While industries such as medicine, aerospace, and automotive often seem to steal the wow factor within the 3D printing spotlight, the construction zone has certainly not disappointed in terms of spectacular headlines. And as a wide range of materials continue to prove themselves, cement has certainly been no slouch; in fact, you could spend many hours poring over the different types of research involving both cement and additive manufacturing—from experimentation with self-reinforced strain hardening composites, spray-based materials, and even self-healing systems.

Now, researchers are studying how varied calcined clay affects cement for 3D printing, with their findings released in “Effect of different grade levels of calcined clays on fresh and hardened properties of ternary-blended cementitious materials for 3D printing.” Pointing out that concrete is often used in both particle bed- and extrusion-based 3D concrete printing (3DCP), the authors consider extrusion to be more suitable for the large scale.

While printability, buildability, and extrudability are key, other factors are necessary for quality extrusion, such as high fluidibility, low viscosity, and suitable layer adhesion. Most studies regarding cement include additives like ash, limestone, silica, and slag—offering improved sustainability with decreased use of Portland cement; however, with pressure on the additives now too, they are becoming more depleted.

Calcined clay is clay that has been converted into a ceramic via firing in a kiln up to 1500 degrees Fahrenheit. The material is most often used as a soil amendment on baseball fields. Previous research has pointed to calcined clay as a good alternative due to:

• Low CO₂footprint
• Abundant raw materials
• Good compressive strength
• Capillary porosity refinement with pozzolanic reactions

Calcined clay may be prone to unpredictability though, due to manufacturer variances in production, as well as deviances caused by temperature, differences due to the structure and purity of raw materials, and more—along with reactivity dependent on metakaolin (MK).

Keep reading on 3Dprint.com