Methods and Capabilities
With the lowest possible raw material requirement, I develop and optimize formulations of cement- and gypsum-based mortars.
Typical test methods such as slump, Vicat device and strength measurements on 4x4x16 prisms require sample quantities on a kilogram scale. Instead, I work with a rheometer and heat flow calorimeter, both of which each manage with a few grams of sample and provide very detailed data about sample behavior.
Measuring the workability instead of feeling it
The workability of mortars is crucial for use in construction site practice. Conventional test methods (e.g. slump) or subjective judgments by the craftsman are insufficient to characterize and optimize processing properties. By contrast, rheological measurements provide objective measurement data, for example about the yield point, the viscosity as a function of the shear rate, the thixotropy and the structural strength, from which conclusions can be drawn on a variety of mortar properties. My experience in applied mortar rheology extends into the 1990s back. My first publication was a lecture at an international conference in 1994.
Special mortar rheometers such as the Viskomat NT still need too much material for my purposes, so I work with a research rheometer with serrated plate-plate measuring system. Each measurement thus requires only a few grams of fresh mortar.
Rheometer (Bohlin Gemini 150)
Measuring systems
Heat flow calorimetry rather than strength measurements
A heat flow calorimeter records the timing of the hydration reaction and aids in the selection of the binder as well as in the comparison of additives for their effect on setting or in selecting the best accelerator-retarder combination. The material requirement per measurement is a maximum of three grams of fresh mortar.
Heat flow calorimeter (so-called Erlanger or Kuzel-Calorimeter)
The development of strength in cement-bound mortars is closely linked to the heat of hydration. From the heat flow data strength predictions can be derived and different formulations can be compared very exactly.
Characterization of the setting behavior of gypsum mortars
The stiffening profile of gypsum mortars is very easy to measure and optimize based on the heat flow curves.
Hydration curves of various gypsum mortars
Design of Experiments rather than Trial-and-Error
Statistical tools, such as Design of Experiments (DoE), enable formulators to explore complex, multidimensional spaces against background of experimental variability (noise) with the minimum of resources. By consistently using DoE, I can minimize the amount of experimentation and at the same time accurately estimate it. The expected costs and the demand for raw materials are already known in advance.
The benefits of the DoE methodology:
- Short development times and thus low costs.
- Complex relationships in formulations with black-box additives can be elucidated and mastered.
- Precisely calculable time and thus a corresponding exact cost estimate.
- Traceable and data-based decisions.
DoE shortens development time by minimizing the number of trials required. This further minimizes the already low demand for raw materials. Typically, I need less than 15 kg of your local raw materials (binders, fillers, aggregates, additives).
