Thermo-mechanical properties of grout materials have been investigated, which are used for backfilling a ground heat exchanger in the geothermal heat pump (GHP) system. The thermal conductivity and viscosity of nine different bentonite grouts and a cementitious grout with various mix proportions have been considered in this study. The bentonite grouts indicate that the thermal conductivity and viscosity increase with the content of bentonite or filler (silica sand). In addition, material segregation can be observed when the viscosity of grout is relatively low. The saturated cement grouts appear to possess much higher thermal conductivity than the saturated bentonite grouts, and the reduction of thermal conductivity by drying the cementitious grout is less than the case of the bentonite grouts. Maintaining the moisture content of grouts is a crucial factor in enhancing the efficiency of ground heat exchangers.
Choi, H., Lee, C., Gil, H. and Choi, H. (2008). 'Experimental Study on Thermo-mechanical properties of Backfilling Grout for Close-loop Vertical Ground Heat Exchanger'. SET Proceedings, 7(1), pp. 1103-1110. https://doi.org/10.65582/set.2008.148
