CON/General/TBT-CON-036
Mass Concrete Pour Temperature Management
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Toolbox Talk
Mass Concrete Pour Temperature Management
Mass concrete pours generate significant heat during cement hydration. If the temperature differential between the core and the surface exceeds safe limits, thermal cracking occurs which compromises structural integrity. Managing temperature during and after the pour requires careful mix design, insulation, and monitoring. This talk covers the controls for temperature management during mass concrete operations.
Key Hazards
Thermal cracking from excessive temperature differential between core and surface
Delayed ettringite formation from peak temperatures exceeding 70°C in the core
Concrete burns from prolonged contact with fresh mix during extended pour durations
Fatigue and error during long continuous pours stretching over 12 or more hours
Control Measures
- Use a low-heat cement blend or include GGBS or PFA to reduce peak hydration temperatures.
- Install temperature monitoring thermocouples at the core, mid-depth, and surface before the pour.
- Record temperature readings at the intervals specified by the concrete technologist throughout curing.
- Apply insulation blankets or formwork lagging to control the rate of heat loss from the surface.
- Ensure the temperature differential between core and surface does not exceed the design limit.
- Coordinate concrete deliveries to maintain a continuous pour without cold joints or interruptions.
- Brief the pour team on the expected duration, shift rotation plan, and temperature monitoring duties.
- Wear alkali-resistant gloves and eye protection throughout the entire pour operation.
- Provide welfare facilities and rest breaks for operatives during pours exceeding standard shift length.
Remember
- Use low-heat cement or supplementary materials to reduce peak hydration temperatures
- Install temperature thermocouples at core, mid-depth, and surface locations before the pour
- Record temperature readings at the specified intervals throughout the entire curing period
- Apply insulation to control heat loss and keep the core-to-surface differential within design limits
- Coordinate deliveries to maintain a continuous pour without cold joints or interruptions
- Provide welfare and rest breaks for operatives during pours that exceed standard shift length
Applicable Legislation: CDM Regulations 2015 · BS EN 13670 (Execution of Concrete Structures) · BS 8500 (Concrete Specification) · Health and Safety at Work etc. Act 1974
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