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Table 1 Thermal properties of selected soil (ASHRAE, 2000)

From: Earth-air heat exchanger as a green retrofit for Chandīgarh—a critical review

  Dry density, kg/m3 Conductivity, W/(m K) Diffusivity, m2/day
Soils    
 Heavy clay (15 % water) 1925 1.4–1.9 0.042–0.061
 Heavy clay (5 % water) 1925 1.0–1.4 0.047–0.061
 Light clay (15 % water) 1285 0.7–1.0 0.055–0.047
 Light clay (5 % water) 1285 0.5–0.9 0.056–0.056
 Heavy sand (15 % water) 1925 2.8–3.8 0.084–0.11
 Heavy sand (5 % water) 1925 2.1–2.3 0.093–0.14
 Light sand (15 % water) 1285 1.0–2.1 0.047–0.093
 Light sand (5 % water) 1285 0.9–1.9 0.055–0.12
Rocks    
 Granite 2650 2.3–3.7 0.084–0.13
 Limestone 2400–2800 2.4–3.8 0.084–0.13
 Sandstone 2570–2730 2.1–3.5 0.65–0.11
 Wet shale   1.4–2.4 0.065–0.084
 Dry shale   1.0–2.1 0.055–0.074
Grouts/backfills    
 Bentonite (20 % solids)   0.73–0.75  
 Cement   0.70–0.78  
 20 % bentonite −40 % SiO2 sand   1.48  
 Concrete (50 % SiO2 sand)   2.1–2.8