42" Pompeii in S. Louisiana

[stonecutter]

Re: 42" Pompeii in S. Louisiana

Looks nice Kurt ..but I think the form was pulled too quick....I usually wait at least three days. You should be able to mix up some slurry and build up the damaged edge.

[Gulf]

Re: 42" Pompeii in S. Louisiana

Looks great Kurt,
I like the form work you did. The pvc pipe was a clever idea. I would have been afraid to have pulled the forms that soon but they look very smooth to me. I guess you will be filling bug holes today.

[Kurtloup]

Re: 42" Pompeii in S. Louisiana

I just pulled the forms. It looks like it came out pretty good. On one side, the bottom edge crumbled in a spot. I think the mix was too dry in that area.

[Kurtloup]

Re: 42" Pompeii in S. Louisiana

Home Depot finally received the countertop mix I ordered so I poured the counter today. It took 7 bags. My idea of having about 1/8"-1/4" of a slope away from the oven didn't work out. The mix was too self leveling.

[stonecutter]

Re: 42" Pompeii in S. Louisiana

Yikes, just went to a big box website and that counter mix is $13 for an 80 lb bag. I would use the 5000 high strength and modify it myself with polymer or acrylic. That I have done before...and it works well.

[stonecutter]

Re: 42" Pompeii in S. Louisiana

If you think it will make any difference, I can pour it in two pieces. The first being the decorative cove over the bricks. After it sets up, I can pour the top.

Better off doing it in one shot... You will have the same concerns if you pour twice. Plus it's more work.

[stonecutter]

Re: 42" Pompeii in S. Louisiana

If you are using counter mix you can still use acrylic additive, it doesn't hurt the mix as long as you have the correct amount of water needed to properly hydrate the portland. If not, you should be good, but I have never used quickcrete mix before..I hear good things though.

Definitely do NOT put insulation board under the concrete. you need firm support under concrete and the board is subject to compression from the weight of the 'crete. Remember concrete is relatively weak in tensile strength..that's way reinforcement and graded aggregate are used.

[Kurtloup]

Re: 42" Pompeii in S. Louisiana

If you think it will make any difference, I can pour it in two pieces. The first being the decorative cove over the bricks. After it sets up, I can pour the top.

[Kurtloup]

Re: 42" Pompeii in S. Louisiana

Thanks for the tips. I ordered bags of Quikrete Countertop Mix. It has a super plasticizer additive added to the mix. I assume this is what you are referring to? So, I should add the plastic sheeting just over the brick and structural slab? I have extra insulating board so I planned to place it over the slab so I won't have to use as much countertop mix. Bad idea? The edge along the brick will be 6" thick with at least 3" being the countertop.

[stonecutter]

Re: 42" Pompeii in S. Louisiana

Sweet Kurt, looking forward to the finished product. I do have a couple things for you, maybe you are already going to do this but...

I wouldn't pour the concrete without an uncoupling layer..like sheet plastic. The different rates of expansion between the materials will crack the counter in a very short time. This layer will also serve as a crack isolator too, preventing the cold joint between your cmu and structural slab causing a crack to migrate up through the countertop.

Definitely use an acrylic or polymer additive to your mix, add about 10% of your volume of water. Great for reducing chances of shrink cracking.

Anyway, looking forward to seeing this.

[Kurtloup]

Re: 42" Pompeii in S. Louisiana

I began making the form for a pour in place concrete countertop this afternoon. I made a quarter round out of 4" PVC pipe. The rest of the form is melamine.

[Les]

Re: 42" Pompeii in S. Louisiana

I'll have the weight of a 2' clay flue (about 45 lbs.) and enough exterior brick to cover the flue supported by the arches.

That sounds a lot like my approach. I dropped some steel through the cores of the exterior brick. The concern isn't compressive, it's the side load. If you think it may be an issue you can address it when you get to that point - looking good!

[Kurtloup]

Re: 42" Pompeii in S. Louisiana

Steel up from the hearth into the vcrete? No. Rebar in the hearth, yes. I made the assumption that the vcrete has enough compressive strength to withstand any outward pushing of the arches when the exterior brick is laid next to the vcrete. The force will have to displace the exterior brick too. I'll have the weight of a 2' clay flue (about 45 lbs.) and enough exterior brick to cover the flue supported by the arches.

[Les]

Re: 42" Pompeii in S. Louisiana

Did you drop some steel into the hearth? I wouldn't expect a whole lot of shear strength from the vermiculite. May not be an issue, I have no clue of the load.

[Kurtloup]

Re: 42" Pompeii in S. Louisiana

Because I felt it would be easier to brick the roof with the support and it will add buttressing once I brick around it. I hope that makes sense.