The scion of a family of masons going back several generations, Carlos Martín Jiménez is an expert in the ancient technique of tile-vault construction. He talks about building the first two Droneport prototypes.

L’Architecture d’Aujourd’hui: Can you describe the tile-vault method of construction?

Carlos Martín Jiménez: You need a certain amount of prior knowledge both with respect to the materials and their properties and with respect to geometry. First, you trace the arc of the vault above the space to be covered. Then, you begin to build the springing points, using tile bricks smeared with wet plaster: since the plaster dries fast, the bricks stay in place along the line of the curve you’re following. You need a certain amount of skill and dexterity to follow the curve in space with hardly any formwork. First you build the four ribs, followed by the webbing, in two layers: for the first you use plaster on two edges of the brick, for the second you use plaster on the brick’s face. The two layers need to be correctly laid, either in classic rows or in chevrons.

AA: What were the constraints and challenges when building the first Droneport prototype in Madrid using DuraBrics?

CMJ: It was very stimulating to work with the architects, the MIT team and the professors and students at the architecture faculty of the Universidad Politécnica in Madrid. The Droneport’s geometry, which differs from that of a traditional vault, was a challenge in itself. But we had a good guide to follow. The use of compressed-earth bricks was also new; their properties are different from those of fired bricks, for example the moisture- absorption coefficient, which made it difficult to get the bricks to hold together. The problem was solved through a combination of DuraBrics and ceramic bricks. In Madrid there was a laboratory that helped us work out certain aspects of the prototype. By testing the built prototype, and after looking at videos of its construction, we changed the webbing courses from straight to circular, since that responded better to the actual loading distribution.

“It was very stimulating to work with the architects.”

AA: And what about the Venice prototype?

CMJ: The change in scale and the possibility that the vault might be permanent led us to reconsider the adhesive between the DuraBrics. It was difficult to get them to hold in place with plaster, so we had to invent new mortars on site that ensured the cohesion of the vault and its durability. For the same reason, the first layer of the vault was built with traditional fired tiles, and the second two with DuraBrics.

AA: Do you think the ambitions of the Droneport project can be met?

CMJ: Yes, the project is very interesting, and I believe it is possible to make it work. It needs a few adjustments in light of the lessons learnt in Madrid and Venice. They’ll also have to make sure that the workers who build the Droneport in Rwanda have been properly trained in the construction of tile vaults.