Any concrete experts on board?

[michiganmushrooms]

I am in need of some free concrete advice.

I just finished laying a thin layer of portland cement on the floor of our mushroom house. I was so sick of little bits of mushroom and straw falling into the gravel and getting lost I just went ahead and started pouring.

This was an extremely amateur job, and I don't really care if it cracks a little bit. As long as it is easier to sweep and wash than gravel, which it will be as long as it doesn't crack up so much it turns to gravel.

So what I did was just pour the cement on top of our already well packed gravel and smooth it out as best I could, that is to say not very smooth. No re-bar, no wire mesh, just cement on gravel.

So what problems can I expect now? What kind of life-span will a shitty job like this have?

[ghettopalmetto]

I am in need of some free concrete advice.

I just finished laying a thin layer of portland cement on the floor of our mushroom house. I was so sick of little bits of mushroom and straw falling into the gravel and getting lost I just went ahead and started pouring.

This was an extremely amateur job, and I don't really care if it cracks a little bit. As long as it is easier to sweep and wash than gravel, which it will be as long as it doesn't crack up so much it turns to gravel.

So what I did was just pour the cement on top of our already well packed gravel and smooth it out as best I could, that is to say not very smooth. No re-bar, no wire mesh, just cement on gravel.

So what problems can I expect now? What kind of life-span will a shitty job like this have?

How thick was the slab you poured? What was your water-cement ratio? What are the dimensions of the slab? What's the spacing of your control joints? What are the conditions at the slab edges?

[ccbatson]

Finally, a topic on which Ghettopalmetto and I agree...concrete.

[michiganmushrooms]

It was very thin, as thin as I could possibly get it so I wouldn't use as much. Maybe between 2 inches and half an inch , it is not uniformly done.

I just eyed up the ratio, couldn't even guess. It cured well overnight though..

The dimensions were roughly 20x40

Control joints?... ahh no.

Some of the edges are cracking a bit already if that's what you mean. Mostly they edges run right up against the baseboard of the greenhouse, we left a small section of the gravel uncovered as a drainage area.

[ccbatson]

It doesn't sound good for that piece of concrete...expansion joints are critical and that is just one error evident.

[ghettopalmetto]

It was very thin, as thin as I could possibly get it so I wouldn't use as much. Maybe between 2 inches and half an inch , it is not uniformly done.

I just eyed up the ratio, couldn't even guess. It cured well overnight though..

The dimensions were roughly 20x40

Control joints?... ahh no.

Some of the edges are cracking a bit already if that's what you mean. Mostly they edges run right up against the baseboard of the greenhouse, we left a small section of the gravel uncovered as a drainage area.

What you essentially have is known as a "topping" slab, used for floor finishes, but not given any consideration for structural integrity. Unfortunately, you should not expect your slab to last long. Your slab is too thin to have much in the way of rigidity [[absent any stiffness of whatever is supporting it below), and will be very susceptible to cracking. The *minimum* I've ever specified a slab was 2" thick, and that was where the bottom of a ramp keys into a floor slab. The varying thickness [[up to 400% variance) will play hell when the slab expands and contracts, especially since it's in a greenhouse, which has much greater temperature extremes than a typical inhabited space. You should cut at least one control joint to divide your 20' x 40' slab into two squares, but the limited thickness of your slab could prevent you from cutting an adequate joint.

[ccbatson]

Dang Ghetto...you do know your concrete.