Combination of concrete and 3D printing

As part of the Dfab-House, researchers at ETH Zurich manufactured a lightweight concrete concrete slab of 80 square meters. This is the first full-size architectural project using 3D sanding for its formwork.

The "Smart Slab" project combines the structural strengths of concrete with the design possibilities of 3D printing. The construction method was developed by the group led by Benjamin Dillenburger, assistant professor of digital construction technologies at ETH Zurich. The smart ceiling is also one of the basic elements of Dfab House – a house designed, planned and built on the nest with digital processes. Recently, the concrete ceiling was installed in the nest of Empa and Eawag in Dübendorf. The ceiling of 80 square meters consists of a total of eleven concrete segments and weighs 15 tons.

In the "Smart Slab" project, researchers do not manufacture the components themselves with 3D printing, but only their formwork. According to the ETH, work is being done on a large format 3D sand printer. The formwork elements are thus a kind of artificial sandstone. This method offers advantages over the actual printing process in that the reinforced concrete can be used more efficiently and the structure can be extracted to the nearest millimeter.

Software developed for manufacturing

It is able to record and determine all relevant parameters for production. The geometry of the ceiling could thus be designed so that at each point exactly as much concrete as structurally necessary. The end result is a filigree structure composed of main ribs and smaller, thinner ribs. The first bear the burden of construction, and thinner ribs, according to the ETH, serve architectural expression and room acoustics.

The "Smart Slab" project involved different industrial partners. The 3D-Sandformschalungen and the wooden formwork were produced by two separate companies and finally materialized by a third company. For this purpose, the fiber reinforced concrete was first injected into the sand molds and the remaining concrete was then poured into the wooden envelope.

The hardening of the concrete segments lasted two weeks, according to the EPF. Then they were ready to be transported to the Dübendorf nest. Once there, a crane hoisted the elements onto the Mesh Mold Wall, with an underlying double curvature, already manufactured in advance by the "In situ Fabricator" construction robot (reported by Baublatt). The bias was then made on the spot. The craftsmen were pulling the steel cables through the concrete beams longitudinally and transversely. According to ETH, the load on the system can be massively increased by the tension of the cables.

In a next step, the prefabricated wooden modules using the new wooden construction method "Spatial Timber Assemblies" (Baublatt) are delivered to the construction site and assembled. This should later be a two-story wooden construction. (bp / mgt)