Concepts for precise temporal control of the visco-elastic properties of concrete -- new multi-component admixtures and their structure-activity relationships

• Applicants: Professor Dr. Torben Gädt; Professor Dr.-Ing. Dirk Lowke
• Subject Area: Construction Material Sciences, Chemistry, Building Physics
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 540247966

In the context of current socio-economical developments, ever more challenging construction tasks, or new disruptive manufacturing technologies, concrete technology faces new demands regarding fresh concrete properties. Long processing times, pumping to great heights, use in concrete 3D printing, or the increasing use of supplementary cementitious materials or admixtures, together with the urgent need to reduce the ecological footprint, require new concrete technology concepts. Here, the spatial and temporal control of the visco-elastic properties of (fresh) concretes with a new generation of admixtures is important. The aim of the proposed project is, therefore, fundamental research into a new formulation concept to enable temporally precise control of the processing and hardening properties of cement-based suspensions. This formulation concept will be based on the interaction of two to three additives of different active ingredient classes. Specifically, additives with two to three active ingredients with different mechanisms of action are examined, with the objective a) to disperse, b) to retard, and c) to accelerate. The active ingredient components should interact synergistically in such a way that a high plasticizing effect over a long period (phase I - processing) with simultaneously high green strength (phase II - solidification) and/or high early strength (phase III - hardening) can be realized. The transition between phase I and phase II or III should be within a short, controllable period and occur within a few minutes to ensure safe, practical application. To achieve this objective, the research project applied here will focus on both colloid-chemical effects at the solid-fluid interface and the control of the early hydration reaction.

• DFG Programme: Research Grants