Going Green with Reinforced Concrete Sculpting
by
Dr. John Daab CFE, CFC, AFC, RI, for Fine Art Registry®
(This is a second article in a series on sculpting with reinforced concrete. Read the first article, entitled Sculpting With Reinforced Concrete. Since the first article is more basic and gives an overview, it would be wise to read it before tackling this one which gets more into the nitty gritty.)
The Green Earth Approach
Normally, reinforced concrete sculpting creates an object utilizing sand, cement, water, steel and stones. The mass of the object is solely reinforced concrete. In this period of throwing out the old and creating the new, those demolished items add another garbage dump to an already crowded earth filled with garbage and/or ultimately adds heat to the earth's environment when the material is incinerated. Instead of utilizing or recycling existing objects, citizens tend to demolish, remove, and throw away items which could have additional uses, be cost effective, decrease labor time, and help save environmental damage. Rather than always starting from scratch, sculptors may want to step back and see if a relationship exists between what they want to create and an existing structure or object. Instead of cutting a tree down to the ground, use the trunk as a sculptural platform; instead of demolishing and removing an object, recreate it by manipulating how it looks, and applying a new cover to it. My Black Elephant was a tree which became a nuisance, and ultimately another sculpture. Turn it, don't burn it.
Black Elephant, sculpture
The Current Project
When I moved into my current residence I installed a lamp post. After a while my lamp post looked like every other lamp post. I researched the web for something different but it could not be found. At that point I decided to create my own. At first I was going to remove my old one and create a totally new one made out of reinforced concrete. As I began to design, I also began to tally the steps involved and the costs. To remove my old lamp post, it would cost about $1,000; to install a new one, I would have to get a permit, hire a licensed electrician, and have the town sign off the new installation. This would add another $500 and much time dealing with inspectors. I would also have to add a new footing for the new post since the old one would have to be removed and a new one installed. Adding up my costs and time I began to think about other ways of installing the new post and came to the realization that by using the old post I would save at least $1,500 and much time. I decided that there was no need to remove; what I had to do is to come up with a design which would utilize the old and at the same time create the new. The answer was encapsulation. Basically I had to box my current lamp post with reinforced concrete. The box was a form used to pour concrete into so as to attain a given look. I chose the easiest and most available box which is a round reinforced cardboard tube 8 inches in diameter used for concrete column construction. These forms are readily available at any hardware store, and come in a host of diameter sizes. The question now was what was my new lamp post going to look like?
The Design: Write It Down
Reinforced concrete sculpting begins with a concept or vision in the mind. You have an idea, an amorphous vision in need of an identity or structure. Step one in your creation is to place the idea, no matter how unclear or ambiguous it is, on a piece of paper. Preferably the paper is in a bound book, since pull out pages can easily be lost. You may think that the image supplied to the page is finished or almost finished. Think again! In one of my sculptures which consisted of just two slabs of polished granite it took about 30 renderings to complete the final work. The more parts and steps to a given work, the more complex, more renderings and more time will result toward a final design. The work recently completed took about 20 designs but much time to complete the final details. During the actual pouring of the concrete a final adjustment had to be made on the four columns on the top. Originally, the pieces were plumb, and consisted of only three columns. The writing down of the design, in pencil, allows the artist to use an eraser to change his work in progress rather than a jackhammer.
Identify the materials, tools and equipment to be used
After many revisions to your original pencil concept drawing(s), you will feel somewhat comfortable in starting the actual physical work of your concrete sculpture. The actual work starts with securing the materials and tools to build the project. Remember from the first article in this series that concrete work has a time frame before it becomes too hard to work with. Its set time reaches a point whereby you cannot insert objects into it or smooth out its exterior. It is important to identify, write down and have at hand all the materials and equipment you will need to create your work. Reinforced concrete is not merciful to those unprepared.
In any reinforced concrete project, the materials, tools, and equipment needed are:
- Forms. From your design of the structure sizes of height, width and inserts will be identified.
-
Yokes and bracing materials. (The form selected in this design did not need them.) The horizontal pinned items are yokes. The two parallel pieces at a 30° angle are braces. (On my photo they seem to have blue paint markings on them.)
- Hammer.
- Inserts for the completed product. Wood sticking out from form and metal pieces on top of form.
- Shovel for mixing the concrete.
- Reinforcing material. (See wire mesh under F in photo of material set up).
- Screw gun for installing the inserts.
- Lantern for light bulb.
- Plastic to cover socket to receive bulb.
- Concrete mix.
- Wheelbarrow.
- Level.
- Water source to mix concrete and wash tools.
- Masking tape to protect finished products from concrete spillage.
- Pail.
- A gallon of concrete patch for concrete voids ("honeycombs"). A honeycomb results when the concrete is not vibrated sufficiently and appears as if the materials have not been mixed.
Set up of materials, for concrete sculpture
Set up of materials
-
Typical column form (extra in case of problem). Please note that the piece completing the form was cut from the piece shown which was the same size as E. The two dark horizontal lines seen in the photo below represent the break in the concrete form. After the concrete was poured to the top of the form with the protruding pieces of lumber (E), the smaller form was added to the top of the (E)
- Shovel.
- Pail for water.
- Screw gun.
-
The form with attached wood and metal imbeds (to be installed on top of sculpture).
- Wire mesh.
- Wheelbarrow with level and extra wood imbeds.
- Globe for lamp (on hand to make sure that it fits on top). Finished product should be tested by laying the globe over the light bulb connection and twirling it on the concrete so as to form a good fit while the concrete is still soft. The globe should be protected with masking tape to prevent the glass from touching the concrete to keep the glass clean. The concrete is hard to clean off once it has set.
- Bag of 5000 lb concrete mix.
Forming the Sculpture
The first step in the present construction is to install the wire mesh around the lamp post making sure that a one inch space exists between your form (the next step), and the mesh. If the mesh is too close to the form the concrete might not cover the mesh fully when it is poured. Instead of a smooth concrete structure you might end up with one where the mesh is visible in the surface of the finished concrete. Once the mesh is secured in place, the column form is installed by sliding it over the top of the existing lamp post until it rests on top of the footing. In the design of the structure you may want to have a clean smooth look or provide imbeds for contrasts and shadows. I used one quarter by two inch lumber screwed in the side of the form prior to installation to disrupt the smoothness of the finish. Do not try imbed installation after the form is in place since it is difficult to secure as the space in the form is so limited. (See item E in the illustration of set up of materials.) With the mesh and wood form installed you are ready to begin pouring your concrete.
Pouring Concrete
Since an existing light fixture socket was being used, a plastic bag was placed around it to prevent any concrete from falling onto it. Dump one bag of concrete mix into the wheelbarrow, and slowly mix in water. Make sure the temperatures are above freezing otherwise the concrete mass will not set properly. Since there is limited space between the post and the form, the concrete mix should be more liquid than solid. If the mix is too stiff it will not move toward the bottom of the form. The mix should appear as a hearty soup rather than a broth. As your mixture begins to resemble this soup, begin shoveling it into the form. After a few shovels the concrete should settle to the bottom of the form. Take your hammer and begin tapping the bottom of the form to ensure that the concrete is settling properly and touching the form. The tapping will dissolve any air bubbles preventing the concrete from settling. Continue mixing, dumping and tapping the form. At the top of each dump water will begin to appear. The presence of water indicates that the vibrating/tapping of the form is settling the concrete. As you reach the top of your sculpture refer to your design to make sure that all your imbeds are in place. In this project the design had four chrome pieces emerging from the top. There was no reason to install beforehand, they were inserted into the fresh concrete. If an insert had to be installed at the bottom of the form at this point the concrete would have been too hard to allow the insertion. The top concrete was still soft for insertion.
Protecting and Allowing the Concrete to Cure
The poured concrete should be allowed to set up/cure for about 3-4 days before removing the form. If the temperatures are expected to fall below freezing during the curing time span the work should be covered and heated using some type of space heater. The goal is to maintain temperatures above freezing. If for some reason the concrete top appears green, allow more time before removing the form. The concrete should appear grey. In extreme heat, and in the case of slab work exposed to the sun, to prevent premature cracking, wet blankets or a fine mist may be used. Normally water is not used. Remember that too much water in concrete weakens its structural integrity.
Stripping the Form
Remove the screws attached to the wood imbeds and begin peeling off the column form. Note that this form is a throw away form - it is not made to be used again. Start from the top where a point appears in the form. Begin to peel away the cardboard all the way to the bottom. If you have done a good job of tapping, the concrete exterior should be smooth without any "honeycombs" or missing concrete. If there are any honeycombs, use your concrete patch to fill them in. Remove your wood imbeds slowly so as not to chip the edges of the concrete.
The Result
Reinforced Concrete Sculpture Project, before and after
Summary Steps
- Examine if work can be recycled.
- Design it on paper and size it.
- Secure materials, tools and equipment near work.
- Install footing if necessary.
- Install reinforcing mesh or rebars if necessary.
- Place form with imbeds around rebar or mesh maintaining one inch clearance.
- Brace form if necessary.
- Protect any areas which may be damaged during the pour.
- Pour concrete into form gently tapping the form while pouring.
- Install imbeds on top.
- Protect and allow curing to take place.
- Remove any screws or nails to allow for stripping.
- Strip forms.
- Patch any voids.
Read these related Fine Art Registry® articles:
— by Dr. John Daab CFE, CFC, AFC, RI
| May 15, 2009 |
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