Temperature limits and precautions for placing concrete in extreme weather. Covers maximum and minimum concrete temperatures at the time of placing, ambient temperature thresholds, and mandatory precautions for hot and cold weather concreting.
Applicable when ambient temperature exceeds 40°C or concrete temperature at placing exceeds 30°C
Condition
Limit
Action Required
Clause
Maximum concrete temperature at placing
40°C (absolute maximum)
Do not place if concrete exceeds 40°C
IS 7861-1 Cl. 5.1
Preferred concrete temperature at placing
≤ 30°C
Use chilled water, ice, or cooled aggregates to bring temperature down
IS 7861-1 Cl. 5.1
Ambient temperature > 40°C
Avoid concreting
Schedule pours during early morning or night; provide shade over batching & placing areas
IS 7861-1 Cl. 4.2
High wind speed (> 25 km/h)
Increased evaporation risk
Erect wind screens around pour area; apply evaporation retarder on surface
IS 7861-1 Cl. 4.3
Low relative humidity (< 40%)
High evaporation rate
Fog spray the area; begin curing immediately after finishing
IS 7861-1 Cl. 4.3
Use of ice in mixing water
Ice must be fully melted before concrete leaves mixer
Add flake ice or crushed ice to mixing water; verify no ice lumps in discharged concrete
IS 7861-1 Cl. 6.2
Transport time in hot weather
≤ 30 minutes from batching to placing
Minimise transit time; cover transit mixer drum with wet hessian if needed
IS 7861-1 Cl. 6.3
Curing in hot weather
Start within 30 minutes of finishing
Ponding, wet hessian, or curing compound; maintain for minimum 14 days
IS 7861-1 Cl. 7
Use of retarding admixture
As per IS 9103
Add retarder to extend setting time by 1–2 hours; adjust dosage for ambient temperature
IS 7861-1 Cl. 6.4
Cold Weather Concreting (IS 7861-2)
Applicable when ambient temperature falls below 5°C or is expected to fall below 0°C within 24 hours
Condition
Limit
Action Required
Clause
Minimum concrete temperature at placing
5°C
Do not place concrete if its temperature is below 5°C at the point of placement
IS 7861-2 Cl. 5.1
Preferred concrete temperature at placing
10°C to 25°C
Heat mixing water (up to 60°C) or aggregates to achieve target temperature
IS 7861-2 Cl. 5.2
Ambient temperature falling below 0°C
Freezing risk — concrete must not freeze within first 24 hours
Provide insulating blankets, heated enclosures, or tarpaulins over fresh concrete
IS 7861-2 Cl. 6.1
Heating mixing water
Max 60°C for water; aggregates max 40°C
Heat water first, then add aggregates, then cement — never add cement to hot water directly
IS 7861-2 Cl. 6.2
Formwork removal in cold weather
Delay stripping until concrete reaches 10 MPa minimum
Test maturity before stripping; use insulated formwork to retain heat
IS 7861-2 Cl. 7.2
Use of accelerating admixture
As per IS 9103; calcium chloride ≤ 2% by weight of cement
Add accelerator to speed hydration; avoid calcium chloride in reinforced concrete
IS 7861-2 Cl. 6.3
Curing in cold weather
Maintain concrete above 10°C for minimum 72 hours
Use curing blankets, heated enclosures, or steam curing; protect from freezing for 7 days
IS 7861-2 Cl. 7.1
General Temperature Limits
Summary of absolute temperature limits for concrete at the time of placing
Condition
Limit
Action Required
Clause
Normal weather placing temperature
15°C to 30°C
No special precautions needed beyond standard practice
IS 456 Cl. 13.1
Absolute maximum at placing
40°C
Reject if exceeded — cool concrete before placing
IS 7861-1 Cl. 5.1
Absolute minimum at placing
5°C
Reject if below — heat ingredients before mixing
IS 7861-2 Cl. 5.1
Temperature differential in mass concrete
≤ 20°C between core and surface
Use low-heat cement, pipe cooling, or pour in smaller lifts
IS 456 Cl. 13.6
Evaporation rate threshold
> 1.0 kg/m²/hr
Take precautions against plastic shrinkage cracking — fog spray, wind screens, evaporation retarder
IS 7861-1 Cl. 4.3
Notes
• Use the evaporation rate calculator (ACI 308 nomograph) combining ambient temperature, concrete temperature, relative humidity, and wind speed to decide precautions.
• Retarding admixtures (IS 9103 Type B) are strongly recommended when placing in temperatures above 35°C to maintain workability.
• In cold weather, never use antifreeze compounds as a substitute for proper temperature maintenance — they are unreliable and not permitted by IS codes.
• Mass concrete (sections > 1 m thick) requires separate thermal control planning regardless of ambient temperature.
• All temperature readings should be taken at the point of discharge into formwork, not at the batching plant.
• Maintain temperature logs for every pour as part of the quality control records.