Why Rain Doesn’t Have to Ruin Your Concrete Pour
Can you mix concrete in the rain? Water is an essential ingredient in concrete, but too much of it is a disaster. When it rains, the water-to-cement ratio is put at risk, potentially leading to a weak surface and cracking.
For Custom Concrete, rain is a challenge we can work with. Because we use volumetric mixers, we don’t batch your concrete until we arrive. If the ground is wet or the sky is grey, our operators can tweak the slump immediately, ensuring your concrete creates a durable, high-strength finish in spite of of the drizzle.
Understanding The Impact of Rain
Rain can affect the concrete mix in a few ways:
- Reduced Strength – Excess water can dilute the cement, leading to a weaker overall concrete.
- Surface Issues – Rain can wash away the cement paste near the surface, creating a weaker and more uneven finish.
- Workability Problems – Heavy rain can make the concrete mix too soupy, making it difficult to place and finish properly.
The Advantage of Volumetric Mixing
Because we do our mixing on-site, the volumetric truck operator can reduce the water-to-cement ratio instantly if it starts raining, which is why Custom Concrete is the safer choice for pouring the British weather.
If the weather forecast predicts very wet conditions, however, we recommend rescheduling your volumetric concrete delivery for a drier day.
Rain Delay? Your Step-by-Step Guide
With volumetric concrete, the good news is that the mixing happens on-site, in the volumetric trucks and is completely insulated from the weather. The challenge is to protect the mixed concrete during transportation to the site of the pour and pouring. Ideally, this should be done as quickly as possible after the mixing, to achieve the full benefit of the fresh concrete.
Here’s what to do:
Before Delivery
Prep Your Site – If rain is forecast, cover the area where you’ll pour the concrete with plastic sheeting or tarps before it starts. This will help keep the ground dry for when the concrete is poured.
During Delivery & Pour
- Use a Concrete Pump for Transport (Optional) – Consider using a concrete pump to transport the mixed concrete from the volumetric truck to the pouring site. This can help minimise the amount of time the concrete is exposed to the rain and reduces the need for manual movement with wheelbarrows.
- Be Ready to Cover Up – Have extra tarps, plastic sheeting, and timber on hand so you can quickly build a temporary shelter if it starts to rain during the pour.
- The Golden Rule – Stop Finishing – If it rains while pouring, DO NOT use a float or trowel to work the water into the surface. This weakens the top layer. Cover it and wait for the rain to stop.
- Avoid Excess Water – If you’re pouring after a rain shower, ensure there is no standing water on the surface where the concrete will go. You don’t want the water mixing with the fresh concrete.
After the Pour
Protection – If possible, keep the newly poured concrete covered for a while to give it a chance to set without being too exposed to excess rain.
Spotting the Signs – Has Rain Damaged My Concrete?
After your concrete has been poured and has had the chance to cure initially, it’s important to check for signs of rain damage. Here are some things to look out for:
- Surface Flaws – Look for pitting, unevenness, scaling, or a dusty surface. These can indicate that rain washed away some of the cement paste during the early stages of curing.
- Cracks and Fissures – While some minor cracking is normal during curing, excessive cracking or wider fissures could be a sign of weakened concrete due to rain exposure.
- Soft or Chalky Texture – Run your finger or a hard object gently over the concrete. If it feels soft or crumbles easily, then the rain likely compromised the mix.
What if I find damage?
Often, surface imperfections caused by rain can be fixed through resurfacing or application of sealers. If the concrete’s structural integrity is compromised, though, you might need to discuss removing and replacing the affected sections with your volumetric concrete supplier or a concrete specialist.
Bear in mind that even if there are no immediate visible signs of damage, rain-affected concrete might be more prone to wear and tear in the future.
Frequently Asked Questions About Wet Weather Concreting
Still have concerns about pouring in the rain? Here are the answers to some of the more specific technical questions we’ve been asked about working in wet weather.
If rain is due immanently, we can add an “accelerator” to the mix on-site. This speeds up the hydration process, helping the concrete set faster so it can be finished and covered before the weather worsens. Ask our team about this when you book.
That’s a big ‘no’. Pouring standard mix into water-filled trenches will cause the cement to separate from the aggregate. You’ll need to pump or bail out standing water before our truck arrives to be sure of a solid foundation.
Only after it has set. Concrete needs moisture to cure properly. Once the surface is hard enough that water won’t mark it (usually after 4–8 hours), gentle rainfall actually helps the curing process and stops cracks caused by drying out too quickly.
We would recommend you keep the plastic covering on until the rain stops and the surface is hard to the touch. If you remove it too early while it’s still raining, you may get surface damage. Check under the plastic now and then to make sure water isn’t pooling and causing dents.
Working with Custom Concrete – Your Hassle-Free Concrete Solution
Custom Concrete is your trusted partner for fresh concrete delivery in Bedfordshire, Hertfordshire, and Buckinghamshire. We’re committed to making your concrete projects a success, even in unpredictable weather!
Here’s what sets us apart:
- Accurate Calculations, No Waste – Our Custom Concrete Calculator takes the guesswork out of ordering – you’ll know exactly how much concrete you need, saving you money and reducing environmental impact.
- Perfect Mix, Every Time – We’ll create the ideal concrete mix for your project, with on-site adjustments possible to handle changing weather or site conditions.
- Freshness Guaranteed – Our on-site mixing means your concrete arrives fresh and ready to use. We’ll deliver it right when you need it.
- Need a Pump? We’ve Got You Covered – We offer concrete pump hire and can advise if your project would benefit from one.
- Expert Advice – Our knowledgeable customer service team can answer all your concrete questions, from mix types to weather impact and ideal pouring conditions.
Ready for a smoother concrete experience? Contact Custom Concrete today for a free quote and experience the difference of fresh, on-site mixed concrete!