Ahh spring is in the air! Even though it's still officialy winter, we in southern Calif. have it nice in that February here is like spring in the rest of the country. Having said that, I love to be outside and start the gardening and upgrading/maintaining previous projects. Being a concrete artist, I like making new projects with concrete and have included two new tree ring segments for this instructable that I have made recently to enclose two new avocado trees. A prior instructable: http://www.instructables.com/id/How-To-Make-Concrete-Tree-Rings/
shows the complete process of making tree rings. Pictures of other art projects are included in the final step.
Step 1: Finished Products Look Like this:
I planted two new avocado trees and one lemon tree. I had rings in place for other trees that didn't make it, so needed to make new segments for the new trees.
Step 2: Gather Supplies and Get Started.
To make tree ring segments, you need concrete, forms, a few tools, water, mixing container, etc. Later on, I use a hotwire machine to cut my letters out of styrofoam, and then use glue to secure them in the form prior to pouring the concrete mixture.
Step 3: Form Making
Shown here is the form I used for my segments. Basically, it is made of wood, cut out of a piece of two by six for the sides, and a piece of plywood for the bottom. I made a template out of cardboard by making two arcs, one at 36 inches, and the other 4 inches narrower, or 32 inches. I divided a 36 inch circle into 6 equal parts and used that dimension for the length of the form. On the inside of the form, I cut some thin strips of softwood and made a wavy design on them, cut them out with the bandsaw and glued and nailed them into the sides of the form. Before pouring, the form is coated with a thin coat of oil, and I used regular cooking oil.
Step 4: Cut Letters Out of Styrofoam
I go into my word processor, select a font of the appropriate size, and print out the word(s) I need. Then the letters are cut out with scissors and glued onto pieces of black stryrofoam, the type that comes in meat trays that you buy at the grocer's. For this instructable, I am showing "lemon" as my words for the form. I had completed "avocado" previously but did not take pictures of that. If you are interested in the hotwire machine, Mighty Goliath, see this instructable: http://www.instructables.com/id/Making-The-Mighty-Goliath-Hotwire-Machine/
Step 5: Glue Letters Into Bottom of Form
I place the letters in the form and line them up as best I can. I use a mirror to check my alignment, and when satisfied, I outline the letters with a pencil or sharpie marker. That way, when I glue them, it is easy to replace them in the proper place. I have found a tacky glue works best for this type of application.
Step 6: After A Few Hours Drying Time, It's Time to Mix Cement.
Using the ready mix as shown, I mix up one batch at a time to fill the form with. To make the right amount, I have learned from experience that it takes 6 cans of cement and 2 cups of water. The can used is a 14.5 oz. soup can. Make a fluid mixture, but not overly wet as the finished form won't be as strong if too much water is added. If desired, colorant can be added to the water prior to mixing. I found that one tablespoon is sufficient to color one segment.
Step 7: Fill Form With Mixture
Scoop several trowel fulls of cement into the form on top of the letters. When form is about half full, I shake the form and cement mixture back and forth several times to help the cement settle around letters correctly. Also, lifting form and tapping on counter top helps to get any air bubbles out and flow around the letters.
Step 8: Set Aside and Let Cure
No hard and fast rule here, but I wait a few days to remove finished product from form. I have taken them out at 24 hours, but it is better to wait longer, I think. Either way, you don't want to break the piece so take care in "demolding" process.
Step 9: Remove Cured Segment From Form
My form has cured enough so that when inverted, the segments more or less just fall out. Do this over a work bench so that you don't drop them, they will break! If the form is new, it may need to be unscrewed to loosen the sides from the finished segment. Completed "Lemon" added to instructable on 2/21.
Step 10: Place New Segments Around Trees
This is how the completed project appears in my yard and garden. These segments are just one of many things I have made out of concrete, and I have included a few pictures to show other possibilities. Enjoy!