No. It reduces strength. Ask for a retarder or water reducer when ordering instead.
Hot-Weather Concreting.
Heat, sun and wind speed up setting and dry the surface fast. Plan ahead and you can pour in summer without losing strength or finish.
At a glance:
25°C+ : When hot-weather measures apply
1.0 kg/m²/h : Evaporation rate that needs protection
Early start : Best pour time
What Heat Does to Concrete.
High temperatures speed up hydration. Concrete stiffens sooner, leaving less time to place and finish. Wind and low humidity pull water from the surface, causing plastic shrinkage cracks. Hot concrete can also reach lower long-term strength.
During & After.
Place and finish without delay. Use wind breaks or sunshades where possible. If the surface starts drying before finishing, use an evaporation retarder, not water.
Start curing immediately. Hot, dry weather is when curing matters most. Keep new concrete continuously moist for at least 7 days.
Before the Pour:
Schedule early: Pour in the early morning, when it's coolest.
Ask for a retarder: It extends working time. Tell us the forecast when you book.
Dampen the base and forms: A dry subgrade draws water out of the concrete. Avoid standing water.
Have crew and tools ready: Delays cost more when setting time is short.
Frequently Asked Questions
Can I add water if the concrete is stiffening?
What's an evaporation retarder?
A spray-on film that slows moisture loss from the surface between finishing passes. It is not a curing compound.
What causes small surface cracks on hot days?
Usually plastic shrinkage, when the surface dries faster than bleed water can replace it.
Should I pour in the afternoon?
Avoid it in hot weather. Early morning is safer.
Does hot weather affect admixture choice?
Yes. Retarders and water reducers are common in summer. We'll recommend a mix for the forecast.
Disclaimer: These guides are general information. Always follow your engineer's specification and local building requirements.
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