Temperature Control Measures and Temperature Stress of Mass Concrete during Construction Period in High-Altitude Regions
Table 3
Temperature control schemes.
Temperature control measures for concrete
Scheme 1
Scheme 2
Scheme 3
Scheme 4
Pouring temperature (°C)
Strongly restrained zone
≤12
≤14
≤12
≤12
Weakly restrained zone
≤13
≤15
≤13
≤13
Unrestrained zone
≤14
≤16
≤14
≤14
Simultaneous cooling (m)
Initial stage of simultaneous cooling
Midphase
Midphase
Midphase + phase II
Midphase
Height of the simultaneous cooling zone (m)
27
27
27 + 18
18
Spacing between water pipes (m)
Strongly restrained zone
1.5 × 1.5
1.5 × 1.5
1.5 × 1.5
1.5 × 1.5
Weakly restrained zone
1.5 × 3.0
1.5 × 3.0
1.5 × 3.0
1.5 × 3.0
Unrestrained zone
1.5 × 3.0
1.5 × 3.0
1.5 × 3.0
1.5 × 3.0
Pipe cooling
Phase I cooling
Water temperature (°C)
8.0
8.0
8.0
8.0
Flow rate (m³·h−1)
1.5
1.5
1.5
1.5
Initial flood period (day)
0.0
0.0
0.0
0.0
Target temperature (°C)
19–20
19–20
19–20
19–20
Midphase cooling
Water temperature (°C)
12
12
12
12
Flow rate (m³·h−1)
0.8
0.8
0.8
0.8
Initial flood period (day)
30–45
30–45
30–45
30–45
Target temperature (°C)
16–18
16–18
16–18
16–18
Phase II cooling
Water temperature (°C)
6–8
6–8
6–8
6–8
Flow rate (m³·h−1)
1.0
1.0
1.0
1.0
Initial flood period (day)
≥90
≥90
≥90
≥90
Target temperature (°C)
10
10
10
10
Thickness of poured layers (m)
Strongly restrained zone
1.5
1.5
1.5
1.5
Weakly restrained zone
3.0
3.0
3.0
3.0
Unrestrained zone
3.0
3.0
3.0
3.0
Intermittent period (day)
10
10
10
10
Surface heat preservation
Yes
Yes
Yes
Yes
Note. (1) By the end of Phase I cooling, the temperature is controlled until midphase cooling begins. Once the target temperature in midphase cooling is reached, the temperature is controlled until Phase II cooling is initiated. (2) The temperature drop rate of Phase I cooling is less than 0.5°C·day−1, whereas that of midphase cooling is less than 0.3°C·day−1. (3) When the concrete is poured in winter, the pouring temperature should be greater than 6°C. (4) The midphase + Phase II scheme suggests that simultaneous cooling height of 27 m begins in midphase, whereas that height of 18 m starts in Phase II.
