Table 2 Filter paper equations of different authors

ASTM D5298

Total and matric

w < 45.3

5.327 − 0.0779w

ASTM D5298

Total and matric

w > 45.3

2.412 − 0.0135w

Chandler et al. (1992)

Matric

w < 47

4.842 − 0.0622w

Chandler et al. (1992)

Matric

w > 47

6.050 − 2.48 Log w

Oliveira and Marinho (2006)

Matric and total

w < 33

4.83 − 0.0839w

Oliveira and Marinho (2006)

Matric and total

w > 33

2.57 − 0.0154w

Leong et al. (2002)

Matric

w < 47

4.945 − 0.0673w

w > 47

2.909 − 0.0229w

Leong et al. (2002)

Total

w < 26

5.31 − 0.0879w

w > 26

8.778 − 0.222w

Haghighi (2011)

Total and matric

ψ < 500 kPa

33.97w^−0.33 − 4.55T^0.04

ψ > 500 kPa

−1.23(w^0.56 + T^0.19) + 16.48