Denver Decorative Concrete & Custom MasonryWhen pouring a concrete patio, how important is it to lay sand on the soil underneath the concrete?
My installer poured a brand new patio for me. He leveled the ground, meshed re-bar throughout, and then poured the concrete. I live in midwest where it can get quite cold. Will this hurt anything? Shouldn’t he have put a layer of sand or pebble underneath? Can you lay concrete on compacted dry soil?
The sand is not needed, compacted soil is fine.
The article http://landscaping.about.com/cs/hardscapefences1/ht/concrete_patio.htm suggests a layer of gravel.
For a house pad they usually put down what is called type 2 fill dirt. Gravel and sand, maybe other stuff also. This they compact down. You should put concrete down on fairly compacted ground. This is a patio so normally does not have to be the same standard as a house pad. The mesh rebar is what helps it from cracking and shifting. Cement to fully cure takes I think about thirty days but will reach suitable hardness in a day or two.
Sounds ok to me. Of course you need to keep moisture on it while it cures.
The sand or fine gravel is intended to keep the slab from cracking during the freeze thaw process. You see water expands when frozen which could push up from underneath and crack your expensive investment, the sand or gravel provides drainage so no freezing water is sitting under the concrete. Of course this would be less important in areas that never or rarely freeze, but if your investing a lot of time and expense in somthing it is better to do it right.
wouldnt have hurt to put a layer of stone , but if the pad moves as a whole it shouldnt present a problem…maybe the drainage under the patio is good enough as is…