Correct cement mix for ..

Don't know the terminology; *sticking* maybe? I am making a ac hole in wall smaller so I pour the bottom and did the sides. now I need to do the *roof/ceiling* of the hole.. it has eight inch blocks..some spaces to fill in em. What is the correct mix so when I apply the cement, gravity doesn't win all the time. Someone told me cement, lime and sand will do it..I wasn't using lime so that may be the case. if so what are the proportions and/or any other ideas? thanks req
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reqluq wrote:

How to do it: * Buy the premixed concrete. * Add water until it's the consistency of peanut butter or thicker. * Apply the concrete to the top of the hole. * Put a wood form underneath to keep it from falling down.
Pertinent question: Why do you need to fill in the top? I'd just fasten the junction box in the wall and leave it at that. (You do know that a junction box is required, don't you?) If I needed insulation, I'd shoot some expanding foam around it.
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No junction box. it's a wall unit air condition, it slides right in the hole. You say: apply concrete to top of hole, then put wood to keep it from falling down..if it hasn't fallen down before I put the wood I don't need to put the wood. req

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reqluq wrote:

I'm sorry. I thought you were making an opening for an AC (alternating current) junction box opening smaller. Chuckles all round. :-) In that case, you would have forced the concrete into the top of the hole, then put in a piece of wood to keep it from slowly sagging. The small amount of very thick concrete would have stayed in place long enough to get some support under it.
On topic: Build a wooden form. Somehow (how I don't know) get the concrete into the form on top of the wood. This sounds difficult.
I suggest you just insulate the inside of your concrete blocks with expandable foam, then add wood trim to make the opening the right size for your air conditioner. Finish off with some door casing to hide the edges of the opening.
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How about installing a form board across the top of the hole, drilling holes into the block "voids", pouring concrete into those holes, then patching the holes?

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Erik Dillenkofer wrote:

Sounds like a plan to me.
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Excellent! req

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On Tue, 21 Oct 2008 02:50:39 +0000 (UTC), "SteveBell"

Another way would be to frame the bottom piece, and one side. Then fill that space with a very dry mix, and slap on the other side when the space is filled. A couple of big C clamps could be used to hold the side on as the mix set.
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In some cases I have drilled small holes with masonary drill bit (rotary hammer drill) in the concrete hole area and attached any metal screws and hardware cloth to give concrete a "web" like mesh to hold concrete....... jloomis

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Hey this gives me an idea: stell mesh that they use to put concrete on wood or join corners so they don't crack. then paste away thanks for the suggestions folks req

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Dry pack is the term we use.......Hardly any water in the concrete mix.... Push it into the mesh.......dont worry about finishing it smooth. do a rough job and come back later with a creme concrete and touch it up. jloomis

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