
Grinding out cracks in a concrete patio is a simple and relatively inexpensive DIY project that can help prevent bigger problems down the line. Concrete slabs can crack for many reasons, including repeated freezing and thawing, heavy loads, tree roots, and ground shifts. By grinding out the cracks, you can clean and open them up, allowing for a filler or sealant to be applied, which will help maintain the structural stability of the patio. This process can also help to prevent weed growth, debris collection, and trip hazards. When grinding out cracks, it is important to wear the proper safety gear, such as rubber gloves, safety glasses, long sleeves, and long pants, to protect yourself from concrete debris.
Characteristics | Values |
---|---|
Working Time | 45 mins |
Total Time | 1 day, 45 mins |
Skill Level | Beginner |
Estimated Cost | $10 - $30 |
Safety Equipment | Safety glasses, hearing protection |
Tools | Heavy-duty flat mason's chisel, wire brush, shop vacuum, hammer, putty knife, trowel |
Materials | Polymer-based (sanded acrylic-latex) filler, closed-cell backer rod, clean sand, funnel |
What You'll Learn
Safety equipment to wear when grinding concrete
When grinding concrete, it is important to wear the appropriate personal protective equipment (PPE) to protect yourself from potential safety hazards, such as flying particles, dust, noise, and vibration. Here is a list of safety equipment you should consider wearing:
- Eye Protection: Safety goggles or glasses are essential to shield your eyes from concrete dust, flying debris, and potential chemical splashes. Choose shatterproof goggles that can resist heavy impacts.
- Respiratory Protection: A face mask or respirator is crucial to safeguard your lungs from inhaling concrete dust, especially silica, which can lead to serious respiratory problems and illnesses like silicosis, bronchitis, and asthma. Look for masks with ratings such as P-95, N-95, or R-95.
- Hearing Protection: Concrete grinders can generate high noise levels that can cause permanent hearing loss over time. Wear earplugs or other suitable hearing protection to safeguard your hearing.
- Hand Protection: Alkali-resistant gloves are recommended to prevent skin irritation and chemical burns from the chemicals in the cement. If you're using a corded grinder, insulated gloves are crucial to prevent electric shocks.
- Footwear: Sturdy boots, preferably alkali-resistant and steel-toed, will protect your feet from heavy objects, falling debris, and chemical burns.
- Clothing: Long sleeves and full-length pants are important to reduce skin exposure to concrete dust and chemicals. Covering your body fully helps protect your skin from irritation and burns.
Additionally, it is important to work in a well-ventilated area to minimise the risk of inhaling concrete dust. Always follow the manufacturer's instructions and ensure you are properly trained in using and maintaining concrete grinders.
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How to identify if cracks are serious
Concrete slabs will inevitably crack, but how do you know if the cracks are serious? Here are some ways to identify whether the cracks in your concrete patio are indicative of a more serious underlying problem.
Firstly, the depth and width of the cracks are important factors in determining their seriousness. Very fine surface cracks, or "crazing", are usually cosmetic and not signs of serious structural damage. These fine cracks are often caused by concrete drying too fast. Hairline cracks or cracks under 1/4-inch wide may not indicate serious underlying damage, but they can get bigger over time if water gets into them and temperatures drop, causing the water to freeze and expand.
On the other hand, cracks that are deeper than 1/4-inch or wider than 1/2-inch usually signal more serious problems. While these cracks can be filled, the fix is often temporary. If the cracks are bigger than an inch wide and uneven, they almost always indicate underlying structural issues and can become tripping hazards. In such cases, it is recommended to consult a professional.
Additionally, the location of the cracks can be indicative of a problem. Foundation settlement cracks, for example, are usually found around the corners or perimeter of buildings in the form of a stair-step pattern. Structural cracks are also serious and can compromise the integrity of the concrete structure. They may appear as wider cracks (1/8-inch or more) and often extend through the entire thickness of the concrete. These cracks can allow water leakage and cause the structure to become unstable.
Finally, the cause of the cracks can help determine their seriousness. For example, if the cracks are due to subsidence or other earth-shifting issues, it may be necessary to address these problems first before repairing the cracks, as they are likely to reappear. Overloading cracks, which occur when excessive weight is put on a concrete slab, can also be a concern.
In summary, while some cracks in concrete are normal and to be expected, others can indicate more serious underlying issues. It is important to identify the depth, width, location, and cause of the cracks to determine their seriousness and take appropriate action.
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How to widen cracks for better filler adhesion
Widening cracks in a concrete patio will help the patch material stick better. Here is a step-by-step guide on how to widen cracks for better filler adhesion:
Safety First
Before you start, put on some safety glasses and hearing protection. Working with concrete can be noisy and produce a lot of dust, so it is important to protect your eyes and ears. Long sleeves and long pants will also help protect your skin.
Widening the Crack
Place the edge of a masonry chisel into the crack at a 45-degree angle. Using a hammer, lightly tap the back of the chisel to force it about 1/4-inch into the crack. Continue to follow the crack, tapping gently and being careful not to chip out large sections of concrete. Try to maintain a width-to-depth ratio of 2:1.
Remove Loose Debris
Use a wire brush to vigorously brush the crack and remove any remaining small particles. Brush in the direction of the crack. Once you have removed as much as you can with the brush, use a shop vacuum to remove the smaller debris and dust.
Assess the Depth of the Crack
If the crack is deeper than 1/4-inch, you will need to fill it with a solid crack filler to bring it up to a 1/4-inch depth. Liquid crack filler is not ideal for deep areas as it extends curing time, can result in sinking filler, and adds to the overall cost of the project.
Add Solid Filler
There are a few options for adding solid filler. One method is to use clean sand, which is inexpensive and allows you to vary the height of the crack filler as you go. Simply dispense the sand through a funnel into the crack. Another option is to use a closed-cell backer rod, which is designed to fit into 1/2-inch cracks. Force the backer rod into the crack with your fingers, and cut it off when you reach higher areas that do not need filler. For deeper sections, use a blunt tool such as a paint-stirring stick to push the backer rod into place.
Prepare the Area
Before applying the concrete crack filler, make sure the area is clean and dry. Remove any old caulking or concrete patch materials with a hammer or chisel, and use a slotted screwdriver to dislodge any remaining pieces. Pull out any weeds or grass growing in the cracks, and remove leaves and other debris with a broom, leaf blower, or shop vacuum. Finally, fill a pressure washer with a concrete outdoor cleaning solution and apply it to the area, following the manufacturer's instructions. Allow the area to dry completely before moving on to the next step.
Apply the Concrete Crack Filler
Cut off the end of the applicator tip and shake the crack filler container if necessary. Some fillers may need to be mixed before use. Squirt a small amount of filler onto a piece of cardboard to test it. Once you are ready, force a bead of the filler into the crack, slowly drawing it along and ensuring that it fully settles into the crack before moving on. Use a putty knife to flatten any high areas and fill in any low spots with additional filler. Let the patch material cure for at least 24 hours before walking on it or painting/surfacing the patio.
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The best fillers for concrete cracks
Concrete slabs can crack for a variety of reasons, including repeated freezing and thawing, heavy loads, tree roots, and shifts in the ground. Luckily, repairing cracked concrete is a simple and relatively inexpensive DIY project.
When fixing cracks in concrete, it's important to consider the location and size of the crack, as well as whether the crack is on a horizontal or vertical surface. For cracks in high-traffic areas, such as a driveway, you'll want a filler that can withstand a lot of use. If you're a beginner, look for a product that is easy to apply and doesn't require special tools.
- Sika Self-Leveling Sealant: Best for overall use. Can be used for cracks between 0.25 and 1.5 inches wide and 0.5 inches deep. It is flexible, waterproof, and can be painted or stained. However, it has a long curing time of 3-5 days.
- Sashco Slab Concrete Crack Filler: Best value for money. Can fill cracks up to 3 inches wide on sidewalks, patios, driveways, and other horizontal surfaces. It is flexible, paintable, and odourless. However, it has a long cure time of 1 week.
- RadonSeal DIY Foundation Crack Repair Kit: Best for foundation cracks. Seals cracks up to 0.5 inches thick in basement foundations and concrete walls, preventing water, insects, and soil gases from penetrating. The application process is somewhat complex and requires multiple steps.
- Red Devil Premixed Concrete Patch: Best for large cracks. Comes in a ready-mixed tub or tube and is suitable for repairing large cracks in sidewalks, walkways, and patios. It adheres well, dries to a light concrete colour, and doesn't shrink or crack. However, it is not suitable for driveways.
- Quikrete Concrete Crack Seal: Best for thin cracks. Easy and affordable, this product can repair hairline cracks in horizontal concrete surfaces. It is self-levelling and dries to a hard but flexible finish. However, it is only suitable for cracks up to 0.25 inches deep.
- UGL Drylok Fast Plug Hydraulic Cement: Best drying time. Sets within 5 minutes and is suitable for patches in various masonry surfaces. Can also be used to anchor metal to concrete. The fast-setting nature requires quick work and small batches to avoid waste.
- PC-Concrete Anchoring and Crack-Filling Epoxy: Best epoxy. Fast cure time of 4 hours and suitable for horizontal and vertical cracks. Strong and waterproof, but more difficult to dispense due to thicker texture.
- DAP Liquid Cement Crack Filler: Best liquid filler. Easy to use and ideal for filling hairline cracks up to 0.5 inches wide. Self-levelling and paintable, but not suitable for vertical surfaces.
- Crack Stix Permanent Concrete Joint & Crack Filler: Best flexible filler. Fast-setting and ideal for sealing expansion joints and mid-size cracks. Can be applied at temperatures as low as 32 degrees Fahrenheit. However, it is more expensive and not as easy to shape for smaller or larger cracks.
- Rust-Oleum Concrete Patch & Repair: Best for industrial-strength repairs. Two-part epoxy that dries stronger than concrete and covers over 14 linear feet of cracks. Low odour and suitable for indoor and outdoor use, but requires mixing before use.
- Loctite PL Self-Leveling Concrete Sealant: Best for affordability and ease of application. Polyurethane-based formula ideal for joints and cracks in interior and exterior concrete slabs. Self-levelling and affordable, but has a long curing time of up to a week.
- Damtite Waterproofing SuperPatch: Best for large projects. Waterproof patching compound that can be applied in layers up to 3 inches thick. Requires mixing but has a fast setup time, adhering well to vertical and horizontal surfaces.
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How to prevent future cracks
To prevent future cracks in your concrete patio, it's important to take precautions during the installation process and the first week of curing. Here are some detailed instructions to help you achieve that:
- Use High-Quality Concrete: The concrete you pour should be of high quality, with the proper ratio of water, cement, and other ingredients. This is crucial to ensure the strength and durability of your patio.
- Slow Evaporation: During the first week of curing, spray the concrete with water several times a day to promote slow evaporation. This is especially important if the weather is hot and dry.
- Protect from Cold Temperatures: If temperatures dip below 50°F (10°C), cover the concrete with a concrete insulating blanket during the first week. Only remove the blanket when the temperature rises, and continue spraying the concrete with water.
- Add Control Joints: Consider adding control joints, which are cuts made with the intention of creating weak spots for future cracks. This helps decrease the likelihood of random cracking.
- Compact the Base: Ensure that the base you're pouring the concrete onto is well compacted. This provides a stable foundation for your patio.
- Reinforce with Strong Materials: Reinforce the concrete with rebar, mesh, or other strong materials. This will enhance its strength and reduce the chances of cracking.
For existing concrete patios, follow these tips to prevent cracks:
- Ensure Proper Drainage: Make sure your yard's drainage is functioning correctly. Water and ice can cause damage to your concrete, so proper drainage is essential.
- Annual Power Washing: Clean your concrete annually with a power washer to remove any dirt, grime, or debris that could contribute to cracking.
- Reseal Regularly: Reseal the concrete every few years to maintain its protective coating. This will help prevent water infiltration and cracking.
- Remove Nearby Trees: Trees close to a concrete patio or driveway can cause damage due to root growth. Consider removing them to protect your concrete.
- Avoid Salt and De-icers: Avoid using salt or chemical de-icers on your concrete during winter. These substances can harm the concrete and contribute to cracking.
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Frequently asked questions
Before grinding out the cracks, it is important to clean the patio thoroughly. You can use a pressure washer with a concrete outdoor cleaning solution to remove any dirt, mould or stains. Additionally, remove any weeds, grass, or debris from the cracks using a chisel, screwdriver or broom. Ensure the patio is dry before proceeding with the grinding process.
To effectively grind out the cracks, you will need a heavy-duty flat mason's chisel and a hammer. Put on safety glasses and hearing protection for your safety. Place the chisel into the crack at a 45-degree angle and lightly tap the back of it with the hammer to force it about 1/4 inch into the crack. Follow the crack, being careful not to chip out large sections of concrete, and maintain a width-to-depth ratio of 2:1.
For cracks up to 1/2 inch wide and 1/4 inch deep, use a polymer-based (sanded acrylic-latex) filler. Inject the filler into the crack with a caulking gun and smooth it over with a putty knife. Choose a filler that closely matches the colour of your patio to minimise its visibility. Allow the filler to cure for at least 24 hours before using the patio or applying any paint or surfacing.