Back before radar made it possible to predict the weather with a decent degree of accuracy, construction contractors simply held out hope that their fresh concrete would not be affected by sudden rains. Even with today’s weather prediction technology, it isn’t always possible to escape sudden downpours after pouring fresh concrete, though.
As such, it is important for all contractors to know how to deal with rain on their new concrete slabs.
This guide will take you through what you need to know on that front, including the varied effects of rain on concrete. Herein, you’ll also learn a few tips for pouring concrete in rain as well as assessing any damage endured by your new slab after a downpour.
Rain’s Effects on Concrete
As you already know, water is just one of several vital ingredients in a concrete mixture.
As such, only a very specific amount is meant to go into a mixture to ensure that the final product is as durable as desired. Any less (or in this case, more) and that mixture ratio will be thrown off, resulting in potential issues for the long-term stability of your new structure.
The biggest risk to your concrete exists within its first 2 hours of placement.
If rain rolls in during that period, too much water may make its way into the still-wet concrete mixture. While this may not be an issue at first, this could eventually result in a weaker internal concrete structure. Surface scaling is also possible once this overly-wet mixture dries.
However, depending on what sealants were used in your concrete, your new slab may be protected at the surface level as soon as 2-4 hours after pouring it. However, this is only likely to occur if the concrete in question received strong sunlight prior to the rain’s arrival.
Otherwise, within 4-8 hours, your new concrete should be fully safe from damage caused by sudden rains.
Can You Pour Concrete in Rain?
Generally speaking, you should avoid pouring concrete in the rain.
This is simply for safety reasons, as a wet worksite is always more dangerous for you and your crew. Also, achieving an optimal concrete mixture will be much harder when you can’t control how much rain is getting into it.
In the same vein, you should never pour concrete or perform any job site work with a thunderstorm in the area.
However, if the rain in your area is light and you are practicing extra care around the job site, you may be able to pour concrete.
Continue reading below for some tips on how to do that successfully.
3 Tips to Pour Concrete in Rain Successfully
If an upcoming contracting job will require you to pour some or all of your concrete in the rain, then be sure to keep these following tips in mind. Though they won’t spell absolute success, they can help your team get the best results out of your concrete, despite the circumstances.
Always plan ahead: Whenever possible, check weather forecasts for the region where you’ll be working. If rain is in the forecast, you should postpone any concrete pouring if your schedule allows for it. This will ensure that, when you are able to pour your concrete, it is given the best conditions in which to dry and cure.
Bring plastic sheeting: Regardless of the expected weather on the day you’re pouring concrete, be sure to bring along some industrial plastic sheeting. If an unexpected rainstorm rolls in, you’ll be able to use it to protect the surface of any freshly-poured concrete.
Be prepared to assess: If a rainstorm does take your crew by surprise, they should be prepared to examine their fresh concrete as soon as the storm subsides. In particular, they will need to assess for surface and interior damage caused by the presence of added water during the curing process (see below for more information on this process).
How to Assess If Rain Damaged Your Concrete
After the excess water has been removed from the surface of your new concrete, your team should begin to assess if it has sustained any lasting damage.
To start, perform a scratch test to check the surface strength of the wet slab. If it is comparable to a section of a known sturdy slab, then you should be in the clear.
Also, if you have the resources available, you may want to take some core tests of your new concrete. These cores can be examined in a lab setting to ensure that their structure was not impacted by the introduction of added rainwater.
If you can at all avoid it, you should avoid pouring concrete when rain is expected in your area. But summer showers are bound to occur, thus requiring you to determine the best method for protecting your fresh concrete against the elements.
Hopefully, this guide’s information will enable you to adequately maintain your concrete’s integrity, even when mother nature gets in the way.