A very clear presentation of a highly useful study, thank you! Testing use of unmodified concrete is beneficial, as that is a good baseline starting point, and particularly as it is a much more economical material than 3D print mortars. The issue may be in reliably line-pumping that material without line blockages. Chinese efforts have used "shuttle hoppers" to transport stiff concrete to the nozzle hopper. We use pumping with inline modification near discharge to give zero-slump, and vibration at placement.
A very clear presentation of a highly useful study, thank you! Testing use of unmodified concrete is beneficial, as that is a good baseline starting point, and particularly as it is a much more economical material than 3D print mortars. The issue may be in reliably line-pumping that material without line blockages. Chinese efforts have used "shuttle hoppers" to transport stiff concrete to the nozzle hopper. We use pumping with inline modification near discharge to give zero-slump, and vibration at placement.