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Table 2 Properties of the soil, grouting and pipe material used in the experiment

From: Impact of operational temperature changes and freeze–thaw cycles on the hydraulic conductivity of borehole heat exchangers

Soil
 Dry density DIN EN 13286-1 (2003) ρd 1.71 g cm−3
 Grain density DIN EN ISO 17892-3 (2015b) ρs 2.67 g cm−3
 Porosity DIN EN ISO 17892-2 (2015a) Ф ~ 36 %
 Hydraulic conductivity DIN EN ISO 17892-11 (2019) K 1 × 10–8 m s−1
 Thermal conductivity (Sat.) Drefke et al. (2017) λ 2.3 W m−1 K−1
 Liquid limit DIN EN ISO 17892-12 (2020) WL 23.5 %
 Plastic limit DIN EN ISO 17892-12 (2020) WP 21.3 %
 Plasticity DIN EN ISO 17892-12 (2020) IP 2.2 %
Grout
 Suspension density VDI 4640-2 (2019) ρs 1.47 g cm−3
 Marsh funnel time (4.76 mm) DIN EN ISO 10414-1 (2009) tf 51 s
 Water bleeding (24 h) VDI 4640-2 (2019)   3 %
 Uniaxial comp. strength (56 d) DIN 18141-1 (2014) Cu 5.47 N mm−2
 Hydraulic conductivity DIN EN ISO 17892-11 (2019) K < 1 × 10–11 m s−1
 Hydraulic system conductivity (FTC0) VDI 4640-2 (2019) K 7.0 × 10–10 m s−1
 Hydraulic system conductivity (FTC6) VDI 4640-2 (2019) K 2.8 × 10–9 m s−1
 Thermal conductivity Manufacturer data λ > 2 W m−1 k−1
Pipe
 Pipe material Manufacturer data Polyethylene PE 100-RC
 Outer/inner diameter Manufacturer data do/di 32/26 mm
 Wall thickness Manufacturer data s 3.0 mm
 Surface roughness Manufacturer data Rt 1.86 µm
 Thermal conductivity Manufacturer data λ 0.40 W m−1 K−1
 Coefficient of thermal expansion Manufacturer data α 180 × 10–6 K−1