Our Setup

De Huizenprinters - Full setup

Below is a schematic of our 3D concrete printing system. On the left side you can see the robot to which the print head is attached. On the right side the mortar and additive pump are schematically shown.

Stage 1: Mortar Mortar is automatically produced by the Duomix 2000 which we tuned ourselves. This pump first feeds dry mortar into the horizontal mixing chamber. In the picture shown as “Water”. Here the water is also added in fine doses. After this the mortar is collected in the vertical mixing chamber where it is mixed one last time before it is pumped.

The 'standard' setup of the Duomix was unfortunately not constant enough for our process. We found that fluctuations in the water supply caused the vertical mixing chamber (as described above) to clog up. For this reason we used a flow sensor to control the water supply more closely. You can find the code for this at; xxx.

For more information about the Duomix 2000, go to: https://www.schoonewiltechnieknijverdal.nl/Producten/duomix-2000/

Stage 2: Accelerate The 'freshly' prepared mortar arrives at the print head on the robot. First the thixotropy of the material is broken down by mixing it with a lot of energy. This mixer is just a simple shaft with pins on the side. Then the accelerator is added via a 'needle injection' in the middle of the mixing chamber. It is very important to ensure that the flow of the accelerator is constant. This needle is very prone to clogging!

After the accelerator has been mixed for about 20-30 seconds, it is extruded at the bottom of the print head. Here the object is built up layer by layer.

Additive The additive station is used to add the accelerator to the mixing chamber under a constant flow via a ‘needle injection’. It is important to keep this accelerator moving during the print to prevent settling.

For more information on the accelerator pump go to: https://emecwebshop.com/en/product/emec-prisma-dosing-pump/

When preparing mixes for concrete printing dust become an issue. We use a welding fume dust extractor when working with powder mix.

While printing the mix is wet and does not produce dust. But when dried, the movement of objects and cleaning can create dust again. What is important is to vacuum the area regularly. Do not use a broom as it kicks the dust up again. You can also use a 'scrubber' which is even better as it uses water to scrub the floors.