How Do Weather Conditions Affect a Site Mixed Concrete Pour?
Previously we have discussed the advantages associated the use of volumetric concrete trucks which deliver the raw materials and provide fresh site mixed concrete exactly where it is needed. We’re often asked what impact the weather has on this process, though? Are there ideal weather conditions for pouring concrete? And will hot, cold or rainy weather affect the quality?
In this article, the Custom Concrete team offers guidance on the impact of rain, cold or heat on concrete mixing, pouring, and curing. We’ll also consider ways to deal with these issues in order to maintain the quality and strength of your concrete mix.
Pouring Concrete in Hot Weather
The temperate climate we experience across the UK delivers, for most of the year, the ideal weather conditions for pouring concrete. More recently, though, summer temperatures have been higher than normal, and it is certainly worth avoiding a concrete pour on days when the temperature is hovering around 30°C.
Concrete begins to cure as soon as it is poured. High temperatures can accelerate the evaporation of moisture in the concrete, which means the mix won’t hydrate adequately. Concrete requires hydration in order to form the crystals which makes the concrete strong. There is also the risk that water will evaporate on the surface too fast, which could lead to cracking and shrinkage.
Ways to Manage Pouring Concrete in Hot Weather:
- Try to avoid the hours 11am-3pm for pouring concrete in hot conditions.
- Cover poured concrete with a plastic sheet to prevent evaporation.
- Make sure you have adequate people available to lay the concrete fast.
Pouring Concrete in Cold Weather
NHBC standards require temperatures to be above 2°C for mixing and pouring site-mixed concrete. Temperatures lower than this can impact on chemical reactions that occur as part of the curing process, and there is a risk of ice forming in the concrete mix. This reduces the strength of the concrete and severely slows down the curing process.
In temperatures between 2- 5ºC, concrete is unlikely to be damaged but it will take longer to strengthen and set. It’s advisable, therefore, not to remove formwork until you are certain that it is safe to do so, in order to avoid corners being misshapen.
Ways to Manage Pouring Concrete in Cold Weather:
- Do not pour concrete into frozen or frosty ground.
- Leave formwork in place for longer as the concrete requires more time to set.
- A concrete curing blanket will help the concrete to cure in cold weather.
A Concrete Pour in the Rain
At Custom Concrete we take great care to provide the correct concrete mix for the job that needs doing. If that concrete mix is then poured into trenches soaked with rainwater, this adds more moisture to the mix and could lead to issues such as weak concrete and cracking as a result of shrinkage. Equally problematic is rain falling onto concrete whilst it is curing.
Site mixed concrete offers the benefit of being able to tweak the mix according to the weather conditions we’re working in. Every member of our team is experienced in dealing with a range of weather conditions for pouring concrete and can offer guidance based on that experience.
- Avoid pouring concrete on wet surfaces or accumulated water.
- Check the weather forecast and avoid pouring when heavy rain is expected.
- Cover the concrete after pouring to avoid rain washing away the surface.
- Ensure that any water accumulating onsite drains away efficiently.
Working With Custom Concrete
The Custom Concrete team has an expert understanding of the impact weather conditions for pouring concrete can have on the success of your project outcome.
We are an independent provider of site mixed concrete to commercial, construction and residential customers in Bedfordshire, Buckinghamshire, and Hertfordshire. The Custom Concrete Calculator allows customers to assess the volume of concrete they require, and we can offer expert guidance on the appropriate mix for the job. All our concrete is mixed fresh, on site, where it is needed.
Would you like to order Custom Concrete fresh, site-mixed concrete? Call us today on 01525 861899 or contact us online.