July 29

Kelvin 6k released a time lapse video of a print outdoors in India using a very unique printer quite unlike the others we have seen on this channel but perhaps most similar to UTU in Ukraine. It is a single pillar with an extending boom from which the concrete extruder. The video only has 20 views! I don’t think they used a large aggregate concrete, that stuff is below.

Wondering about concrete mixes? Wilson Ricardo Leal da Silva shared this link on linkedin recently describing some mixes for large aggregate which is hopefully a good way to increase strength and decrease cost of 3d printed concrete mixes.

Large aggregate is really hard to push through a small diameter hose. There is a natural separation of materials that splits a homogenous mix into different parts. Anyone who knows about concrete knows this is bad. Large aggregate tends to go towards the center of the hose. Dr Khoshnevis published a paper in 2017 describing how this factor makes large aggregate concrete weaker than small aggregate printed concrete. The only way to mitigate this separation effect in the hose is to make the material homogenous again by mixing it thoroughly after the hose before the final extrusion.