Step 1: Materials
1. Four 8' 2x4's
2. Three 8' 1.5" plastic strips
3. Two 8' 1x4's
4. Three 8' 1x2's
5. Two 80lb bags of Quickcrete 5000
6. One tube of Liquid Nails
7. One bottle of concrete charcoal color additive
8. One sheet of Galvanized Mesh
9. One 4x8 board with white painted surface ( got this for a fraction of the price because it was scuffed up)
Items that I later found out I needed:
One more bag of concrete
More reinforcement (I used some old speaker wire conduit)
Tools I will use:
1. Cordless Drill
2. Circular Saw
3. Orbital Sander
4. Reciprocating Saw
6. 5 Gallon Bucket
8. Stainless Steel Screws
9. Tin Snips
Step 2: Location Decision and Allowable Space
Funny story: I once built a picnic table in the loft of our barn. It was the perfect place to work. Clean, dry and shaded. The table turned out perfect. It was well built and beautiful, but... well it was too big to get out of the loft. So now at our farm, we will always have a place to sit in the loft of the barn.
Step 3: Table Frame
Now that the form was constructed, it was time to add the reinforcements and anchors. I cut the galvanized mesh to best fit the space allotted. Next, I needed to add some sort of stiffener much like re-bar but with out all the extra weight. What I ended up using was conduit used to hide/route speaker wires. I removed the metal strip on the back side of the conduit which formed a trough that concrete could fill and provide added strength to the table. The conduit was light weight and easy to work with as seen in the photos. I was able to cut the conduit and bend down the cut section to allow for the conduit X to be on the same plane. A drill was used to drill holes along the conduit, and screws were added to secure everything to the table's frame. The anchors were also added to the table top by screwing the stainless steel screws in various locations on the table top and into the wooden frame below. About an inch of the heads were left exposed to ensure the concrete had something to form around and would be securely anchored to the tabletop without the fear of it sliding off. Now that the table top form was complete, it was time to add the legs.
Step 4: Table Legs
Step 5: Prepping for the Pour
Before pouring, all areas where concrete or liquids could escape must be sealed up. I used a fast dry calk to fill in around the form to ensure it was all water tight. I also moved the table into a shady level area in my backyard where I could pour the concrete and not worry about the sun drying everything out too fast. A level place to set the table will make the finishing work much easier because I don't have to worry about the concrete flowing to the low end. Now lets get dirty pouring that concrete.
Note: I also spray painted the legs during this step.
Step 6: The Pour
Volume (Length x Width x Height) 0.08568 cubic yards or 2.31255 cubic feet
Then subtract a little volume for all of the metal reinforcement.
One 80lb bag of concrete is 1 cubic ft.
Expected concrete top weight not including reinforcements ~ 185lb
Since one 80lb bag of concrete is one cubic foot, this means I would use just over 2 bags of concrete, right? Well not exactly, once I started to pour the mix, the center of the table started to sag a bit. I applied a cut piece of 2x4 under the table, but I was unable to totally fix the issue. I ended up using all three bags, so the table is a bit heavier than I initially planned. About 240lb for the top plus say another 50-60lb for the rest of the table. So my game table is expected to be a whopping 300lb.
Other than that little hickup the pour was pretty straightforward. I used a Rubbermaid trash can to mix the bags of concrete. First, I added water to the bucket then a little concrete mix and mixed. I did this process over and over until all three bags were mixed. I did this all at once so that when I added my color additive the final mix color would be uniform. I added the color additive periodically while mixing to help the color to be evenly distributed throughout the mixture. I will admit mixing 3 bags of concrete with a shovel in a trash can was not the easiest nor the best approach, I was really straining to mix the concrete while trying to keep moisture level down. By keeping the water levels down, the concrete has less to shrink and in turn less cracking potential. The drawback to using less water is that the concrete mix is harder to work.
After the mixing was completed, I used the shovel to move the mixture onto the table. I placed concrete evenly across the table and smoothed it with the shovel spreading it out. Once all the concrete mixture was on the table, I took my float and spread it out as close to level as possible. Next, I took a 2x4 and worked it over the table in a side to side motion leveling off the table even more. I also took a hammer and tapped all around the form to try and remove bubbles. Now that everything was level, it was time to smooth the tabletop with the float. This takes a steady hand and patience. Note: Make sure you do not wipe off the liquid that pools to the top of the mixture this helps to move your float around and is really important in the curing process.
Safety: Concrete is caustic and may cause burn to the skin. All concrete contains alkalies that react with organic matter. Length of exposure and presence of moisture will determine the degree of attack on the skin. The use of gloves is a good idea, but if repeated contact with the skin is made the area should be cleaned off with towels or rags. Continue to wipe off and dry areas of contact throughout the working period, avoid washing areas multiple times as this can worsen the reaction with the skin. Once the handling of concrete is complete areas of contact should be washed with water or diluted vinegar until the soapy feeling is gone.
Step 7: Curing
Once the concrete is poured, it needs to properly cure so that it reaches its maximum strength. For best results, the concrete needs to cure for a full 28 days. Over this 28 day period, it needs to continually be wetted down, so every morning and afternoon I gently sprayed down the table with a water hose. When I would do this, everyone could actually see and hear the table sucking in the water.
Note: I also sanded down the sharp edges during this step as well as lightly sanding the top surface. I did this by hand using 60, 80 and 120 grit sandpaper.
Step 8: Conclusion
The total cost of this table was under $100. This is not too bad since it is an extremely sturdy table and was a fun project to do with my son. He seems to think I really made the table especially for him to play with his cars. My friend and I have relocated the table to our Florida room. In the process of putting it in the room an edge was slightly damaged, but nothing to major. The table was really difficult to move due to its size and extreme weight, but we managed to get it in. I am still spraying down the table everyday, but I am now using a spray bottle to wet it down. Once it has fully cured, I will apply a sealer and wax the surface so that it is more comfortable to play on.
Things to do in the future...
My next concrete project will involve the use of wood fibers to increase strength and minimize the chances for cracking. I would also like to try a reverse form, where the concrete slab is flipped over after curing and the bottom becomes the top of the table. The bottom of my game table looks amazingly smooth, and I think that would be the best path for trying to make kitchen counter tops. I would also like to entertain the idea of creating a concrete mixture from scratch and use materials that will help to reduce the weight. In college I designed and built a concrete canoe from scratch for an American Society of Civil Engineers (ASCE) competition. The mixture used for the competition was very light and strong. Some of the more interesting materials used to help lower the weight included Glass bubbles and crushed oyster shells. I believe that the use of these different materials would make a table easier to move, but that will be for another day.
I hope everyone enjoyed this Instructable. It was a fun project to do with my son. My wife and I can't wait to invite the friends over and play a few rounds of Settlers of Catan on our new table!