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Ground source heat pump cement-based grout literature review. Final report

Technical Report ·
OSTI ID:354806
Ground source heat pumps (GSHPs), also known as geothermal heat pumps (GHPs), are an attractive high efficiency heating and cooling technology. The ground heat exchangers (GHXs) used with this type of equipment must be adequately sealed to protect the subsurface environment, while also providing good heat transfer. Especially with vertical-bore ground heat exchange systems, the heat exchanger wellbore must be grouted with a material that seals aquifers from contamination, while avoiding voids and maximizing heat transfer capabilities. Numerous types of grout materials are available for sealing the boreholes, the most common being bentonite-based and cement-based grouts. This report summarizes results of an extensive literature review of cement-based grout materials, applications, application techniques, and limitations. This literature review was performed as part of work aimed at developing new, better performing cement grout materials, grouting techniques, and information, especially as related to grout sealing and heat transfer properties. The work also helps better define when one type of grout should be used vs. another. Similar studies have been performed under related research contracts to study bentonite-based grouting materials, and similar reports are available for those grouting materials as well. See the reference section at the end of this report. A significant number of different grouting applications, standards and practices exist. This study has sought to summarize the various standards and practices that exist for the more common types of applications, so that a more logical set of practices, standards, and limitations may be developed specifically for geothermal heat exchanger sealing applications. 112 refs.
Research Organization:
Electric Power Research Inst., Palo Alto, CA (United States); South Dakota State Univ., Brookings, SD (United States)
Sponsoring Organization:
Electric Power Research Inst., Palo Alto, CA (United States)
OSTI ID:
354806
Report Number(s):
EPRI-TR--109166
Country of Publication:
United States
Language:
English