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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 |