Concrete Curing Time

pouring concrete

Waiting for the curing of concrete can easily test patience, especially when you’re ready to move on to the next step of a project. However, it’s important to remember that quality is the end goal, not quickness. Rushing ahead and not allowing enough time for concrete to properly cure before allowing foot traffic or heavy machinery to travel across your newly placed cement can seriously compromise the integrity of a concrete slab.

 

Cement Curing Factors

Several factors influence concrete slab cure time, including:

 

Typical Concrete Setting Time

Typically, concrete is recognized to have reached full strength 28 days after placement; however, this does not mean you need to wait 28 days to walk, or even continue construction on newly placed concrete. After placement, concrete increases in strength very quickly for 3-7 days, then gradually for the next 3 weeks. This means that concrete hardening time is typically 24-48 hours, at which point it’s safe for normal foot traffic. After one week, concrete is typically cured enough to handle continued construction including heavy machinery.

concrete curing time

The “70 in 7” Rule

When in doubt, remember the “70 in 7” rule: Most concrete mixes will have reached 70% of specified compressive strength after 7 days. At this point, it’s ready for exposure to normal traffic.

concrete curing blanket

Concrete Curing Blankets

Unfortunately, cold weather during winter months can seriously slow down concrete cure time and significantly hold up construction projects. The best temperature to cure concrete is above 5o°F, which can be difficult to replicate if the air is below freezing.

Luckily, solutions, such as concrete curing blankets that maintain optimum temperatures during cure time, are available. Concrete Blankets are an effective option that cure concrete 2.8 times faster than a typical insulated blanket and properly maintain moisture throughout the hydrating process. Concrete Blankets are easily transported and installed and maintain ACI compliance for cold-weather concreting. If you’re looking for a solution to maintaining optimum concrete cure time during cold winter, using a Concrete Blanket is the best method for drying and curing concrete.

How Cold is Too Cold to Pour Concrete?

What Temperature is Too Cold to Pour Concrete?

Experts agree that the best temperature to pour concrete is between 50-60 °F. The necessary chemical reactions that set and strengthen concrete slow significantly below 50 °F and are almost non-existent below 40 °F. Even when daytime temperatures are within the satisfactory range, winter concrete setting creates risks that could result in weak, inadequate concrete. If nighttime temperatures are below freezing, the water in the concrete will freeze and expand, causing cracks. Additionally, if temperatures reach below 40 °F (but not freezing) during set time, concrete will take much longer to reach required strength. However, if the correct measures are taken, concrete can still be successfully placed during even the coldest months of the year.

Things to Consider with Cold Weather Concreting

Before embarking on a cold weather concrete project, it’s important to determine any special strength requirements or considerations. This will help as you schedule your pouring and determine which strategies you will use to keep your surroundings and materials warm. The predominant challenge you will face during a winter concrete project is ensuring that the concrete sets before it is exposed to freezing temperatures. You might take the following suggestions into consideration as you plan your upcoming project:

  • Use heaters to thaw frozen ground, snow or ice.
  • Use hot water to mix cement.
  • Keep dry materials in a dry, warm location.
  • Use products designed to set quickly. During cold weather, these products will not set as quickly as the instructions may indicate, but will set faster than conventional materials.
  • Use additives that accelerate set time. Use caution; if additives contain calcium chloride, any rebar or metal wire mesh in concrete will rust and cause concrete to crack.
  • Use extra cement (typically 100 lb/ cubic yard) to make the reaction hotter and cause concrete to hydrate more rapidly.
  • Remember that you still need to wait for bleed water to evaporate. Incorporating the water into the surface during finishing will weaken the surface. Bleeding starts later and takes longer during cold weather; you can use squeegees or a vacuum to remove water quickly.
  • Wait until concrete has reached desired strength to remove any framework. If the framework is removed too early, the concrete will be damaged and the surface could collapse.

Maintaining Ideal Temperature

After implementing the above suggestions, It’s important to consider how you will keep concrete at the correct temperature during the curing process. Concrete must maintain a temperature above 50 °F for approximately 48 hours for the correct chemical reactions to take place. Two popular options used during cold weather concrete curing are heated enclosures and insulated blankets. If using an enclosure, ensure that the structure is both wind and waterproof. Additionally, ensure that there is proper ventilation for the space heater. Heaters cause an increase in carbon dioxide that could cause carbonation in the surface of the concrete.

Powerblanket Concrete Blankets

Powerblanket® concrete blankets are an extremely effective option for attaining and maintaining the correct temperatures for concrete pouring and setting. Powerblanket® concrete blankets can be used to thaw ground before pouring concrete and again after finishing to keep concrete from freezing. Utilizing Powerblanket® concrete blankets will ensure that concrete is kept at the correct temperature for the necessary reactions to happen quickly and the desired strength to be reached.

A Concrete Curing Solution

If you live in the North American Mountain West, or any region where it gets cold during the winter months, chances are you’ve seen chipping concrete. Have you ever stopped to think what causes concrete to chip? Improper curing is what causes it, but with a good concrete curing blanket, this problem can be completely avoided.

 

A Concrete Curing Solution 1

Not All Concrete Curing Blankets Are The Same

If you’ve ever seen chipped concrete before, it’s likely due to cold weather. But we’re not talking about cold weather after the pour. No, chipping concrete often results from it being poured when it was too cold. This means the concrete never fully cured. Thus, it became brittle and flaky. The simple solution to this dilemma is either to wait until its warm enough outside, or else apply a concrete curing blanket.

If you did a search on Google for concrete curing blankets, you’re likely to find a myriad of options. But not all these options are the same. A good majority of the curing blankets out there are merely insulation blankets. Now insulation is a good thing to have in a curing solution, but it’s only half of the equation. The problem with simply insulating the concrete is twofold.

If you have a concrete blanket that only acts as an insulator then it’s not likely to help in the extreme weather. This is the first problem with an insulation blanket. The second is this: with only insulation on your side, you’re not going to be speeding up the curing process at all. When concrete cures, a chemical reaction occurs. This reaction causes the concrete to put off heat. With this in mind, placing an insulated blanket over the concrete will help to keep some of this heat in, but the amount of heat it will trap isn’t substantial enough to help cure concrete in really cold weather, or to speed up the curing process much either.

 

A Concrete Curing Solution 2

The Real Solution is Electric

This is why you need an electric curing blanket, or a heated curing blanket, to get the job done right. Electric curing blankets will both insulate and heat the concrete to an ideal temperature for curing. With the characteristics of a heated blanket at play, you can properly cure concrete in very cold temperatures. What’s more, even if the weather isn’t that bad, you can apply such a solution to speed up the curing process by leaps and bounds.

When it comes to picking the best electric curing blanket, there are a few major aspects to be concerned with. Number one, you want to make sure you get a blanket that will evenly distribute the heat throughout the entire application area. If the blanket is hotter in some places than others, you’re not going to get an even cure. Number two, you want to make sure you get a product that is properly certified for safety and efficiency. And number three, you want to make certain you purchase a blanket that can regulate its own heat. A blanket with a thermostatic controller will enable you to apply the heat and walk away without worrying whether it will keep consistent heat for the whole time you’re curing.

 

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The Wonders of Concrete: From Creativity to Concrete Curing

When most people think about concrete, their minds quickly turn to the common, grey, lifeless slabs that we walk and drive on. You can’t fault anyone for envisioning concrete in this way, but is it really a fair representation of such a versatile and varied construction material? We don’t think so. From creativity to curing, concrete is a truly amazing product.

 

The Wonders of Concrete- From Creativity to Concrete Curing 1

Concrete’s Real Potential

If you’re one of the individuals whose thoughts turn to sidewalks, interstates, overpasses, and patios when you hear the word concrete, well, it’s really to be expected. These forms of concrete application are certainly the most common. But there are also many other common uses that the typical person may not been clued in to.

Instead of settling on the usual image of concrete, take a chance to expand your horizon. Have you ever stopped to think about the many different types of pavement that exist? The fact of the matter is that much of the pavement you’ve seen, both indoor and outdoor, is some form of concrete. You see, concrete has possibilities for design that many people never even stop to consider.

 

The Wonders of Concrete- From Creativity to Concrete Curing 2

Decorative Concrete

For those in the know, concrete that falls outside of the stereotypical application and image is known as decorative concrete. And what some people have been able to do with decorative concrete is simply amazing.

Take for example the patterns that skilled concrete layers have been able to weave into what would otherwise be a very boring driveway. Perhaps you’ve seen the same techniques employed in outdoor walkways in and around historic downtown districts, malls, or river walks. Think of the innumerable possibilities that exist with such a method. Think of this, and you’ve only scratched the surface, though.

Even with as many outdoor uses concrete has, there are just as many indoor application methods. In fact, these types are the most stunning. Take a look at the picture below the driveway. Looks like tile; doesn’t it? Nope, it’s concrete, decorative concrete that has been designed to look like a very impressive tile pattern. Now take a look at the image below that. Looks like laminate wood flooring; doesn’t it? Actually, it’s concrete too.

This sort of thing is quite the surprise; isn’t it? For those who first venture into the realm of decorative concrete, the possibilities at first seem almost unbelievable. Oh, but they’re a very real and valuable way to make expanded use of one of the world’s most common construction products. To find more great examples of concrete usage, just type into Google: “decorative concrete” (under an images search).

 

Powerblanket and Concrete

If you’re in the concrete business, then you know how much freezing temperatures are an enemy to concrete curing. Well, whether you’re pouring concrete to create the usual, grey slab of strong and reliable stuff or your working concrete into a work of art, Powerblanket has you covered.

With Powerblanket® Concrete Curing Blankets, you can ensure the proper and ideal curing of concrete even in freezing conditions. You’ve never pour concrete in the cold? Well, how would you like your curing process to go nearly three times faster? In either occasion, Powerblanket can help.

 

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The Cure for the Common Cold Concrete

If you’ve ever had to lay concrete in the cold, then you can attest to the fact that it doesn’t set up as fast as it aught too. Actually, inclement weather can delay the curing of concrete considerably.

 

Heating Mortar Ingredients for Cold Concrete Weather Masonry

The Cure

When it comes to curing concrete, the optimal temperature is easy to obtain most of the time…if it’s summer. But what about all the other months of the year? What do you do when winter rolls around? More often than not, winter will put a screeching halt on the progress of temperature-sensitive construction projects, and concrete is one such example.

When concrete is subjected to cold weather, the time is takes to adequately cure increases significantly. According to the Portland Cement Association (PCA), “compression strength of concrete cured at 50 degrees Fahrenheit is expected is expected to gain strength half as quickly as concrete cured at 73 degrees Fahrenheit,” (PCA). So how do you speed up the process?

 

Insulation or Heat Application

A long standing-tradition for protecting concrete against the cold is to apply insulation to the concrete after it is hard enough to maintain its form under the weight of an insulation blanket. While this helps to keep the concrete from dropping in temperature drastically, it does nothing to bring the cement to an ideal temperature. However, there is an option that does this very thing.

Along with insulation blankets, there are concrete curing blankets.Concrete curing blankets not only help to insulate concrete against the cold, but they also help to raise its temperature and that of the ambient air around it. Done right, concrete curing blankets can be dialed in to a certain temperature and left to do the job without monitoring.

 

PCA

http://www.cement.org/for-concrete-books-learning/concrete-technology/concrete-construction/curing-in-construction   

See all the details of the Powerblanket® concrete curing blanket by downloading the free product spec sheet!

 

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