$f_t^{*}$ (MPa)

1

1.5

2

2.5

3

3.5

4

${\epsilon }_t\left(\times {10}^{-6}\right)$

65

81

95

107

118

128

137

${\alpha }_t$

0.31

0.7

1.25

1.95

2.81

3.82

5