CONCRETELY: Fabric-Formed Concrete Columns

Just finished a wonderful workshop with first-year architecture students at the Royal Danish Academy of Fine Arts in Copenhagen. The theme of the workshop was columns.
In the past four years I have organized and taught a number of similar full-scale workshops but never written much about the workshop frame. This post will go through some of the thoughts behind the elements and activities of the workshop.

[The family of fabric-formed concrete columns]

[The formwork structures on pour day with the concrete pump in the background]

Studying concrete in relation to its mold
Concrete is studied best in relation to its formwork, as material and process. The use of fabric formwork is an excellent tool to introduce concrete and formwork principles in order to enforce an individual and curious understanding of what concrete and the process of casting is all about.

The concrete workshop is a highlight of the TEK1 course, a mandatory four-week course about architectural technology. This year, 35 students (a quarter of the class) were in my workshop.

Columns

The theme of the workshop was columns. As the most basic structural and architectural element the column is loadbearing as well as the defining space. The student's approach varied greatly. And their focus sprung from either the textile principles of draping or sewing, or principles of the construction process and how to use minimal means and simple process to construct their formwork.

For a fabric-formed column the main objectives of the formwork is a) contain concrete, b) stay in place (erect), c) additional sculptural features. A and B remain the crucial aspects but the point is, of course, that by erecting the formwork structures in a clever way, the formwork-tectonic principles also have a direct formal consequence on the concrete column. Furthermore, the closing detail or seam of the fabric is important as well. Basically, focus remains on a few important details and their effect - as ornament or as 'invisible'

Afternoon 1: Brainstorm

First step in our workshop is a one-hour brainstorm. At this workshop, 6 groups sketched and played with fabric for an hour after which we have a short pin-up. The point is that by sharing these initial ideas creates a pool of knowledge as well as a number of themes and categories to discuss. Themes of concrete's sculptural form, textile notions, and design principles derived from construction become clear from discussing the sketches and ideas. Looking back now it seems that this initial categorization of approaches has helped the teams to remain clear - at least the themes are pretty clear in their work, anyway.

Afternoon 2: Plaster

The workshop is all much about making. And about making something fast.

A great way to make decisions and learn from principles in fabric formwork, is to do small scale casts in plaster. This is a method practiced at CAST and it works really well in the student workshops. For this workshop we had a plaster lab allowing us to mess around with plaster and the student teams were super enthusiastic, playful and productive.

[Detail of plaster cast in a fabric mold with impactos]

[learning by doing, casting plaster in fabric molds. The blow-out experiences are much nicer to experience first at a smaller scale]

[Selection of plaster models cast in a few hours]

Day 4: First Concrete mix and pour

As a way to change scale and focus from plaster to concrete, it was fun and appropriate to build simple formwork frames as well as mixing and placing concrete, heavy as it is. Each team had their plinth and were given U profile reinforcement to place according to their column design.

It turned out excellent to leave the formwork boards on the foundation during the entire workshop. In this way the column formworks could be fastened to the ground.

[Students placing concrete mixed in the mixer in the background. The wooden formwork boards allowed the teams to attach their formwork bracing]

Constructing full-scale formwork structures

Producing several plaster casts allows teams to discuss construction techniques as well as the expression and geometry of their finished column. The full-scale work entails a different and much more material oriented approach. One team wanted to stitch their formwork together and had to devise a special needle tool to do it at this large scale, with a thick nylon rope, and in a controlled manner.