Transparent Self-Cleaning Concrete 3D Printable
When most people think of concrete structures, words like light, airy, brilliant and gleaming seldom pop to the surface. And yet, some architects and researchers are aiming for concrete that could be described by exactly those words.
Architect Will Wittig of the University of Detroit Mercy was the first to attempt to make concrete transparent, or at least translucent. By mixing white silica sand, white Portland cement and fiberglass fibers, he was able to create translucent, domed concrete panels that were about 3 mm thick at the apex and a centimeter at the edges.
The finished panels transmitted about 1 percent of ambient light, enough to give a room a slight glow from bright sunlight. While the experiments succeeded optically, they lacked enough strength to be used in construction. However, I have little doubt that further material research could yield a practical solution. A 3D-printable, translucent, concrete medium opens up many interesting architectural possibilities.
In a similar vein, LiTraCon, of Aachen, Germany, has developed concrete bricks laced with optical fibers. The fibers extend from one end of the brick to the other. Light that falls on one end is transmitted to the other end with very little loss. A brick wall that is sunlit on one side appears to shine with light on the other.
The manufacturing process builds the bricks by alternating thin layers of concrete with layers of optical fibers in a long trough. The finished beam is sliced into bricks, thus exposing the fiber ends. This is a critical part of the manufacturing because the fibers must be exposed to light on each end for effective transmission.
Imagine using 3D printing to lay such a wall in place. This process lays down shorter fibers oriented from outside to inside the wall. Once the concrete is set, a couple of finishing steps smooth the wall surfaces, trimming off excess fibers or exposing slightly buried fiber ends.
Another innovation gives concrete structures a brilliant white finish that never needs cleaning. Scientist Luigi Cassar and colleagues at the Italcementi Group in Bergamo, Italy, mixed titanium dioxide with the cement. In addition to making the finished surface bright white, the pigment actually cleans the air.
Ultraviolet light in sunlight makes the titanium dioxide highly reactive. Pollutants that settle on the surface are broken down into simpler molecules that do not discolor or rinse away with rain. The material has already been used in several large buildings. The self-cleaning surface could remain active for up to 1,000 years. Because it is concrete, it can also be 3D printed.