New keyhole fire pit & grill

Hello fellow fire nerds. I am in the process of building a new keyhole fire pit in my backyard and would love to chat about it, get opinions, ideas, props, whatever! The closest approximation I can find is this: https://www.pinterest.cl/pin/477451997994860065/.

I am building mine out of concrete and am in the process of digging my hole. My planned external dimensions are 5' diameter with a 5'x3' extension for the charcoal grill end. I am shooting for about 14" above grade and 6" below. I plan on using it to grill obviously but am also planning on building a steel frame so I can do a rotisserie.

Has anyone done something similar? I was planning on lining the inside with firebrick and found a place I can get bricks for $2.50 each. When I called to order the brick, the sales guy said it was a waste of money and the bricks will wear out before the concrete. He said they were pretty porous and the freezing/thawing cycle in the winter would cause them to break. Anyone have any thoughts?

Any suggestions or ideas are also greatly appreciated. :-D

Here is the progress so far. Well, I did add gravel to the bottom but I haven't taken pictures yet. I got COVID and have been lazy for the past 6 days.



https://www.pinterest.com/gmascherino/firepit/

*Sorry for the multiple edits. I was trying to get the images right. I don't post to a lot of forums.

tom b said:

I like the looks of that pit and your progress so far :thumb:

But I have a serious question, what is the deep pit for? the fished pit in your OP doesn't look like it is deep like yours.

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I am going to put in a patio around my fire pit but I have to take the finished grade down about 7.5 inches at the top so the hole is pretty deep, about 17". I am going to pour the concrete 24" high so I can be 10" below the final grade. I am going that low so I will still have plenty of depth for my concrete patio pour. I will just have to add a bunch of gravel to bring the fire pit bottom up. The top of the pit will be 14" above my final grade.

My original post was just showing off the shape. I am building mine out of concrete and going to line it with firebrick. It is not going to be the same. That was just the best picture I could find to show the style.

Whumpa said:

About the only advice I can give you, and this comes from over 35 years in the concrete business. I was a cement mason. I noticed from your picture that it looks like you are using bagged concrete mix. If so, I highly recommend you bulk up your mix with more cement and more rock. Those bagged mixes have a high ratio of sand to rock and cement. Straight out of the bag the mix is not that strong. By bulking your mix you will gain strength and heat resistance. Also, not sure if you plan on putting rebar in, but highly recommend that also

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Thanks for the advice! I did buy 5 20' lengths of ⅜" rebar I will cut down for reinforcement. I plan to use some galvanized steel hardware cloth between the rebar.

I bought the 4,000 PSI high-strength concrete from Home Depot: https://www.homedepot.com/p/SAKRETE-80-lb-Gray-Concrete-Mix-65200390/100350291. Do you still recommend I add cement and rock? What ratio should I do?