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kleinisfijn t1_j657474 wrote

Try looking for concrete bonding primer, that's what you'll need to make sure it bonds well with the existing subfloor.

Forming can be done by anything that holds the concrete and doesn't absorb too much water. A couple pieces of wood will do fine most of the time for small jobs. If you have some melamine coated particle board which you can rip into strips it will work even better. You can use some cheap caulk to make sure the forms don't leak.

Normally you can walk on the concrete in about a day. However, it takes about a week before you can put a heavy load on it, and a full month before it's fully cured. If you can put flooring on it depends on the amount of moisture in the concrete. You can test this by putting a piece of clear plastic on the floor. If it isn't wet on the bottom after a day, it's dry enough.

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babypocketsquid OP t1_j65aqgf wrote

Do we need to drill holes throughout the 4x6 area so that the concrete has something to set itself into? I'm thinking 4 holes about 2-4" inches deep to prevent movement or would the bonding primer do that?

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kleinisfijn t1_j65ccvo wrote

It certainly wouldn't hurt to drill a couple of holes and run in a couple of tapcon concrete anchors. If you leave them sticking out a bit they'll act as pieces of rebar linking everything together.

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babypocketsquid OP t1_j69q5co wrote

What about grinding down the uneven surface? Given I'm going to be filling the area roughly 1-2" deep, does it matter if the surface is relatively ground down to an even level?

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