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Pipe Table 1: Thermal Conductivities of Typical Grouts and Backfills (1-4)
 
k (J/m*K)
Grouts without Additives
20% Bentonite
0.73
30% Bentonite
0.74
Cement Mortar
0.69-0.78
Concrete @ 2100/2400 
1.04/1.38
Concrete (50% Quartz Sand)
1.9-2.9
Thermally Enhanced Grouts
20% Bentonite--40% Quartzite
1.5
30% Bentonite--30% Quartzite
1.2-1.3
30% Bentonite--30% Iron Ore
0.79
60% Quartzite--Flowable Fill
(Cement + Fly Ash + Sand)
1.85

1. CRC Handbook of Tables for Applied Engineering Science, Chemical Rubber Co., Cleveland, 1970.
2. C. P. Remund, "The Effect of Grout Thermal Conductivity on Vertical Geothermal Heat Exchanger Design and Performance," South Dakota State University, 1996.
3. "Thermal and Water Vapor Transmission Data," 1993 ASHRAE Handbook-Fundamentals, p.22.8. Atlanta: American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc., 1993.
4. M. L. Allan, "Improvement of Cementitious Grout Thermal Conductivity for GHP Applications," Preliminary Report, Brookhaven National Laboratory.

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