The freeze-thaw resistance change is important for the grouting material with regard to system operation. Possible frost actions result from the circulation of supercooled (temperatures below 0°C) water-glycol mixtures („brine“) and not due to the frost actions from the surface of the terrain (Note: The geothermal heat pipes have placed the frost-resistant below the natural frost incursion limit at approx. 1-1.5 m below ground level ).
The Freeze-thaw resistance change in building materials, such as Fischer GeoSolid® products, are not damaged by the temperatures occurring in the geothermal probe pipes by freezing excess water or ground water in the pores. This property is important to have a durable and stable backfill material around the geothermal probe in the borehole.