Have you ever wanted to create your own free-formed concrete bowl? Surprisingly, you can create a six foot long by four foot wide by two foot deep bowl with relative ease. I estimate that creating one will take you several days and roughly $300 to complete depending on what supplies you may already have available. Here are the basic instructions:
In order to complete this project you will need to round up the following items; a metal coffee can that has had its ends removed and has been cut in half, old blankets, a wooden float and a wooden plank that can support your body weight. You will also need a pointed trowel, a shovel, a role of chicken wire, 12 bricks or rocks that are 2 inches tall, 10 inch long wooden stakes and a wheel barrel. Other items that you should have include a pair of scissors, a garden hose and a water source to mix the concrete and a roll of black plastic sheeting. You should be able to find most of those items at your local hardware store. You'll also want to have an old car tire, a rubber mallet, a pair of wire snips, a tape measure, a pencil or black marker, a pair of work gloves and bags of concrete. In most instances, you will want to purchase concrete that contains coarse, aggregate gravel that has 6% air entrainment and a maximum diameter of one inch. Those living in areas with mild winters may opt to use concrete with a 4% air entrainment. The size and type of the gravel and the air entrainment levels are crucial because using the wrong ones can cause the formation of cracks. If you are unsure of what type of concrete mix to use in your area, it is best to seek the advice of a local contractor.
Digging the Hole
Begin by excavating the hole. You will need to pay particular attention to the slope of the hole because an improper slope will cause irreversible problems during the concrete pouring phase. If the slope is not properly planned, it will cause the concrete to run off the sides of the hole and pool into the center leaving you with nothing but a big, expensive mess. In a bowl the size I am suggesting, a slope of 70 degrees or less tends to work best. I wouldn't recommend going over 70 degrees. If you are sticking with the size bowl I suggested, you will need to dig a hole 28 inches deep, four feet wide and six feet long with and an extra four inches cleared on all sides for the concrete coping.
Preparing the Hole
Once you have finished with the excavation, grab an old car tire and use it to compact the dirt in and around the hole. Proceed by taking the chicken wire and molding it into a bowl shape that matches the hole you have dug. The edges of the wire form should come close to the rim of your bowl but not exceed it otherwise you'll mess up your concrete coping. Temporarily remove the wire frame and set it aside. Continue by placing a dozen two inch tall bricks inside the hole one foot apart from each other. If you don't have bricks, rocks will do. The bricks will serve as a support system for the wire frame.
Next, use a piece of black plastic sheeting to completely cover the hole's edges and allow the plastic to extend one foot down the sides of the hole. If you don't have sheeting, heavy duty shower curtains cut into pieces will suffice. The plastic around the edges is where your concrete coping is eventually going to go. Once the plastic sheeting is in place, lower the wire frame down onto the bricks. Continue by measuring and marking off one foot intervals between the openings in the wire form. Take 10 inch long wooden stakes and hammer one into the ground at each interval. I estimate that you'll need eight to 10 stakes. Once the wooden stakes are in place you will want to measure each stake from the ground up. Make a dark hash mark on each one at the four inch mark. The marks are designed to work as a depth guide during the concrete pouring process.
Preparing the Concrete
Prepare the concrete but keep in mind that it should have a minimum slump of 4 inches. Concrete with less than a four inch slump would be too inflexible and more than 6 inches of slump would be too fluid. Before slowly pouring the concrete into the hole, place a wooden plank that is strong and wide enough to hold your body weight across the width of the hole. The purpose of the plank is to give you a place to stand while you are working on the interior of the bowl.
Pouring the Concrete
When you are pouring the concrete be careful not to unseat the wire frame or let it sink below the two inch level of the bricks. You will want to fill the center of the bowl up to the four inch depth mark. Once you reach the four inch depth mark, remove the stakes. Use a wood float to smooth the inside of the bowl. Continue by adding a layer of concrete on top of the plastic that rims the edge of your bowl. Take the half a coffee can and use it, along with a pointed trowel, to shape your concrete coping.
Finishing the Bowl
After the bowl is complete, cover it with plastic and let it sit for one hour. Reexamine the bowl and if the concrete's surface is water free, go back over it with a trowel to smooth out any rough edges. Repeat this procedure until you can touch the bowl's surface without leaving an impression with your hand. Next, place a wet, old blanket into the bowl and leave it there until the concrete cures. Keep in mind that the blanket needs to remain damp until the concrete cures. Failure to do this could result in hairline cracks to form throughout your bowl. Once the concrete cures, remove the blanket and trim off any excess plastic that may exist around the concrete coping. Your bowl is now ready for shredding.
My children are skaters and I have a history of completing DIY projects.
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