Start of funding 01.01.2021

Ultrafast “fluid-to-solid” transitions in concentrated suspensions

Prof. Dr. Torben Gädt
Technische Universität München
Lehrstuhl für Bauchemie - Fakultät Chemie

Prof. Dr. Gaurav N. Sant
University of California, Los Angeles (UCLA)
Samueli School of Engineering



Slurry-based additive manufacturing is of broad interest in applications ranging from gel casting of ceramics, to the production of structural construction components. In each case, a central issue that complicates manufacturing is the slow temporal evolution of properties (e.g. stiffness) in slurry-based “printing inks” after deposition. This slow fluid-to-solid transition greatly limits achievable architectures. To truly exploit the opportunities unlocked by generative design, topology optimization and free-form printing (i.e., producing overhanging shapes without an underlying support), it is necessary to develop approaches for “ultrafast solidification”. New ultrafast and switchable curing is therefore necessary to print architected structural components, e.g., stretch dominated structures, which achieve unparalleded strength-to-weight ratios.

This collaboration will leverage ongoing activities at TUM and UCLA focused on the development and formulation of: (a) ultrafast curing materials, and (b) 3D-printing platforms and processes. The team will work on developing a hybrid inorganic-organic curing mechanism with ultrafast setting properties and also will adapt the printing process to the new binder system in order to demonstrate the feasibility of the new concept.

Final report:
Within the framework of the funded project, a novel hybrid inorganic-organic binder system for additive manufacturing with aqueous suspensions was developed. This system undergoes an ultrafast fluid-to-solid transition once a specific initiation temperature is reached. During the development process, the team at TU Munich under Prof. Gädt focused on the chemical composition of the organic binder. The interim target of developing an organic binder that functions in a strongly basic environment and has an initiation temperature of about 60°C was achieved in this phase. The knowledge gained from these studies was then used in close collaboration by the group of Prof. Sant at UCLA. There, the rheologic properties of the mixture containing organic binder and aqueous suspensions were adjusted for 3D printing. The novel printing paste obtained by this process now enables printing complex structures (e.g., overhanging shapes, non-planar) that are not printable with conventional suspension-based systems. BaCaTeC funds were used to facilitate a three-week visit to Los Angeles by a student from Munich to gain practical experience. This allowed the exchange of working methods and direct conversation between the people involved. The good collaborative work led to several publications and conference contributions [1–4].

Future research will continue to apply the organic binder to various aqueous suspensions and develop a temperature-independent initiation method for the organic binder that is also suitable for highly loaded suspensions.

[1] S. B. Kandy, I. Mehdipour, N. Neithalath, A. Kumar, M. Bauchy, E. Garboczi, S. Srivastava, T. Gaedt, G. Sant, Materials &. Design 2022, 221, 110905.
[2] S. Remke, G. Sant, T. Gädt, ce/papers - Proceedings in Civil Engineering 2023, 6, 818–824.
[3] S. Remke, S. B. Kandy, O. Rindle, G. Sant, T. Gaedt, https://doi.org/10.1016/j.matdes.2025.113598.
[4] S. B. Kandy, S. Remke; T. Ranganathan, S. Kiran Wani, X. Dai, N. Neithalath, A. Kumar, M. Bauchy, E. Garboczi, T. Gädt, S. Srivastava, G. Sant, https://doi.org/10.1016/j.cemconcomp.2024.105905.