What to do with new Concrete?

Bigboyskioti · Oct 21, 2007

Ok I posted a thread about the old blacktop drive being replaced with new concrete about 3 weeks ago. Now that it's completed, I have a new problem. I had them pour a pad (42' x 40') going over to the shed/barn. After a rain storm the other night I've noticed that some of the fill has moved and left a void under a small section. It's only about 4 to 5 feet wide by 20" under the pad. I know concrete will span that distance but it's on the edge. Do you guys have any ideas on how to fix this? I know I can put dirt back under there but I feel it will just keep getting worse. What about putting more concrete in the void? Any thoughts?

Mitch

rexcramer · Oct 21, 2007

you could fill the void with stone crete and then fix your drainage problem

machmeter62 · Oct 22, 2007

Bigboyskioti said:
Ok I posted a thread about the old blacktop drive being replaced with new concrete about 3 weeks ago. Now that it's completed, I have a new problem. I had them pour a pad (42' x 40') going over to the shed/barn. After a rain storm the other night I've noticed that some of the fill has moved and left a void under a small section. It's only about 4 to 5 feet wide by 20" under the pad. I know concrete will span that distance but it's on the edge. Do you guys have any ideas on how to fix this? I know I can put dirt back under there but I feel it will just keep getting worse. What about putting more concrete in the void? Any thoughts?

Mitch

: I would build a small retaining wall with pressure treated 4"x 4" posts and 2"x 6"s: leave enough room for filling it with "fill sand;" then re-watering it to get 100% compaction, but concrete may work too, but more difficult and expensive also?

Egon · Oct 22, 2007

As stated, you will need a drainage plan before fixing the void under the concrete.

I'd try and mix some no slump concrete and then try and pack/tamp it in under the new concrete. The important part here is to get the void filled and packed in solid.

Bigboyskioti · Oct 22, 2007

Thanks for the replies. The problem here is that the guy thought he was doing me a favor by pouring a wider pad. However he shouldn't have poured over the fill. The fill was just placed there a week before he poured. It's only about a foot of fill where I'm having the problem and I've thought about just digging down to solid ground and filling it back up with sakrete, can't get a mixer up to it now. I just wanted to hear what you guys had to say, I put alot of trust in what some of you say.

Thanks Mitch

Egon · Oct 22, 2007

If you are using Sackcrete get some Portland and add a shovel full to each bag for a little better strength.

For those areas that are under and back of the concrete pad mix sackcrete with just enough water so it does not run so you can tamp it in under the existing pad. This should help avoid any voids.

Bigboyskioti · Oct 22, 2007

Great idea... Even though I knew that I had forgotten about using portlad! I found my real problem though. I live on a hillside. The pad is acting as a dam during a rain. And the water that used to flow through the gravel is now puddleing on the uphill side. It's then seeping through and taking the dirt with it. I saw this happening this afternoon during a rain. so now I have to fix that problem! Might be a good time to try and talk the boss into letting me get that backhoe for the kioti. All I have to do is justify the 6 to 8 grand......

ToadHill · Oct 24, 2007

Cut a trench above the pad with one end about 5 ft from the pad and the other end 3 ft from the pad and extending about 6 ft past the side of the pad. You can plant it with grass or better yet, use 4" plastic pipe in the bottom. Cover the pipe with landscape fabric and fill the trench with stone.
The water running down the hill will hit the stone trench and flow into it and not under the pad. If you extend the 4" pipe far enough from the pad, the water will come out and run down the hill away from any problem areas.

blueriver · Oct 24, 2007

You will have to re route the water and fill in under the slab. Keep in mind no matter what type of fill you use other than a solid concrete material there is no way to pack it solid under the exsisting slab! Dirt/sand/gravel/clay all of those types will naturally settle.

I would (after the drainage is fixed) form outside the area that needs fill, and fill under the slab with more concrete, keep the outside form the same height as the original slab and allow the concrete to roll under the slab.

Good luck with your project!

Todd