cement-based mortars that can be applied on the cracked surface using tools such as a putty knife or trowel. However, there are also others that come in the form of injection, particularly the ones made using polyurethane and epoxy.
When filling cracks using patching compounds, experts do not recommend using products that are based on gypsum because they have high alkali content that can affect the adhesive properties of the product. If the use of these products can’t be avoided, you might want to prepare for reapplication after a while.
The good thing about patching compounds is that they are easy to use. All you need to do is mix the powder and clean water in a container until a mortar is formed.
You can then begin applying it on the surface or using the compound to fill the cracks and leave them for about 15 minutes before trimming the excess mortar and proceeding to the finishing process. Patching compounds usually take an hour to set.
A concrete resurfacer is a product that is made from combining ordinary Portland cement, polymer modifiers, sand, and additives altogether. Its difference from regular cement products is that it requires a very thin application, which should be just about ½ thick at most.
This type of product is considered very strong with a compressive strength of up to 4,500 psi. In most cases, the concrete resurfacer can be stronger than the actual slab of concrete. This means that when applied properly, it produces a very durable structure that can withstand exposure to various elements.
A concrete surfacer is best used for sidewalks, floors, patios, curbs, driveways, pool decks, parking decks, and other areas that typically have a high volume of traffic on a regular basis.
It can be quite expensive than regular cement mainly because of the addition of other products in the mixture and the quality of its results. This is why many property owners tend to use a mortar mix when what they really need is a concrete resurfacer.
While the two products have the same consistency, mortar does not provide the same level of adhesion that a resurfacer does.
If you are looking to renew a concrete slab, is always better to go with a resurfacer to ensure durability. Although a resurfacer is slightly more expensive, it is still more cost-efficient to use than undergoing reconstruction or pouring new concrete into a slab.
Frequently Asked Questions
How to fill large gaps in concrete?
If you are not considering pouring concrete in these gaps, the best way to fill large spaces in concrete is through the use of patching compounds. Mix the patching compound with water until it forms a mortar.
Begin application using a trowel and make sure to keep it protruding a little, then leave for 15 minutes. Remove the excess compound and smooth over the surface before starting the finishing process.
For cracks and gaps that are larger than ½ inch, it is important to start the repair by undercutting the sides. This way, you can be sure that the patching compound will be able to penetrate within the gaps instead of popping out once the concrete begins to expand.
How to fix hairline cracks in concrete?
Fixing hairline cracks is not a complicated process, although it can be quite challenging. The length and width usually seem manageable, but it depends on the crack filler that you choose to use. Your main priority is to fill the crack with a sealant that can penetrate deep into the concrete.
Look for a crack filler that is specifically made for masonry and concrete. Attach the canister to a caulking gun and begin injecting the formula into the cracks. Do not forget to smooth the surface using a putty knife so it’s easier to paint over it once it dries.
How to repair cracks in concrete foundation walls?
Before you begin with the repairs, the first thing you should do is identify the type of crack on the foundation wall. If it’s a hairline crack, there is no cause for concern as it typically does not suggest a problem with the structure. They are completely normal and often occur when the concrete settles.
If you’d still rather get rid of the eyesore on your wall, a concrete filler can do the job. All you need to do is inject the filler into the crack and smooth it out using a putty knife.
Now, if the crack is wider than ¼ inch, you will have to go through a sealing process. You can do this by filling the crack with concrete caulk then smoothing it with a putty knife. You can use a caulking gun for faster and seamless application.
For cracks that are about ½ inch or bigger, a simple caulk wouldn’t be enough. Instead, fill the gap with a patching compound. Once the cracks are filled, don’t forget to seal the foundation wall by applying a waterproof masonry sealer.
How to apply concrete crack filler?
Applying concrete crack filler usually involves injecting the product into the wall, especially if the cracks are short and narrow. Most crack fillers sold in stores today come in a tube-like canister with a fine tip on one end. These liquid formulations can be applied with the help of a caulking gun, which should be attached to the other end of the canister.
For other types of concrete crack fillers that require the mixing of powder and water, a trowel and putty knife will come on handy. Use the trowel the way you would normally use a kitchen spoon.
Make use of its sharp edges to spread the concrete filler evenly. During the finishing process, use a putty knife to smooth everything or use a dry paintbrush to add texture.
Be sure to give the compound ample time to cure before painting or sealing the concrete.
Does concrete crack filler work?
A concrete crack filler does work. However, it requires that you follow the correct process starting from the cleaning and preparation up to the curing and sealing process.
Concrete repairs require patience, especially if you are not using fast-setting compounds on your property. More importantly, different types of concrete crack fillers have varying curing and setting times, and they play a role in the filler’s overall efficacy.
If you want your concrete crack filler to work, do not resort to shortcuts because it could end up compromising the durability of your repairs. Doing so could also lead to bigger problems and costlier repairs.
How long does concrete filler take to dry?
As there are various types of concrete fillers, each consisting of different chemicals, compounds, and additives, their recommended drying times also vary from one another.
For regular cement, it normally takes one hour for the initial set to begin and it could last up to 24 hours for the final setting process. For quick-setting cement, the entire drying process could be cut down to less than half, with the initial setting beginning as early as 30 minutes after the application.
Hydraulic cement, which reacts faster than quick-setting cement, begins setting as early as three minutes after the application. These are the recommended drying times, but if you want to on the safer side, you can give your fillers more time to dry before starting the sealing or painting process.
How to remove a concrete patch?
Your handy trowel is more useful than you can imagine. Aside from using it as an applicator for your patching compound, it can also be used to remove a concrete patch. Of course, there is an easier route and that is by using a concrete dissolver.
It is very easy to find ready-made concrete dissolvers online and in stores these days. Some of them are sold in foam spray types that are non-corrosive and biodegradable. This is the better alternative to acid concrete removers that are more aggressive and could damage the surface of your property.
Concrete cracks are part and parcel of property construction. This isn’t to say that it is perfectly fine to leave them unattended because they shouldn’t be.
However, the appearance of cracks on your concrete walls, pavements, floors, and thresholds are not always a sign of damage. In some instances, the cracks are just signs that the concrete is settling.
This is why it is important to familiarize yourself with the different types of concrete cracks that you see at home or in any of your properties. It helps keep you from worrying incessantly over something that can be easily addressed by a simple crack filler.
In terms of products you can use to repair cracks, gaps, and holes in the concrete, it also pays to know which is most suitable for every purpose. You can save precious time, money, and energy if you educate yourself about the various types of concrete crack fillers available in the market today.
It doesn’t require an expert to know the types of crack fillers that can be used to fix cracks of all shapes and sizes. You only need to invest time in researching your options, especially if you want to reduce the spending on your part.