Introduction: Makng a Concrete Gecko (7.5m )
I was commissioned to produce a concrete model of a gecko for a new housing development.
I am a sculptor,working in wood, steel , bronze , plastics and concrete.
For this project, I did quite a bit of research into high strength mortar mixes ( no stone , just sand / cement )
Step 1: GECKO Underwoodisaurus Milii
First , catch a gecko. This fellow helped out for a bit. Then I made a maquette...
Step 2: Maquette
Carved in foam and coated in acrylic plaster and finishing cloth ( fine chopped strand mat )
sketching with 10 mm steel rod
Step 4: New Studio
Using a ring roller, building the body, welding intersections
Step 5: Sub Frame
Heavier steel for strength and to bond to slab.
Step 6: Internal Skin / Hessian /poly Foam Internal
I glued hessian to the inside of each half of the steel work. This was to provide a surface that could accept an internal spray-up of polyurethane foam.The purpose of this was to provide a firm surface to apply the glass and steel fibre reinforced mortar on the outside , through the layers of bird mesh.
Step 7: Reassembling the Two Halves and Chicken Wire Mesh Application
Chicken wire was stitched on to the steel rod armature. Cast concrete eyeballs fitted.
Step 8: Mortaring the 25 Mm Skin
The mortar mix was designed in consultation with a concrete engineer from Tasmania.
3 parts sand
1part Portland cement
10% Magnesium Oxide ( high early strength )
steel fibre reinforcing
glass fibre reinforcing
water reducing compound ( the strength of concrete is inversely proportional to the amount of water added or water-cement (w/c) ratio.
Step 9: After Curing, Acid Staining and Anti Graffiti Coating
I made 6 gum nuts in ferrocement also , to provide scale and to be used as casual seating.
Acid stain in various colours was worked into the surface and finally a coat of anti graf sealer that came from a firm called Gecko Coatings. It seemed appropriate...
Step 10: Leaving the Studio
Big test ! the gecko, weighing approx. one ton ( 1000kg ) was lifted out of the studio and trucked to its place in a playground. No cracking. The sub frame was anchored to the ground slab and a coating of rubber soft fall was put around .