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 )

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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 )

Step 3:

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 )

Fly ash

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 .

Concrete & Casting Contest

Second Prize in the
Concrete & Casting Contest

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    46 Discussions

    Andy Jarman

    3 years ago

    Al I'm in Perth WA. I'm looking for someone to help build a family of giant long neck tortoises. Contact me if you are interested


    4 years ago

    You are amazing! Thank you for such beautiful photos start to finish!


    4 years ago on Introduction

    he or she is beautiful, thanks for sharing. Do you have a link for seeing any of your other work?


    5 years ago on Introduction

    nice job for the kids ............thank you for sharing


    5 years ago on Introduction

    Congratulations on being a finalist in the Concrete and
    casting contest! Best of luck to you! I am in love with this sculpture, just plain lovely.


    That is so adorable !!! I have a leopard gecko and he looks a lot like the one you made ! I want the smaller test piece you made !!!!!!! sigh

    Wow the scale of this project is impressive. And the results are fantastic. I bet this takes the prize for the worlds heaviest gecko.

    You should set up an x-ray machine so people can see your beautiful steel work.


    5 years ago on Introduction

    i had seen your beautiful gecko via the tec eco website-i notice that you don't include clinoptilolite in the mix? i am still trying to understand the chemistry involved and not quite sure what part the clinoptilolite plays but i thought you had used that in the mix? Also what was the proportion of the flyash, please? i have been doing some 'experimental' concrete work-mostly sculptural - magnesium phosphate concrete is an area of interest! Thankyou for sharing your construction method- especially the inner 'sleeve'- i wouldn't have thought of that.. Excellent work, very gecko!

    1 reply

    Reply 5 years ago on Introduction

    nlanga, thanks for your post. I have lost all my notes on the mix ratios, so what I put up was from an imperfect memory of it. Yes the clinoptilolite was an ingredient, but a small percentage. With the additives it was a very "short mix", so the internal foam allowed lots of pressure and vibration to compact the layup.


    5 years ago on Introduction

    Great job, Al. The proportions are perfect. I use a similar technique to make Living Tree Art with internal programmable plumbing systems, different type of concrete. Lots can be done with concrete. Never heard of Hessian. Looking that one up right now! Thnx!


    Great story for gecko to tell his buddies...."I was abducted by a huge alien, picked up examined thoroughly and strange flashes of light (pictures with flash),,,,I was released but when I went back a few days later to figure out what happened ,,,,there was this huge statue of me!!! Then it came to me,,,,they think I am a god!!!!!"