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We were moving into a new house and the girlfriend hated our old Ikea coffee table, so we decided to make ourselves a new one. It's not made of pallet wood, so we're ok there, but we did use threaded pipe... Don't shoot us.

Parts:

- Melamine board for form making

- Dap/Silicone/crack sealer (DAP)

- 2 bags of concrete (Concrete)

- Poly fibres for concrete reinforcement

- 1" thick rigid styrofoam insulation (Rigid insulation)

- Threaded pipe fittings, 3/4" and 1/2" (Pipe Fittings)

- Threaded rod and nuts (Threaded Rod)

- Concrete sealer

- Sand paper

- Dust Masks

- Bucket for concrete mixing

Cost: The majority of the cost was in the threaded pipe fittings. They run close to $2 CAD each. We were fortunate enough to get a few things for free as well - Concrete sealer and poly fibres. Our total build cost was $160ish CAD but if we had to buy the sealer and fibres, we would have been about $200 CAD all in.

Dog: Gus had just been neutered when this picture was taken so he has his anti-licking shirt/onesie on. It is almost more ridiculous than a cone.

Step 1: Build a Form

We used Melamine for the form. The thin sheet on the bottom seemed like a better bet than a 3/4" piece simply due to the cost. We had a heavy board underneath it so it wouldn't be able to flex. The edges are 3/4" melamine.

You use melamine for it's smoothness. Any scratches, dents, blemishes on the form will show up on your finished concrete. If that's the look you're going for, good on ya. If you want smooth: go melamine.

After screwing the whole thing together, we sealed all the edges with Dap to ensure the corners would not leak.

If you look closely at the left "wall" of the form, you can see a pencil line. That line is at the 1/2" mark. In order to reduce the overall weight of the table, we decided to add rigid insulation to the core of the table. Remember how your parents used to have an empty jar or something similar in the toilet tank to take up space so you didn't use so much water? Well, this is the same idea. The insulation takes up the space that would normally be solid concrete, thus reducing the concrete volume used and reducing the overall weight.

Our total table thickness is 2": 1/2" Concrete 1" rigid insulation core 1/2" Concrete

The insulation is cut back about 2" from the long edges and 5-6" from the short edges. This gives us solidity around the whole table and a place to attach our legs directly into concrete and not into the insulation.

Step 2: Give It Some Legs!

While the dap dried, we put the legs together. We used 3/4" pipe for the vertical supports but reduced down to 1/2" for the horizontals. This saved us a bit of cash.

If you look closely, you can see the threaded rod and nuts sticking out of the flanges on the left side. These will embed directly into the concrete. More on that later.

Step 3: Call in the Reinforcements!

Again, in an effort to reduce weight, we opted to exclude re-bar or any other reinforcing metal. We went with poly fibres instead. A friend who works for a concrete company gave them to me. I didn't do any testing to see if it was stronger, but it hasn't crumbled yet. 3 months and counting!

Step 4: Pour It

Sorry, a bit of a jump ahead here we mixed and poured the concrete. My mix was a bit dry but it seemed to go in nicely. We followed the instructions on the bag but could have used more water. Pour 1/2" of concrete into the form, lay in the insulation, fill in the rest. We tried our best to smooth out the concrete, but our troweling skills aren't the greatest, but we like how it came out. A little rough around the edges

Step 5: Attaching the Legs

This is how the legs are attached to the table. I just used threaded rod and not bolts (as drawn). After we poured the concrete, we placed the legs on the wet concrete and pushed the rods in. They probably aren't gripping as well as we'd like, but they didn't really move after everything was dry, so we called it good. If they come out down the line, we'll just put glue into the holes where the rods were and then put the rods back in those holes and it shouldn't move again. But for now, the weight of the table is holding everything in place.

Step 6: Poured and Covered!

Sealing in the moisture is important so we laid some poly on top.

Step 7: Oooooo, Ahhhhh. Unboxed

We unwrapped it after an impatient 7 day cure. It came out of the form pretty well, but peeled a pit of the melamine paper off, which stuck to the table top. Hand sanding and a flap wheel attachment on my drill made quick work of that.

The sanding was taxing, but not terribly difficult. Especially since I just stood around taking pictures and not helping. All of the melamine remnants came off fairly easily.

Step 8: WE LANDED ON THE MOON!

We didn't get an absolutely flawless finish on the table top, but really, we didn't want it to be perfectly smooth. The pits and air bubble holes add texture and depth. We could have smoothed it out more by vibrating the concrete and having a wetter mix.

Step 9: Signed, Sealed, Delivered!

We were going to scratch our names into the bottom before it dried, but we waited too long. The nieces were on the driveway drawing with chalk so we decided to do the same. We signed the bottom with chalk and then sealed it in forever!

Step 10: Sealed and in Place

We sealed the table then added 4 coats of clear on top. Most of the pits and holes filled in a bit but there is still some texture. It's tough to see but it is really smooth! It looks at home in our place and Gus approves! Thanks for looking!

nice clean look- I like!
<p>Looks like a decent first build. I think you will find that the slab will crack when you start moving it around. The foam addition doesn't add strength and in fact weakens the slab.<br><br>I don't see a lot of aggregate in your tabletop. Quikrete makes a countertop mix that is high strength. The fiber material you added will not provide continuous support over any length. Adding wire mesh (at minimum) or small diameter rebar would have been much better.<br><br>I made an outdoor countertop using Z Counter Forms. It's 2&quot; thick and has a frame underneath. It was cast in place and the durarock bottom stays. Z Forms have some excellent how to videos.<br><br>Like you, I thought a wetter mix would work better. I was wrong. In fact, a drier mix is better and then use a palm sander on the forms to vibrate everything into place. Additives may help even though it may increase the cost.<br><br>In essence, you have two slabs with a foam sandwich in between. I'm not sure the minimum thickness for a table of this dimension from an engineering standpoint. I'm guessing you could have eliminated the foam, made it thinner, and used steel bar.<br><br>Either way, I like the industrial look. Hope it works out for you.</p>
<p>Thanks for the comments. We haven't experienced any problems with it yet. We wanted to maintain that thickness while minimizing the weight. We probably could have put in some steel lathe for support but in all honesty, it's likely overkill - as are the fibres. It's never really going to be carrying a lot of weight so we're not too worried about it breaking. </p><p>We also didn't vibrate the forms so that may have helped us.</p>
It's not that you will be sitting on the table or putting weight on it, the concrete brings its own weight.<br><br>&quot;For additional insurance against cracking, some countertop fabricators add tiny synthetic fibers to the countertop mix. These fibers, alone, will not provide structural reinforcement for concrete countertops, but they are effective at controlling shrinkage cracking. Contractors usually use them in combination with steel rebar or wire mesh.&quot;
<p>Well, no going back now lol. If it breaks, we'll deal with it.</p>
<p>If it breaks, accentuate that break. Get you some metal strapping and some sort of off color concrete caulk. Drill and bolt the strapping top and bottom and fill the void with the caulk. Will look even more industrial like in this link http://nextstar.ca/images1/wallrepair.jpg</p>
<p>On travertine they fill some of the voids with something, I wonder what that is because some of the tile I have it came loose and I'd like to refill it.</p>
<p>More than likely it's unsanded grout. The same they used for grouting the tile. Hopefully they left you some. If they didn't, try to find out what color they used. If you can't, it's okay. Find something that is close. Nobody will notice. Clean the voids well. Get as much debris out as you can. Using a small foam float. Mix up the grout in a pail and fill the voids. Be sure and use various angles as you float in the grout. Let it dry a little bit and wipe with a clean sponge and clear water. If you have some film leftover after it all dries, you can use an acidic tile cleaner to remove it. Go easy on the acid though. Less is more. If you have sealed travertine, you will need to reseal the portions.</p><p>Good luck.</p>
<p>That's a neat idea! thanks!</p>
<p>Understood. Just wanted to give a little advice from somebody who has worked with concrete and also done a similar build with a counter top. Looks great.</p>
<p>I appreciate it!</p>
<p>On the contrary, the poly fiber will add structural integrity, but not protect from flexural loading. The concept of adding &quot;fibers&quot; to increase structural integrity has been used since &quot;ancient times.&quot;</p><p>Great concept; I would suggest utilizing Lightweight Concrete mixtures as the aggregate is specifically engineered/mined for its lightweight properties. To avoid having to sand; if you use a concrete float (basically a metal trowel) to smooth the surfaces this will bring the liquid slurry to the top and create that smooth look you see on floor slabs.</p>
<p>Understood. I guess I should have clarified a little bit. I wouldn't pour anything like this without adding some structural component like rebar or at minimum mesh. I prefer bar although it seems like overkill but hey, why put the effort in without making it Tim Taylor proof? LOL</p>
<p>Thanks for the tips!</p>
<p>Is there any way to round the corners? Concrete could really hurt if you hit it with your foot or something. Would you just have to make a different mold?</p>
<p>My tile guy used a grinder with a stone wheel to shape my travertine tile around shower door, so he didn't have to buy the edge tile with the round edges. Harbor Freight has cheap grinders.</p>
<p>Wow! Thanks! Thanks all of you guys!!</p>
<p>Probably the easiest would be to get a block of wood that is twice the width and length of the radius that you want for the corner. Then drill a hole in the center of the block that has a diameter of twice the radius of the curve. Then you get four pieces of wood with the correct radius that you can tack into each corner.</p>
<p>The easiest way would be to make a different form. You might be able to grind it down after the fact, but it would be a lot of work and difficult to get all the corners to look the same.</p>
Very true.
If I were to round the corners, I would make 2 slat both the same length using formica countertop scrap.<br><br>I would place a slat at the center of the end aligned with the center of the slat and hot glue it in place. The ends of the slats would press up against the sides of the form. these ends can. Be pulled away from the end of the table along the side to adjust the corner.<br><br>When the perfect corner is found, makes the othe other 3 slat ends the same distance and hotglue in place.<br><br>It would make perfectly matching arcs.<br><br>Place rocks or sand behind the slats to keep them stable while pouring. (Also I wouldnt really use hot glue. But it should work.)
Wow! Thanks! You should make that into an Instructable!
<p>You could also just run a bead of caulk in the corner and smooth it out with your finger before you pour the concrete. I've seen the pros do it that way.</p>
<p>That's what was done here. It makes it a bit more rounded but nothing substantial.</p>
<p>If you get tired of the rough surface, I think you can mix some portland cement by itself and trowel it on top for a smooth shiny surface later on. There are trowels that have a round edge to make round corners while it's still wet.</p>
<p>Adding fiber to a concrete mix provides some tensile strength, but it doesn't replace rebar or welded wire fabric. If bar or mesh is used, placement is critical and should be 1&quot; clear from table top. As concrete cures, and it never stops curing, it shrinks and the edges want to curl up and deform into a smiley face configuration, exaggerated. That's where the steel reinf resist the tension from shrinkage. Controlling your curing process helps resist surface cracking too. A water soaked beach towel place atop the table would be a good idea for 24 hours. A lower compressive strength concrete mix, say 3000 psi, would be easier to work with and result in less cracking than a 4000 psi or higher mix. I doubt you're going to have a compression problem on a table top anyway, good luck.</p>
<p>Thanks for the tips!</p>
<p>That's my kind of furniture with the iron piping for the supports. Way to go!</p>
<p>Thanks! </p>
Kudos to the both of you! The design is one of a kind and exclusively yours. Inovative techniques and awsome finished industrial look. Keep it up!
<p>Thanks for the kind words!</p>
<p>Very good and thought provoking. Your's is done and you will see...</p><p>How about, like your method of attaching the top, you made short versions for the</p><p>feet, epoxy them in? A short piece of rod and a nut, make it look like it's bolted to the floor! Follow me?</p>
<p>I'm not sure I understand what you mean.. sorry!</p>
Before sealing it, I would have taken a tire, put a little stain on it and would have rolled it over the top. (Your place looks too nice for that though.)<br><br>With the tracks on top, people would always wonder if you just cut off a piece of your neighbor's driveway, or you are an environmentalist and reused torn up driveways.<br><br>Great thoughts!<br><br>Would spraying it down with water have work as well as sanding? I dunno.
<p>Haha I like that. Not in my house.. but I like it! I'm not sure if wet sanding would have helped. I've seen wet grinding for concrete so I assume it would help.</p>
<p>Interesting idea, but not an option for a house with little kids :)</p>
<p>Yeah, I was a bit nervous with my nieces running around, but thankfully, nobody bonked into it!</p>
<p>if you want a smoother finish, make the mix with more water. Once it's poured, use a wooden float &amp; gently smooth &amp; smooth &amp; smooth again. Basically play with the poured concrete - works a treat. This is a lovely instructable.</p>
<p>Thanks for the tip!</p>
<p>I love this--did you consider adding any color when you were pouring? I'd like to try it with different dye in smaller concrete batches before pouring... maybe even turn the top into a painting of sorts. Has anyone done something like that?</p>
<p>We wanted to keep the industrial look with the standard colour so we didn't explore anything like that. Would be cool for the next project though.</p>
<p>Thanks for sharing the project. My question is where did you find a girlfriend that was ok with the galvanized pipe fitting legs? ?</p>
<p>Um.. looks like black steel pipe + cast iron fittings?</p>
<p>Bonus for me... it was her idea!</p>
Hang on to her!
<p>This is really nice! I'd much rather have a table like this, it looks great and is harder to damage. :)</p>
<p>Depends on the concrete mix. </p><p>Do a slab with (weightwise) 3 parts cement, 20 parts sand and 2 parts water (just enough so there is no more dry powder after thorough mixing - excess water makes for soft concrete). The resulting mixture should seem not to hold together. If it easily holds together it's too wet. It will hold together very well, once cured, if compacted before starting to cure - see below.</p><p> Use something to shake up/vibrate the mold while pouring (for instance an orbital sander attached with screws or tape to the mold), and beat the conrete in with a piece of firewood or a brick or something similar, to remove all bubbles - if you prepare it pretty dry it won't flow to fill all gaps by itself. Then yes, the resulting slab will have no large pores and open bubbles and will be extremely strong.</p><p>A slab poured with a mix too wet will be soft, and easy to chip. A decently reinforced slab, at the size of a table and with no significant load to bear will not break, but a chipped coffee table is probably not what you want in your living room.</p>
<p>Great Advice!</p>
<p>Thanks! It is pretty tough!</p>
Would be cool to make a clear epoxy fill with some of that ten hour glow powder and fill in all the little holes in the top, sand it down level and then seal it in with a clear coat layer.

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