EWS-tech II

Development of verifiable quality criteria for borehole heat exchanger groutings under realistic boundary conditions


  • Geothermal


  • Research
  • Development
  • Knowledge transfer


  • Public funds


04/2016 – 12/2019 (3.75 years)


2.1 m. EUR


Within the joint research project EWS-tech II examinations on the grouting quality of borehole heat exchangers (BHE) are carried out. These examinations result in a recommendation catalog for grouting materials that can e.g. be used by legislators or grouting material manufacturers.


Ministry of the Environment, Climate Protection and the Energy Sector of Baden-Württemberg


  • Steinbeis Research Institute Solites
  • Karlsruhe Institute of Technology (KIT) – Institute of Applied Geosciences (AGW)
  • Karlsruhe Institute of Technology (KIT) – Materials Testing and Research Institute (MPA Karlsruhe)
  • EIFER (European Institute for Energy Research)


  • Assessment of the behavior of BHE grouting materials in boreholes with groundwater flow. The focus of these examinations lies on boreholes that connect aquifers with different pressure potentials.
  • Evaluation of the influence of the roughness of the borehole wall on the system permeability, taking into account the interaction between different grouting materials, wall topographies and groundwater flows.
  • Advantages and disadvantages as well as limits of application of magnetite doped grouting materials and evaluation of the associated geophysical measuring methods
  • Long term integrity of grouted BHE


In order to achieve the objectives, various complementary test setups are used by the project partners. In the planned experiments, four magnetically doped grouting materials with different rheological properties, that are newly developed by the project partner MPA Karlsruhe (KIT), will be used to investigate the relationship between the rheological properties and the grouting quality.

One of Solites’ key work packages is the visualization of the grouting and hardening process of six meter high geothermal borehole heat exchangers in the presence of different groundwater flows. A transparent borehole is used for these experiments. In addition, real-scale experiments are performed to proof the validity of the six meter tests for real-scale conditions.

The experimental procedures also include the use of automatic grouting control based on magnetic susceptibility measurements.


The main result of the research project is a recommendation catalog for borehole heat exchanger grouting materials. This catalog includes:

  • Requirement criteria for BHE grouting materials (also with regard to the magnetic doping)
  • Recommendations on the grouting technique in the case of boreholes that penetrate one or more groundwater layers
  • Assessment of the detection limits and validity of automatic grouting control methods

This project has received funding from

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