Temperature has a significant impact on how quickly concrete sets. At Express Concrete, we’ve been supplying ready mix concrete throughout London since 1991, and we’ve seen how different weather conditions affect concrete performance.
Understanding Concrete Setting
Concrete sets through a process called hydration – the chemical reaction between cement and water. This reaction is sensitive to temperature. Just as food cooks at different rates depending on oven temperature, concrete sets faster in warm conditions and slower in cold ones.
Cold Weather Challenges
When temperatures drop below 5°C, concrete faces several challenges:
- The setting process slows down considerably
- Strength development takes longer
- There’s a risk of damage if the concrete freezes before gaining enough strength
Research from the Concrete Society confirms that concrete needs to stay above 5°C until it reaches sufficient strength.
If you’re working with ready mix concrete during colder months, consider these solutions:
- Use heated concrete mixes
- Remove all ice and snow from the work area
- Cover freshly poured concrete with insulating materials
- Add accelerator admixtures that help speed up the setting process
Hot Weather Challenges
High temperatures (above 30°C) create different issues:
- Concrete may begin to harden before you’ve finished working with it
- The mix requires more water to stay workable, which can reduce strength
- There’s an increased risk of cracking as the concrete cools
- Long-term strength may be lower than concrete cured at moderate temperatures
When working in hot conditions, try these approaches:
- Schedule concrete pouring for cooler times of day
- Use chilled water in the concrete mix
- Add retarding admixtures to slow down the setting time
- Keep the concrete moist during curing
Optimal Temperature Range
The ideal temperature for working with concrete is between 10°C and 21°C.
| Temperature Range | Setting Time | Effects on Concrete |
|---|---|---|
| Below 5°C | Very slow | Potential freezing; delayed strength gain |
| 5-10°C | Slow | Extended working time |
| 10-21°C | Moderate | Ideal working conditions |
| 21-30°C | Fast | Reduced working time |
| Above 30°C | Very fast | Difficult to finish; potential cracking |
How Express Concrete Helps
At Express Concrete, we help you manage temperature-related challenges by:
- Monitoring weather forecasts before deliveries
- Adjusting concrete mixes based on expected conditions
- Providing practical advice for your specific situation
- Offering appropriate admixtures to control setting time
Frequently Asked Questions
How long does ready mix concrete take to set?
Under normal conditions (around 20°C), concrete typically takes 2-4 hours to set initially. This can vary from just 1 hour in very hot weather to 8+ hours in cold conditions. Complete curing to full strength occurs over approximately 28 days.
Can I pour concrete if it’s going to freeze overnight?
It’s best to avoid pouring concrete if temperatures will drop below freezing within 24 hours. If necessary, use insulating covers or heated enclosures, and consult with your concrete supplier for specific recommendations.
Will rain damage freshly poured concrete?
Light rain won’t significantly damage concrete that has begun to set. However, heavy rain on fresh concrete can weaken the surface. Keep plastic sheeting available to protect your pour if rain is forecast.
How can I slow down concrete setting in very hot weather?
To slow setting in hot conditions, you can use retarding admixtures, schedule early morning pours, keep equipment cool, and dampen the ground before pouring.
Conclusion
Temperature plays a crucial role in concrete setting times and strength development. By understanding these effects and planning accordingly, you can achieve better results with your concrete projects regardless of weather conditions.
At Express Concrete, we provide quality ready mix concrete and the expertise to help you work successfully in any temperature. Contact us today for your next project!