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Title: Thermally conductive cementitious grout for geothermal heat pump systems

A thermally conductive cement-sand grout for use with a geothermal heat pump system. The cement sand grout contains cement, silica sand, a superplasticizer, water and optionally bentonite. The present invention also includes a method of filling boreholes used for geothermal heat pump systems with the thermally conductive cement-sand grout. The cement-sand grout has improved thermal conductivity over neat cement and bentonite grouts, which allows shallower bore holes to be used to provide an equivalent heat transfer capacity. In addition, the cement-sand grouts of the present invention also provide improved bond strengths and decreased permeabilities. The cement-sand grouts can also contain blast furnace slag, fly ash, a thermoplastic air entraining agent, latex, a shrinkage reducing admixture, calcium oxide and combinations thereof.
  1. (Old Field, NY)
Publication Date:
OSTI Identifier:
Report Number(s):
US 6251179
DOE Contract Number:
Resource Type:
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY
Country of Publication:
United States
thermally; conductive; cementitious; grout; geothermal; heat; pump; systems; cement-sand; cement; sand; contains; silica; superplasticizer; water; optionally; bentonite; method; filling; boreholes; improved; thermal; conductivity; neat; grouts; allows; shallower; bore; holes; provide; equivalent; transfer; capacity; addition; bond; strengths; decreased; permeabilities; contain; blast; furnace; slag; fly; ash; thermoplastic; air; entraining; agent; latex; shrinkage; reducing; admixture; calcium; oxide; combinations; pump systems; bore holes; cementitious grout; provide improved; improved thermal; calcium oxide; thermal conductivity; fly ash; heat pump; heat transfer; thermally conductive; silica sand; geothermal heat; thermal heat; sand grout; provide improve; blast furnace; bond strength; /106/166/507/