Nanocomposites and nanomaterials
The effects of nano- and micro-particle additives on the of 3D printable cementitious materials – A review
Sikora P.1,2
1 Technische Universität Berlin, Department of Civil Engineering, Gustav-Meyer-Allee 25, 13355 Berlin, Germany
E-mail: pawel.sikora@zut.edu.pl
2 Faculty of Civil Engineering and Architecture, West Pomeranian University of Technology, Szczecin, Al. Piastow 50, Szczecin 70-311, Poland

Additive manufacturing (AM), also referred to as 3D printing, is a method of constructing a structure via a layer-by-layer process. It is one of the most successful emerging fields in civil engineering. This interest owes to new structural possibilities, which cannot be achieved with a conventional construction process. The concrete for AM technology differs noticeably from castable concrete; it should be characterized by good pumpability, extrudability, buildability as well as fast setting. These can be achieved by considerable mixture design modifications, mainly including significant reduction of the water-binder (w/b) ratio, increasing the amount of fillers in the mixture, as well as by introducing various water-reducing and viscosity-modifying additives. Unfortunately, increasing the amount of cement in the composite causes a significant increase in the cost of material production. Therefore, solutions are sought to replace cement with various types of nano- and micro-size admixtures. The introduction of cement admixtures and additives significantly changes the fresh and hardened properties of the cementitious composite. Therefore, it is important to choose the right material and its quantity to reduce production costs while maintaining the same properties of the composite. This works presents a critical review of the effect of nano- and micro-size admixtures on various rheological, strength and durability properties of the 3D printable cementitious materials.

Acknowledgments: This project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 841592. Supported by the Foundation for Polish Science (FNP)