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My garage area, which is currently just a concrete slab for parking cars on, has a natural spring that pops up just at ground level. The water never stops, and the concrete there is permanently wet all over. Im hoping to create a channel so that the water is funnelled around the sides of the concrete base, and later into a pond area set below the concrete. My problem is how to fix some kind of guiding masonry such as a row of bricks, onto the floor in a way that will be totally waterproof - but which will also fix to the floor, which will be wet during the process. Is there a concrete or similar material which will glue itself onto a very wet concrete base? Failing that, any other ideas for how to create a channel that will send this water around the sides of my concrete base, and not leave it covered all over? Any help appreciated.

The concrete base area - you can see how wet it is.

The spring emerging from the brickwork

  • Are you sure the water isn't also percolating up from below? You may resolve the surface flow but not the wetness. – isherwood Jul 20 '18 at 14:24
  • Is that built into a hillside? – Harper Jul 20 '18 at 16:44
  • What about boring holes in the base of the wall (inside) and inserting tubing to intercept the flow and direct it outside the concrete area? – Jim Stewart Jul 20 '18 at 16:52
  • A more normal solution would be to bore a hole horizontally outside of at the base of the slab and insert perforated pipe drains or this new product Domos Hydroblox. mkt.domoswater.com/… Given the amount of water coming out you might want to bore along the side and along the back – Jim Stewart Jul 20 '18 at 18:03
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You want hydraulic concrete.

Hydraulic concrete is a concrete that will bond to other surfaces when wet, and cure when wet. It can even be used underwater.

This page will give some guidance on how to apply.

Given the nature of hydraulic cement I'm thinking that your best bet is - in a dry place, build something that you can put in place to divert the water. Test it by "dry" (haha) fitting it against the spring (if thats the word), and once you're satisfied that it will divert the water properly once sealed, clean the wet space (Pressure washer, lose the moss and stuff) then seal in your diverter system with the hydraulic cement.

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Portland cement, the active ingredient in concrete and one of the active ingredients in cement/sand blends that masons use to lay bricks and more, will cure in the presence of water, even if completely submerged.

It will not “glue” to itself. Any bond that concrete has with a neighboring material (even more concrete) is purely mechanical.

If you are going to cast in place a concrete channel or curb to divert water, I would recommend drilling some holes in the existing slab, setting rebar into them with epoxy, and wire-tying to these vertical pieces of rebar some more pieces that will run horizontally inside the length of your casting.

If you are going to lay brick, I recommend roughing up the surface of the slab really well in the area you intend to lay on with a hammer. You have to take some chips out of the surface and expose some raw and rough concrete that the cement can bond to. The more the better.

  • Thanks Paul. So when you say the bond is purely mechanical, you mean the bond is not waterproof, right? I appreciate the rebar will make the structure stronger, but will it improve the waterproofing? In the answer below, someone recommends hydraulic cement. Im hoping this would make a waterproof bond with a neighbouring material - any experience of that? – Luke Smith Jul 23 '18 at 7:01
  • I don’t mean that at all. I mean that the bond is mechanical as opposed to chemical. The rebar has nothing to do with “waterproofing” and is needed to bond your new casting to your existing slab. Concrete is NOT waterproof, under any circumstances. It will hold water, but water also migrates through it slowly. It is okay for concrete to be wet all the time, it may even strengthen it over time. You can build a good channel to divert water out of it. I don’t know anything about “hydraulic concrete”. ALL concrete will cure to full hardness in wet conditions, even when fully submerged. – paul Jul 23 '18 at 20:59
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You can’t STOP the water, you can only CONTROL it.

You have water coming in from all sorts of places: 1) from above grade embankment, 2) from surface water, and 3) from sub-surface water.

I recommend you install a 4” rigid (don’t use the coiled perf pipe) perf pipe drain around the perimeter of your garage and on top of your existing slab. Then install a 6” layer of round drainrock (3/4”-1 1/2”) completely across the entire slab and encase the perf pipe. Then install a new 6” reinforced concrete slab on top of the drainrock and drainpipe. The perf pipe should be extended away from your garage using a 4” SOLID rigid pipe to a drainage swale.

The perf pipe and drainrock will collect any moisture coming from above or below the slab. Your new slab and garage will remain dry. (Btw, don’t connect any roof drains into this pipe. You don’t want a heavy storm to backup under your slab.)

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