No longer commercially available, the Z Corporation ZPrinter 650 used inkjet print heads to extrude a binder solution into plaster. Better yet, a second bank of CMYK print heads enabled the printer to make full-colour prints.

I envision a system very much like this one, to print cast stone.

From my perspective, the financial, environmental, and artistic potential of being able to quickly and accurately create concrete architectural furnishings through 3D printing, rather than the current paradigm of formbuilding, mixing, pouring, stripping, and finishing, would be far-reaching and industry-shifting.

Modern architecture has become more about systems. Rather than a monolithic concrete shell, today’s superstructures leverage the best capabilities of any number of materials: steel, glass, ceramics, etc. The interaction of these complex systems are made possible through computer modeling. If the concrete within these systems is already modeled, how much simpler would it be to 3D print the cast stone components, to be installed with exact tolerances into technologically and artistically advanced designs?

I am asked daily to develop casting approaches for cutting-edge geometries. The methods and materials we use to create negative spaces into which concrete and aggregates can be poured are largely the ones that have been used for decades, and in many cases, centuries. At the same time, CAD modeling is allowing architects to contrive designs well beyond the limitations of our capabilities. 3D printing could alleviate the technology gap.

The implications in the field of landscape design are easily as impactful.

ACS has made a name for itself in the field of landscape design with the successful completion of two high profile cast stone installations: the Polk Brothers Park fountain and bench at the entrance to Navy Pier in Chicago in 2016, and the 573’ long serpentine bench/retaining wall in the revitalization of Pier 54 in Manhattan in 2018.

I was responsible for the CAD modeling and form production for both projects.

The Polk Brothers Park fountain consisted of more than 600 unique parts. No two parts were identical. Every single one of the parts was created by modeling and machining a single-use polystyrene foam form. The environmental costs, not to mention energy and time costs of this project were staggering. And yet, the CAD model consisted of 600 watertight geometries that could easily have been 3D printed, straight out of the model, had the technology existed.

Importantly, the Polk Bros Park fountain is an exception. Most projects don’t have the budget to allow for single-use formwork. Architectural designers are currently constrained by the need for repeatability.

As a “cast stone” company, ACS is frequently asked to produce architectural furnishings that look like marble, or granite, or quartz, or, occasionally, pieces that don’t resemble any particular stone, but rather a particular colour or texture. Cement is the common ingredient in our mixes, but we add aggregates and colours as necessary to achieve whatever look is required. We have made furnishings that are orange, pink, black, and green.

The concrete printer I am envisioning uses a system similar to the Z Corp color printers: inkjet color heads could inject colours, using CMYK technology, allowing for literally 100 million color combinations. Colour could be injected into the product only on the surface, or throughout the part, meaning that the “stone” would look authentic even if it were chipped or damaged. Classic stone textures could be achieved, as well as an infinite array of forward-looking designs and colors.

Photographic concrete. Whoever perfects this technology will rule the world. And save the world, too.