Pouring Fresh Concrete in the Rain

Are you considering pouring fresh concrete, but Mother Nature has other plans? The good news is you can pour it. Before you get started, consider taking a few precautionary steps. 
Whether you're a new contractor or a seasoned pro, we've got you covered. Discover how to protect your fresh concrete investment and ensure a successful project even when the raindrops start falling. 

If you're preparing to pour concrete, one critical factor to consider is current weather conditions. Rain, in particular, can affect the outcome of your concrete project. Rain intensity is key. Here's how light, moderate, and heavy rain can impact fresh concrete: 

Light rain or drizzle typically poses minimal risk to fresh concrete. A little drizzle can sometimes be beneficial as it helps support a moist curing environment, which aids in concrete strength development. 

Moderate rain can cause concern. Raindrops can displace the surface mortar. When that happens, you can discover surface defects and a weakened top layer. To counteract this, use protective measures, such as concrete coverings. 

Heavy rain is the most problematic for fresh concrete. The sheer volume of excess water can lead to surface erosion, washout of cement fines, and even complete structural failure. Avoid pouring concrete during heavy rain whenever possible. 

We cannot stress enough how critical it is to check weather forecasts when planning a concrete pour. Here's why:

Weather forecasts allow you to schedule your concrete pour during periods of expected dry weather. This proactive approach reduces the risk of rain interfering with the curing and finishing processes. 

Forecasts provide insights into the likelihood and potential intensity of rain. Armed with this information, you can make informed decisions. You might consider postponing the pour based on the forecast. 

By staying informed about upcoming weather conditions, you'll have time to prepare your site. This includes having the necessary covers, equipment, and personnel ready to protect the concrete in case of unexpected rain. 

Never underestimate the impact of weather conditions on fresh concrete. Light rain may have minimal effects, but moderate to heavy rain can lead to rain-damaged concrete. 

Selecting the right concrete mix is a pivotal decision when you're pouring fresh concrete, especially when rain is a potential factor. It's not only the concrete you choose, but you'll want to know which additives can enhance its resistance to rain. 

Different concrete mixes have varying strength and durability characteristics. It's essential to assess your project's requirements and choose a mix that aligns with them. A self-consolidating concrete can withstand many of the challenges associated with rain. 

The water-cement ratio in a concrete mix influences its vulnerability to rain. A lower water-cement ratio results in denser, more impermeable concrete. It also prevents the pooling of surface water on top of concrete. 

The type and quality of aggregates in the mix can affect its resistance to rain. Well-graded, clean, and angular aggregates contribute to better cohesion. They reduce vulnerability to erosion caused by rain. 

After placing the concrete, use curing compounds that form a moisture-retaining film on the surface. This can protect the concrete from rainwater, helping it achieve optimal strength and durability.  Whether you go with a wet concrete or dry cement mix, choosing the right concrete mix is necessary to ensure the longevity and performance of your project.

 
Choosing the right mix can also prevent surface scaling, an issue associated with freeze-thaw cycles. A dry cement mix helps reduce waste and works well in rain-prone climates.

Pouring concrete on wet ground presents some unique challenges. Under certain conditions, you can go ahead and pour. We suggest taking precautions to prepare the ground to support the concrete. Make sure to have proper drainage. You may need to first improve drainage in the area. Direct water away from the work area, and if necessary, install drainage systems or use gravel or crushed stone to create a well-draining base. 

Make sure you have a dry and stable subgrade. Wet and unstable subgrade can lead to settlement, cracking, or uneven curing. Adequate compaction of the subgrade is essential to prevent settling and unevenness. There are other considerations, so it's wise to consult with a concrete contractor or engineer with experience in working on wet ground. 

When rain threatens your pour, cover the concrete. It sounds simplistic, but it's vital. You have a choice of temporary covers that work well to protect the surface of the concrete. They include: 

Plastic sheets are an effective way to shield fresh concrete from rain. They're cost-effective, easy to work with, and readily available. Choose heavy-duty, UV-resistant sheets for better durability. 

Polyethylene tarps used to be the preferred material for protecting concrete. Insulated tarps are better because they help maintain a consistent temperature, which can speed up the curing process. Even if it's already started raining, make the effort to cover the wet concrete. 

Properly curing fresh concrete is essential for its long-term strength and durability. In rainy conditions, the curing process becomes even more critical. You have three primary options for curing concrete in the rain. 

Wet curing involves keeping the concrete surface consistently moist. This method can be particularly effective in rainy conditions.

Curing compounds are liquid coatings applied to the concrete surface to retain moisture. Curing compounds work well when rain is intermittent. 

Cover the concrete with wet materials like burlap, sand, or straw. These materials hold moisture against the concrete surface, aiding in the curing process. 

Fresh concrete and rain. These two words don't need to mean canceling a pour. By watching the weather forecasts and planning well, you can still complete your project. Whether you need solutions for curing concrete or forming accessories, Deslauriers has an entire catalog of products geared toward concrete professionals. Check out our online catalog or reach out to our team for assistance with our products.