On July 21st every year, we celebrate Belgian National Day and think about all the good things Belgium has to offer: Tintin, cycling, soccer, and– from a more gastronomical perspective– waffles and chocolate. This is an ideal time to reflect upon our chocolate design project from 2013.
A pavilion made out of chocolate must be a cocoa lover’s wildest dream. We teamed up with Prof. Axel Kilian (Princeton University) and the Belgian chocolate manufacturer Barry-Callebaut to discover chocolate’s structural properties and let them inform our methodology for finding the shape of such a pavilion.
The R&D branch at Barry-Callebaut developed a cocoa compound of sugar, cocoa powder, milk permeate, and vegetable oil that would be structurally strong enough to support the pavilion’s own weight at room temperature. We tested the compound mixtures and found that the strength-to-weight ratio of chocolate compounds is quite low — about 24 times lower than standard concrete.
After deliciously physical experiments with chocolate pneumatic shell forms, inverted tree networks, saddle forms and hanging fabric models, we settled for a hanging fabric shell model as a form finding approach for the pavilion. With only the self-weight of the chocolate to carry, this catenary form was the most structurally efficient. As long as creep and global buckling were considered in design, it provided a structural system that could span the farthest using the smallest amount of material. Although it was appealing to exploit the rheological properties of the chocolate and explore flows of forces by pouring material onto formwork or dipping material, the practicality of this application method would break down at a large scale with a limited construction time frame. Considerations such as control over material thickness, adherence to support formwork (whether flow over steep formwork or accumulation on a set of strings), the setting speed of chocolate, and assurance of a monolithic form raised large construction challenges.
We developed a digital parametric model that integrated form finding, shape optimization, planarity mold, and patterning algorithms. The prototype we built consisted of over 70 individual frames of chocolate that puzzled together into an open-air domed pavilion. This real-life chocolate pavilion seemed to come straight out of Willy Wonka’s chocolate factory.
This blog post is based on Alex Jordan *13’s research towards a masters thesis. You can find more about our project here.
Author: Sigrid Adriaenssens
Editors: Jacob Essig, Demi Fang ’17