Who doesn’t love play dough? Just the thought brings a smile to my face with memories of kindergarten and making goofy art projects for my parents. Remember how you could make play dough houses and they would harden like a brick overnight.
The adult version of play dough is called hydraulic water-stop cement and it can help you complete small concrete repair projects in less than 5 minutes. Patching concrete, whether a small or large job, can be daunting. In this tutorial you’ll learn how to eliminate small cracks that can lead to big problems if left unchecked.
Be a Concrete Hero in Five Minutes
The picture below is a crack in a concrete set of steps at one of my rental homes. I’ve noticed it’s increased in size over time. If it doesn’t get patched I run the risk of it splitting the concrete block in half and that’s a much bigger project to tackle. Who likes doing big concrete repair projects? I like to avoid them if possible.
The Quikrete hydraulic water-stop cement I used for this small repair isn’t that different than mortar. It contains portland cement, sand, and special additives. The difference is that the hydraulic cement will set up in 5 minutes whereas mortar takes much longer to solidify. Also, hydraulic cement is a high strength repair material meant to seal water leaks instantly. The working time you have with it is only 2-3 minutes and that’s why you can only do small projects.
Let’s say you have a crack in your basement’s block wall and the situation involves water seeping through a mortar joint or crack in the block itself. Even if it’s raining and water is leaking into your basement you can use hydraulic cement to seal the crack. It can be used both above and below grade, meaning above ground and below ground where moisture is typically present.
You can apply hydraulic cement in pools, fountains, around pipes, conduit, and anywhere water is an issue.
The first step is to enlarge small cracks with a hammer and chisel. This is a really important TIP: the edges of your crack need to be either square or undercut NOT shaped like a V. Otherwise, your concrete bonding will break down over time and the hydraulic cement will just pop out of the crack. Then you’ll have to repeat your concrete repair project,
Here’s a quick video tutorial on how to properly chisel the concrete crack. Click on the video image below.
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After you’re done chiseling the crack you want to clean it with a brush or broom to remove any debris. This will enable the hydraulic cement to properly bond with the old concrete.
Follow the directions of the hydraulic cement when mixing it. In this case, Quikrete calls for 4.5 parts of hydraulic cement to one part water. I like using a small container like a yogurt cup as a measuring device because you’ll only have 2-3 minutes to mix the cement and work it into the small crack.
Dump the hydraulic cement into a small plastic bucket and add the water. Quickly mix it with a margin trowel until it has a play dough like consistency.
Mold and press the hydraulic cement with your hands (using chemical resistant gloves) into the small concrete crack.
Only add enough hydraulic cement to fill the crack by 1/2 inch at a time. Allow the hydraulic cement to dry then add consecutive layers until the crack is completely filled. I decided to add some of my mixture to the exposed aggregate on each side of the crack. This will prevent water from seeping into the crack during natural freeze/thaw cycles (which is nature’s way of chiseling away your new concrete patch).
Since my repair had three sides I decided to fill in the two vertical cracks first and then deal with the horizontal portion. Remember how you should fill in only 1/2 inch of the crack at a time? Well, the horizontal crack in this case was several inches deep. In a circumstance like this you can fill in the crack with sand up to about 1/2 inch from the top of the cement being repaired.
You should mix up another batch of hydraulic cement for the horizontal portion of the crack. Once the crack is filled with the cement you can use a jointer to sculpt and shape it. This was done for both the horizontal and vertical hydraulic cement joints on this project.
Any excess hydraulic cement can be cleaned off the surrounding surface using a wire brush or margin trowel. Be sure to do this as soon as you’re done shaping the cement so your project looks as clean as possible.
If you need to have more working time for your project you can always use quick-setting cement instead of hydraulic cement. You can work with quick-setting cement for 10-15 minutes and it can be shaped just like hydraulic cement.
Quick and Easy Instructions for Small Concrete Fixes
Print this cheat sheet before your next project involving concrete crack repair.
- Enlarge the crack with a hammer and chisel
- Undercut the crack or create a U-Shape to ensure the new cement will adhere
- Clean out the crack with a brush or leaf blower
- Use a small container like a yogurt cup to measure the hydraulic cement first then your water
- Place the hydraulic cement into a small plastic bucket and mix in the water using a margin trowel
- Quickly work the hydraulic cement into the cement crack. You have 2-3 minutes. Work Fast!!
- Only add enough hydraulic cement to fill in 1/2 inch of the crack at one time.
- Add sand to deep horizontal cracks to within 1/2 inch of the top of the crack.
- Shape the hydraulic cement with a jointer tool.
- Clean off excess hydraulic cement with a wire brush or margin trowel.
- Tools: hammer, chisel, margin trowel, wire brush, jointer, brush or leaf blower, hydraulic cement, yogurt cup, small plastic bucket, sand