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Fix Small Concrete Cracks in less than 5 Minutes

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.

Hydraulic Water Stop Cement

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. Β 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.


Small Concrete Repair Project

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, πŸ™


Concrete Repair with Hammer and Chisel

Here’s a quick video tutorial on how to properly chisel the concrete crack. Click on the video image below.

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(If you like this video click here to subscribe to my YouTube channel πŸ™‚ )

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.

Cleaning Concrete Crack After Chiseling

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.

Small Container for Mixing Hydraulic Cement

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.

Using a Margin Trowel to Mix Hydraulic Cement

Mold and press the hydraulic cement with your hands (using chemical resistant gloves) into the small concrete crack.

Press Hydraulic Cement Into the 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).

Patch Exposed Concrete Aggregate

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.

Fill in Deep Cement Cracks with Sand

Fill in Cement Cracks Up to One Half Inch from the Top with Sand

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. Β This was done for both the horizontal and vertical hydraulic cement joints on this project.

Jointer Tool for Finishing Mortar Joints

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.

Clean Off the Area Around the Concrete Repair with a Wire Brush

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.

  1. Enlarge the crack with a hammer and chisel
  2. Undercut the crack or create a U-Shape to ensure the new cement will adhere
  3. Clean out the crack with a brush or leaf blower
  4. Use a small container like a yogurt cup to measure the hydraulic cement first then your water
  5. Place the hydraulic cement into a small plastic bucket and mix in the water using a margin trowel
  6. Quickly work the hydraulic cement into the cement crack. You have 2-3 minutes. Work Fast!!
  7. Only add enough hydraulic cement to fill in 1/2 inch of the crack at one time.
  8. Add sand to deep horizontal cracks to within 1/2 inch of the top of the crack.
  9. Shape the hydraulic cement with a jointer tool.
  10. Clean off excess hydraulic cement with a wire brush or margin trowel.
  11. Tools: hammer, chisel, margin trowel, wire brush, jointer, brush or leaf blower, hydraulic cement, yogurt cup, small plastic bucket, sand
Thank you all for reading this post, and if you already haven’t done so, please click on the links below to subscribe to my Facebook page & YouTube channel where your can find more tips on home remodeling. Please feel free to share any tips of your own in the comment section below.
Make it a great day!
Home Repair Tutor



23 comments… add one
  • PAM HALL July 19, 2012, 3:46 PM


    • Jeff July 19, 2012, 3:56 PM

      Hi Pam,

      You should use Mortar for tuck pointing instead. The hydraulic cement dries too quickly whereas mortar has plenty of working time. Hope that helps.

  • e burton February 13, 2014, 11:36 AM

    Also live in older(1959) stucco/stone ranch. Your tutorials lead clearly, mention/suggest products I have used in the past and make me more confident to try some of these projects now that I’m retired. Thanks again.

    • e. burton February 13, 2014, 11:39 AM

      I found you on facebook thru a gardening site. If possible, please contact/send info to facebook. Thank you.

    • Jeff Patterson February 16, 2014, 9:36 AM

      Thank you so much for your vote of confidence.

      If there’s anything you’d like me to write about or do a tutorial on please don’t hesitate to ask.

      Home Repair Tutor is driven by the Group’s requests. So I’d be happy to lend a hand πŸ™‚

  • Natalya May 21, 2014, 6:51 AM


    I need to repair a few driveway cracks. I see you have a tutorial on that but is there a reason why you use different product? Can hydraulic cement be used for crack repair on driveways? If not, why is it a bad idea?
    Thank you!

    • Jeff Patterson May 24, 2014, 12:49 PM

      Well Natalya, the crack filler is easier to apply than the hydraulic cement and is specifically made for driveway cracks. It’s more flexible and can be shaped a bit better. So I’d use the cracker filler for your small cracks in the driveway slab.

  • Mark May 23, 2014, 5:17 PM

    I need to fill crack in cinderblock swimming pool. Does the Quikrete Hydraulic need to be primed before painting with a rubberized pool paint?

    • Jeff Patterson May 24, 2014, 12:46 PM

      This is a good question Mark. I’m not sure and would give Quikrete a call if you use their hydraulic cement. They’re pretty nice on the phone.

      It wouldn’t hurt to call the company that makes the paint, too. That way you’ll have a well rounded opinion on the matter and be able to make an informed decision.

  • gina September 4, 2014, 9:06 PM

    do you have a video or detailed instructions on how to apply mortar mix between red clay house bricks

    • Jeff Patterson September 5, 2014, 7:35 PM

      Not yet Gina but I have to do this on my own brick. It’s not red clay but the same technique would apply. I hope to get that video up soon.

  • Karen February 18, 2015, 6:11 PM

    Hi Jeff, I just found your website and am impressed with the quality and thoroughness of your explanations. I have a concrete utility sink that has hairline cracks and is pitted in places. My washing machine water drains into this sink. After a load or two, the sink will slowly leak. I recently scrubbed the inside of the sink with a slightly alkaline concrete cleaner and it’s now dry. It was this process that revealed just how many hairline cracks and small (less than 1/16″ diameter) pits there are. Laundry is piling up and I need to get this sink back to being functional. I have previously patched hairline cracks with JB Weld epoxy, which worked wonderfully, but my stash is getting too thick to use. What product(s)/process do you suggest I use to make this sink water-tight? Please don’t suggest a sledge hammer as removing the sink is not an option right now. I’m hoping to minimize purchasing new material, although I certainly will if needed. BTW, I already have on-hand a variety of penetrating sealers and some garage floor paint/epoxy, in case that’s useful info for you. Thank you in advance for your advice. I’ve bookmarked your site and look forward to more of your wisdom.

    • MSeymour May 20, 2016, 10:38 PM

      I have the same issue as Karen. I have a cement slop sink that is wearing and black, rough stone is showing through the base around the floor of the sink and on one side of the drain its all worn through (about a 4″x4″ area) and completely rough black stone. I wanted to know if I should be sealing it or putting a layer of concrete over it to prevent further wear and possible leaking. Any advice?

  • Fuller Ming March 5, 2015, 7:12 PM

    I tried to use this with an active leak. I’m not the greatest handy-man. The mixture got wet as the water seeped through. How can this be used underwater? How can I patch and active leaking basement wall? It doens’t have to look pretty when I’m done – it’s under the crawl space under the stairs, all concrete, and used as storage.

  • rosa April 19, 2015, 2:55 PM

    Thank you Jeff for the video on undercutting! I wasn’t understanding how to do it or why it needed to be done until now. πŸ™‚

    • Jeff Patterson April 21, 2015, 6:16 AM

      My pleasure to help any time Rosa. Keep me posted on your project πŸ˜€

  • Roger January 18, 2016, 11:24 AM

    Hi Jeff,

    I have heard that mixing hydraulic cement with beer instead of water makes it workable for a longer time before it sets (and the scent dissipates completely) – any truth to that?

    • Jeff Patterson January 19, 2016, 6:59 AM

      Depends on how much beer the user consumes…just kidding, I’m not sure if that’s true or not Roger.

      Sounds like we’d have to do a test to see, that would be a fun one

  • Zequek Estrada March 21, 2016, 8:48 PM

    I’ll have to try and see if the local stores around carry hydraulic water-stop cement. It sound convenient and easy to use. I would also love if I could fix some of these cracks on our porch.

  • Jack Palmer March 28, 2016, 8:09 AM

    I love how you compared hydraulic water-stop cement to play dough! It makes me want to try it out. Last night we were out in our front yard and I noticed that we had some cracks in our cement driveway, I was pretty surprised since our property is relatively new. It’s nice to know that there are options to fix it. I’ll have to look into it a little more next week. Thanks for the info!

    • Jeff Patterson April 1, 2016, 5:08 AM

      Thanks Jack, I’d recommend crack filler for small cracks over the water-stop cement. It’ll serve you better and is easier to apply πŸ™‚

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