3D Printing Concrete Directly From Mixer Truck

Is on site batch plant mixing obsolete?

I recently spent 3 weeks in Calgary Canada commuting daily into the indigenous territory of the Siksika nation where Nidus 3D was printing the 3rd and 4th quadplexes from their 16 unit pilot project in the region.

On the first visit in 2023 Nidus was using the batch plant mixer on their Cobod system and for many reasons including the extreme climate the batch plant mixer had substantial challenges. On separate occasions during my first visit, the generator and pump both had issues which ended the day of printing.

This time around Nidus has implemented a new solution I had never before seen in person which has the potential to dramatically increase availability of printable material and reduce labor on site. Instead of hydrating the dry mix on site Nidus worked with Lafarge to batch mix the custom concrete at the Lafarge concrete plant an hour away and have it delivered in a regular mixing truck. From the truck, material is deposited into a pump which has sufficient precision to feed the printer. Long term one could imagine a truck which has a more precise pump as a built in feature.

The primary issue with this strategy is the length of time the truck is required on site. Typically these trucks dump their load as quickly as possible so they can move on to the next job site and make more money. Often they charge an hourly rate so keeping the truck on site through an entire print day may be very costly.

The key benefit to this strategy is reducing on site labor. By outsourcing material mixing and hydration, larger concrete companies which benefit from economies of scale handle one of the dirtiest parts of the job. When cementitious material arrives hydrated it dramatically reduces the airborne silica dust on site making for safer working conditions.

One way to preserve the benefits of off site mixing while navigating hourly concrete truck charges could be some material silo which can hold the wet mix in a printable state through agitation or chemical means so that the truck can go back to fill up instead of waiting on site.

Kudos to Nidus 3D for continuing to push boundaries driving construction automation forward through the challenging process of innovation. The future of technology will not come from people copying the status quo, it will arrive from the hands of those willing to try new things which have never been achieved before.

Being in the region so long I got to see many processes not previously featured on this platform including expanding spray foam insulation, pouring a bond beam, placing window and door lintels to facilitate printed concrete overhangs and more. We even got a glimpse of utilities for the gantry system besides just the printing itself.