Quote:
Originally Posted by rfuerst911sc
1.I assume I should put down plastic in the freshly dug soil for a vapor barrier ?
2.Should I put any gravel on/under the plastic?
3.How much rebar should I use for an area aprox. 4 foot by 7 foot ?
4.Should high strength concrete be used or regular ?
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1. Wouldn't hurt. Make sure the soil is well compacted and level.
2. Wouldn't hurt, if you put it underneath the plastic. Of course, you'll want to go deeper then, which means you'll have to deal with some other issues, so maybe it's not worth it.
3. I'd use #4, doweled into the adjoining slab, on 12" centers each way. You'll likely have two layers, the bottom one needs to be 3'' off of the bottom of the excavation. The dowels will be above this, as your existing slab is not going to be 12'' thick. The dowels don't have to extend all the way across but I would so so, as it takes very little time and costs almost nothing. Rebar is so cheap, it's nearly free. Of course, I buy mine from a steel supplier, not Home Depot.
4. I'd use at least 4000psi. Around here, I can get that for $10/yard more than 3,000psi. Given your small quantity, that's almost free. 4000 high/early is even better and about as cheap. Use that and you get to play with your lift sooner. Most concrete suppliers have a mix they use for highway road patches that need to cure quickly. It's usually pretty good. Feel free to put a curing agent on top of the finished slab.
Make sure the bottom of the hole is well compacted and the moisture content of the soil is not too high or low. Concrete likes to sit on something stable.
JR