Influence of Multistage Target Temperature and Cyclic Loading/Unloading on the Permeability of Polypropylene Fiber Concrete
Table 5
Loss rate of unloading permeability of specimens.
State of stress
Difference of loading-unloading stress ratio (RD)
Permeability loss rate (kP/%)
22°C
40°C
80°C
120°C
160°C
200°C
240°C
280°C
Cyclic nloading process
0.07
1.62
1.73
2.00
2.97
3.43
5.23
6.10
6.25
0.13
2.70
3.46
3.87
4.86
5.44
7.86
8.35
8.70
0.20
4.86
5.19
5.86
6.85
9.61
11.17
12.18
12.43
0.27
6.49
7.36
8.35
9.88
13.47
15.26
16.16
16.36
0.34
8.65
9.96
10.72
12.41
16.16
18.12
18.34
18.90
0.40
10.81
11.69
12.84
15.24
17.76
20.42
21.71
21.77
0.47
11.89
12.99
13.97
16.63
18.69
23.38
23.76
24.65
Single nloading process
0.47
7.57
8.23
9.60
10.49
12.17
16.74
18.77
19.84
Note. The difference between the loading and unloading stress ratio is denoted as RD, which is equal to the difference between the stress ratio Ri and 0.03 at stage I loading.
