Concrete Coffee Table

Incredible

Thanks for the comments everyone! If anyone is thinking about it, try it! It's way easier than I thought it would be. I'll post an update when we do the next one.

OK finished the shelf up.

Flat bar across the legs for the supports.

Cut and finished a few pieces of mahogany. Flat bar across the bottom to hold them together and keep the spacing.

My legs weren't perfectly located, so I had to measure a milion times to make sure my cut was going to be in the right spot to drop over the flat bar supports. Not square to the shelf... Used a router with a fly cutter to cut the slot.

Wet sanded the finish into the top with 400 grit. Works awesome using the oil to sand with. And done! Slots were in the right spots! I used a 1/4" fly cutter, with 3/16 flat bar, so I had a wiggle room but it fit perfect. Bad picture...

love that, well done!

Number 2 in the works. For a coworker, Its a fire table, we built a burner to go in the center, and it will be on his patio. propane firepit built into table... 40x40 table.

Much thinner this time, and we did our own mix. Its 1.25" thick, lots of fibermesh, no steel, and 50/50 mix of sand and portland.

Um, couple things. When designing your mixes any amount of rock will lower the amount of Portland you need for a certain strength. Each small particle of sand or rock needs to be coated with Portland. The more "fines" you have, the more Portland you need. Also, different limestones out there will have different hardness. Harder rock, stronger concrete.

You can easily get a smooth finish on thin concrete using "89" rock. "89" being rocks that fall through the screening process through the 8 and 9 sizes mixed together. About 3/8" to 3/4". The other popular mix for concrete is "57", 5 to 7 on the screening. 3/4" to 1 1/4" IIRC.

Be careful with the burner location, direct flame on concrete and it can explode.

jgrewe wrote: Um, couple things. When designing your mixes any amount of rock will lower the amount of Portland you need for a certain strength. Each small particle of sand or rock needs to be coated with Portland. The more "fines" you have, the more Portland you need. Also, different limestones out there will have different hardness. Harder rock, stronger concrete. You can easily get a smooth finish on thin concrete using "89" rock. "89" being rocks that fall through the screening process through the 8 and 9 sizes mixed together. About 3/8" to 3/4". The other popular mix for concrete is "57", 5 to 7 on the screening. 3/4" to 1 1/4" IIRC. Be careful with the burner location, direct flame on concrete and it can explode.

Dualy noted. We used a mix that was common in concrete tables. They did use csa when the temp was lower, but we tried without. If it doesn't work we will try again.

I stood on my table that used bagged mix, no breakage yet! We are trying to go thin though.

Stripped it this morning. Seems strong, but time will tell. Definately lighter than my top. I can pick it up by myself. Probably ~150lbs for a 40x40 top.

Stood on #2 after 5 days cure time. Did Not break!

Practicing making lips. I need an overhang on my counter top. It was a pain in the ass to do. #3 is 1" thick, with 1" lips on the edges. Same mix as #2. I will do an enclosed form next time I think, too hard to keep the mud in the lip and vibrate it.