Removing Formwork

Taking off the formwork...



Voila! The top is very smooth and nice even consistency.

The Pour

Finally, the day of the pour.

The dye was a powder-based blue dye. We mixed the dye and the concrete dry first, to make sure it was evenly mixed. Then add water.....

Blue dye got everywhere!!! Sorry, Nick and Kirstie ;)

We mixed about 160# of concrete with the dye. Poured it, and were way short. We mixed more, and more and more, until the form was filled...... 300 lbs (136kg) TOTAL!!!

Formwork 1

Creating and ellipse is harder than previously imagined. To make the form I bought a 1/2" sheet of melamine faced OSB. The overall table dimensions were about 4' x 3'. Next we wanted to draw an ellipse on the board. With all the computer software out there, you would think this would be easy. No sir, back to the times of Brunolleschi, when all you had was a piece of string, some charcoal, and a couple of sticks.
We used this website to find the foci of an ellipse.

Next, we pounded a couple nails into the board, and cut our string; then, attached the charcoal to draw the ellipse.

We wanted to somehow anchor the side walls (masonite) into the base of the form: in comes the router. With a 1/4" bit, we fixed the string to the router handle and routed out the shape.

Then added a few T-shaped supports around the ellipse to prevent any collapsing sides, and VOILA, the formwork is ready!

The design

A little project came about to design and fabricate a low table. I thought it would be nice to experiment with an atypical material: concrete.

Here is a screen shot of the Revit model to explore the form.

Some preliminary sketches: