Do you have concrete surfaces that have seen better days, but don’t know what to do with them? Or maybe your concrete has just started to crack, but you don’t know how to fix concrete damage before it gets worse?
Small damage on the concrete surface may be unsightly, but will not affect the overall structural integrity of the slab if it is fixed when it appears. Fixing concrete damage requires removing crumbling bits, filling cracks, and resurfacing as necessary.
For those who want to do this maintenance themselves, I’ve done a six-step guide to doing it as efficiently as possible. All the tools that are needed are basic ones so it will be easy to get them.
How to fix concrete cracks
Step 1: First you need to remove any crumbling concrete with a cold chisel and ball peen hammer. Use a brush to remove the bigger concrete pieces from the crack so you will see what you’re doing.
Continue enlarging the cracks to form an inverted V shape with a cold chisel. This will allow you to patch the crack but prevent the concrete patch from popping out over time.
When the crack is in V shape, the concrete will have more area to adhere to and the patch will be more durable. No need to go overboard though.
When you’re done with the removal of crumbling concrete and enlargening cracks, clean big pieces of concrete with the brush and use a wet/dry vacuum to clean the rest of the dust. It will be easier to vacuum if you take the rough waste manually first.
Step 2: Next you need to apply a layer of concrete bonding solution to the surface that will be touched with the concrete patch. With V-shaped cracks, apply it to the chiseled crack. If there are holes, use it to the inner sides of it.
Try to get it only at the places you will patch as it will show everywhere else. After you’ve gone through all the spots you will patch, leave it to dry. The manufacturer’s label should have the time and you will notice it when you touch it as well.
Step 3: Now you mix enough patching concrete with water to fill all of the cracks. Pay particular attention to the ratio of water and concrete mix: too much water and the concrete will prematurely crumble. Also, if you’re patching walls it will be hard for it to stick into it as it’s too much like a liquid.
Force the patching concrete into the crack using a trowel. If you have bigger holes, use a finishing trowel as well to help you patch it level. Feather the edges of the crack patch so it blends with the surrounding surface. A sponge float, for example, is good for this as it will level the edges, you just need to press all the water out of it before you start. Allow the crack to cure covered with plastic for several days.
TIP: Use a trowel, brush, or float to mimic the pattern of the surrounding concrete slab on the surface of the concrete patch. You need to wait a bit for the concrete patch to cure as if it’s wet, those tools will just eat away your patched surface.
When the surface is hard enough to touch without leaving a mark, but still moist, use the tools to give texture.
Step 4: Examine the surface of the concrete. If it is in relatively good condition, you can stop with the repairs. If it is in somewhat poor condition, you should proceed and resurface the entire concrete slab.
If the concrete slab has undefined edges, build formwork along the sides of the concrete slab that extend 2-4 inches above the existing surface. You don’t have to fill the entire form, it will just help to make straight and sharp edges as the leveling compound doesn’t just fall over the edge.
If you are resurfacing a slab that has a defined edge, such as a wall, remove any obstructions that would prevent you from adding a thin layer of mortar over the existing slab.
Step 5: Clean the concrete slab thoroughly. Like with the cracks, it will help the bonding agent to adhere. Then you apply the concrete bonding agent to the surface of the slab. Coat the inside surface of any formwork with a light film of vegetable oil. This will help when you remove the forms.
Step 6: Check how thick the manufacturer label lets you level. Don’t go over that as the self-leveling compound will probably crack. bigger fills need to be done before you do the final surface.
Mix self-leveling compound according to the manufacturer’s instructions. You should mix enough self-leveling compound to cover the whole surface of the concrete if you feel comfortable doing that kind of area.
Pour the self-leveling compound onto the concrete slab. Pour it in several areas and spread it with a trowel. Over several minutes, if properly mixed, the self-leveling compound will coat the concrete with a thin coat of concrete.
Step 7: After the concrete has cured for 12 hours, remove any formwork. This way you can remove the forms easily without it cracking the edges. You can use a sharp tool to slice the border of the slab and form it so it will be sharp. Allow the concrete to cure for 24 hours before walking on it.
Now you just wait as long as the manufacturer label says. It might be 2-3 days. Some self-leveling compounds need to be watered a little the next two days, info will be on the same label. Just remember that a small spray of water is enough, just to moisten the surface. If it gets pouring wet it might weaken the compound.
Now you should know how to fix concrete cracks and small holes and even level the surface. Remember that the products are a little different around the world, not all need bonding agents, and so on. Pretty much all the polymer fiber compounds I’ve used are fine to use without it.
What is consistent is that the surface must always be clean before you do patching. If there is no bonding agent, the cracks and holes need to be moistured a bit for better adhering.
You can imagine it trying to spread concrete on dust. It’s not going to get below the dust if you don’t clean it. The same is with dusty concrete cracks, if the pores are filled with dust, the concrete fix won’t be getting there.
Make your patches clean before fixing and you do better than all the professionals who don’t do it.