# Hydraulic Cement



## Red Truck (Feb 6, 2010)

Any one know the trick to making hydraulic cement work? Every time I try to plug leaking concrete walls or floors the water still leaks through the applied cement. It says you can use it under water. Does it have to be thick, like putty to work right? Please advise.


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## tpolk (Nov 7, 2009)

i think depending on size of crack you may need to make larger depending on size. also prep/clean is important and not sure if a bonding agent can be used with it


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## Daniel Holzman (Mar 10, 2009)

I have never had any problem with hydraulic cement, except if it is old. Old cement absorbs water, and does not work very well. For typical applications, you just need to wet the powder up slightly to make it into a moldable ball, then force it into the leaking gap. The water will cause it to harden. By the way, use gloves, the cement will turn your skin into soap, very caustic.


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## Red Truck (Feb 6, 2010)

I chiseled out the crack to enlarge it...very hard wall. Is there a better way other than a chisel?


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## Red Truck (Feb 6, 2010)

Daniel,
So is it important that it's thicker and can be molded into a ball and not a thinner consistency where you would spread it on the wall?


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## Termite (Apr 13, 2008)

With cementitious products, more water = less strength. If you're making it too soupy it won't work as well. Mix just enough water to make it a plastic consistency (about the stiffness of peanut butter). Clean the gap you're filling, either with water or with compressed air, to ensure a good bond. Pack it in as far and as hard as you can.


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## Thurman (Feb 9, 2009)

Proper consistency (peanut butter) is good, and proper packing are the keys. Make a ball of the mud appropriate to the crack size, tamp it in with a small piece of wood. Get it into the crack, not just on it. I start at the top and work down. David


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## concretemasonry (Oct 10, 2006)

A thin mixture or spreading it on a wall or shallow is just a waste of time.

The cement must be stiff and forced into a clean crack that confines it. As it begins to set, it expands slightly, locking into the crack. It can even be applied to damp concrete.

Dick


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## Ron6519 (Mar 28, 2007)

Drilling out the crack makes the job much easier and it gives you the proper wall configuration you need for the material to work properly.
The crack will probably run to the floor so drill it out completely The walls of the drilled out opening should be parallel to one another or wider at the bottom of the opening.
The crack needs to be flushed our from top to bottom. Have on hand all the material you need. I like to set up a series of containers with the dry material ready to be mixed. Only mix what you can apply in 60 seconds or so as this material sets up very quickly. Some hydraulic cements set up slower then others, but none of them take more then 5 minute to start setting.
Keep a large bucket of water handy to clean the tools and wash your hands. Mix up the first batch and push it firmly into the bottom of the crack. Work your way up from the bottom of the wall to the top. As soon as you finish one batch, wash the tools and mix the next batch. The aim is to try to get as close to a continuous "pour" as you can. You can leave the material a little high and shave it down flush with the wall as long as you don't wait too long.
I open the crack to about 3/4"-1" wide so I can pack a good amount into the opening. The cracks rarely hapen perpendicular to the wall, so follow the crack with the masonary bit. Older concrete foundations are easier to follow as the cracks are usually softer around the crack itself. Sometimes they are filled with sand. You should have a spray bottle handy to flush out the area so you can follow the path of the crack up the wall.
This type of repair will not be permanent. I've had them last about 8 years or so. The better control you have of the surface water at grade, the longer the repair will last. My experience is with the sandy soils of Long Island, NY.
Ron


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## concretemasonry (Oct 10, 2006)

I was involved in a dam repair job. They use a similar method to what Ron suggested. They tried to scrape it off flush. The next day, they misted the concrete with water and applied a thick coat of Thoroseal for additional protection and make any future problems more evident. Those old hollow dams moved a bit from season to season.

Dick


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## Red Truck (Feb 6, 2010)

Can it be applied when the water is still coming in? 
I chiseled out the crack, made a peanut butter like consistency with the cement, balled it up and stuffed it into the crack. It held back some water but the water was starting to washed away the cement.


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## Daniel Holzman (Mar 10, 2009)

Theoretically hydraulic cement will work when water is flowing, but in my experience it is tough to keep it in place long enough to harden. You may want to consider using epoxy to fill the cracks. There are some interesting mixes of epoxy that can be injected using a syring type device, or an air pressure controlled nozzle, that will harden rapidly and can tolerate a small amount of flowing water. Search for epoxy crack repair. The Sika Corporation has a wide range of epoxy products, some of which are specifically designed to minimize water intrusion through concrete.


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## jomama45 (Nov 13, 2008)

There are also some specialty product you can get at a concrete supply yard as well. One of the names I remember was "Dam-It". There was another that used to be more common, just can't think of the name now. It sounds alot like the same material Ron is talking about. It set's REALLY fast. You will feel the heat coming off of it through the rubber gloves.

My dad taught me years ago, get it just wet enough to form a ball, put it on your fist, & "pound it home!" This stuff would set-up within 30 seconds, at least to the point that it would stay in place and stop running water.


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## Ron6519 (Mar 28, 2007)

Red Truck said:


> Can it be applied when the water is still coming in?
> I chiseled out the crack, made a peanut butter like consistency with the cement, balled it up and stuffed it into the crack. It held back some water but the water was starting to washed away the cement.


There are caveats to all products and applications. It's generally up to the person doing the job to determine the success level expected based upon the current conditions.
This is where experience trumps optimism.
Ron


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## concretemasonry (Oct 10, 2006)

A peanut butter consistency is probably too wet to be stable long enough to set in place properly. You have to be able to force it in.

Dick


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## SpinMd (Jul 6, 2010)

*hyrdaulic cement questions...*

Dan, Red Truck, Ron, and everyone else who has used any type of sealants for water. PLEASE, let me know your thoughts on this. 

I have a double wall 48" diameter culvert pipe that I have finally sealed off successfully on one end, only to now find that there is a small slash in it with water coming out. This pipe used to be part of the overflow basin that allowed the water to exit our 6.5 acre pond. Regardless, how do I seal it? DAM-IT seams to be an answer, hydraulic cements, epoxy's specifically for use with water all seam good solutions as well, but the pipe is plastic, so what works best with a plastic double wall pipe configuration with a 1/2"-1" vertical slash in it with water coming out? The biggest challenge seems to be how to get the product injected into the small, not flexible slash where the water is coming out of. It is so small that sticking the stem of a cauck tube is very challenging. Ok, I'll shut up now and await your response. Thanks everyone!


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