What’s on the minds of our young employees?

My name is Rafael Casquero Díaz. I am a 26-year- old Spanish chemical engineer from Madrid, and since June I have been doing a product management internship for sprayed concrete admixtures at Sika Services AG in Zurich.

I want to write about 3D printing processes, as from my point of view it is one of the most interesting topics I have covered during the internship. And what is more, it marks one of today’s most revolutionary construction concepts. Given Sika’s well-established position in the construction chemical products market, this modern construction technology is very interesting in terms of the potential business development.

3D printing for construction

At the end of the last decade in 2009, 3D printing took off as an exciting way to construct special architectural geometries or to produce efficient residential buildings. Since then, the US, the Netherlands and China have led research and development activities focused on this new technology. The increasing rate of growth of the global population and with it the need to build affordable housing faster and more sustainably gave rise to the idea of using a suitable and effective technology such as 3D printing to build houses.

Wireless-controlled robotic arm to shoot concrete

3D printing was already being used to create medium-sized sculptures of small everyday objects. The technology consists of a computer-automated creation process, in which the original shape and size are designed by a software program, and a printing device then generates the required object in 3D. A number of universities around the world are investigating industrial-scale procedures to create layers of extruded concrete using a large building machine in order to build houses.

The first troubleshooting tests

This year the architecture faculty of University Graz started a very interesting project focused on combining a wireless-controlled robotic arm with the low-output MiniShot concrete extrusion system invented by Sika. Originally, the MiniShot system was designed for testing admixtures for sprayed concrete using ultrasonic pulsating cells with the aim of saving time and reducing costs compared to high-scale testing procedures. However, TU Graz was interested in the MiniShot pumping system as a continuous extrusion building device without pulsation, avoiding the use of a compressed air unit.

Like a mortar mix

Sika assisted University Graz with installing the MiniShot pumping system, performing the first laboratory trials, carrying out a troubleshooting test to detect the most common pumping-related issues, and adding a special nozzle for the Sigunit® accelerator (chemical product for decreasing the setting time of the mortar to develop higher early-compressive strength), (see figure 1).

The mix design was a critical part of the technical support, conforming the extruded material pumped through a small hose. The mix design consisted of cement, (Sika® ViscoCrete®) superplasticizer, thixotropic filler (SikaThixo-14) and 0-1 mm of sand and water. It could be described as a mortar mixture due to the small size of the aggregates.

First laboratory trials

An architecture student was given a project assignment to create highly precise 3D printing sculptures and geometric figures by applying extruded concrete in a laboratory. The first laboratory trials were affected by a control safety issue, which meant that Sika engineers had to work from 10 am to 10 pm to complete the technical support procedures.

Combination of robotic system, software program and MiniShot pumping system

In my opinion, the combination of robotic system, software program and MiniShot pumping system was a brilliant idea if we consider the highly precise work developed by the extrusion nozzle when creating the Sika logo shown in figure 2. The project met the requirements of 3D construction printing as the build-up of the figures was formed with several fast setting layers of cementitious material.

The partnership of trust between Sika and University TU Graz was based not only on developing business but also on enjoying several activities to mark the end of the architecture degree course. For instance, the architecture professors invited us to take part in a final presentation of one of the subjects in which different groups of students provided specific insight into the same project.