Concrete Curing in Freezers

Curing concrete in a deep freezer is a unique experience. Walk-in freezers are crucial to any organization that handles temperature sensitive material. The ability to store mass amounts of cold product in a controlled environment allows for meat, ice cream, cadavers, liquid oxygen and more to be used nearly anywhere in the world, so long as there is a freezer to put it in.

Most often, these freezers have a concrete flooring that is specially cured to handle the frozen environment around it, while keeping the heat from nearby room temperatures out. On top of all this, concrete flooring also needs to be able to withstand everything from footsteps to forklifts in ways that mitigate as much repair as possible.

Image taken from www.garonproducts.com

When preparing and pouring cement for freezer floors, there are several steps that one should consider, especially since this isn’t your usual concrete constructing picnic:

  • Maintain the mix: Be sure that your mix of concrete doesn’t contain too much water. Not only is it likely to cause cracking due to shrinkage, but it can also lead to water freezing within the concrete if it’s not cured enough by the time the freezer begins operating.
  • Seal the deal: The United States Dairy Association has a zero-tolerance policy regarding leaks in the freezer space. Frozen food should be stored at 0°F (-18°), as “freezing to 0° F inactivates any microbes — bacteria, yeasts and molds — present in food.” Any leakage would lead to moisture invading the freezer, potentially allowing mold and other harmful bacteria to grow. Any concrete installed as part of a walk-in freezer must be properly set and sealed to prevent leaks from happening.

Restoring Concrete Freezer Floors

With that in mind, you might be wondering how to repair concrete floors in freezers. Damage to the concrete floor like cracking or chipping can happen via forklift accident, replacing glycol heating systems, or subsoil moisture freezing.

Cracking occurs naturally in concrete, and there’s virtually no way to prevent it from ever happening. The best tools for repairing concrete freezer floors are low-temperature grade epoxy seals and additional concrete.

Equally important of what to use is what not to use. Repair product manufacturers like Polycote advocate against hard repair mortar when fixing floor joints. Doing so will create an inflexible bond that will not allow for any concrete movement, increasing the chances of additional concrete cracking.

Things to Keep an Eye Out For

Our friends at Concrete Mender offer several challenges that pose a problem when repairing concrete, which include frost, working conditions, and curing:

  • Frost: Frozen moisture in the concrete will act as a barrier between the repair material and the pores of the concrete. Most repair materials will try to bond to the frost coated concrete. When the temperature increases, the frost melts and so does the bond.
  • Working conditions: Working with materials in the cold is challenging to both man and materials. Mixing epoxies or mortars in the cold is especially challenging. As the temperature decreases, the viscosity and flow rate of these materials increase making them harder to mix and much more difficult to work with. Drum heaters are an excellent solution to keeping epoxy and mortar warm while waiting to use on a freezer job.
  • Curing: With most materials, cure times in cold environments are extended significantly. A product that normally cures in an hour at room temperature may take as much as 12 hours in a cold environment. Some materials may not cure at all before actually freezing solid. Use a concrete curing blanket to help the concrete cure for maximum strength.

If You’re Gonna Do a Job, You’d Better Do It Right

Fixing a freezer is a job you only want to do once. Making crack repairs can be tedious and have to be done exactly to specifications in meeting safety requirements. After all, keeping that freezer sealed tight with a good concrete job will keep the cadavers cold and food frozen.

The best tools to help with a quick, clean concrete repair job are drum heaters and curing blankets. For more information on these items, check out Powerblanket’s concrete solutions.

All About Concrete Cracking Repair

Concrete gets old with age, just like we do. When laid correctly, concrete doesn’t really pose any problems until the cracking and wearing part of the life cycle begins. Concrete cracking happens naturally, but that doesn’t mean you can’t do anything about it. 

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Cracking is a constant in concrete. Nearly every slab of concrete ever laid will feature cracking at some point. This can lead to a series of important questions:

  • What is causing the cracking?
  • Is the structural integrity of my concrete compromised due to cracking?
  • Can cracking be repaired without replacing the concrete?
  • What can be done next time to help mitigate cracking?

Concrete Cracking Causes

The Concrete Network lists five causes of concrete cracking: excess water in concrete mix, rapid drying of concrete, improper strength concrete poured, lack of control joints, and poor ground conditions before pouring.

  1. Excess water in concrete mix: Concrete shrinks as it dries thanks to the water within the concrete mix evaporating. Though water is an important part of the concrete mixture, too much water will create a “soupy” concrete mix. When the water evaporates, the remaining concrete shrinks to maintain its strength. According to the Concrete Network, “concrete slabs can shrink as much as 1/2 inch per 100 feet. This shrinkage causes forces in the concrete which literally pull the slab apart. Cracks are the end result of these forces.”

    The best way to mitigate cracking of this type from happening is to be careful with how much water is added to your concrete mix. A low water-to-cement ratio will go a long way in preventing cracking.
  2. Rapid drying of concrete: Concrete will often not be able to achieve its maximum strength if it cures too fast. Hydration is the chemical reaction that allows the cement mixture to absorb water, changing from a liquid mixture into a solid slab. This process can take days, even weeks to become stiff enough to achieve desired strengths. Using a concrete curing blanket can allow less impact from external variables that affect concrete drying.

    Powerblanket image
  3. Improper strength of concrete poured: Not all cement mixes are created equally. Different mixes suit different purposes. You can bet that the concrete slab you poured to make the kids’ basketball court is a different strength than the Normandy bunkers stormed by the Allies on D-Day. Pouring the wrong strength of concrete can set you up for cracking. Check with your concrete provider to ensure you’re using the right strength of concrete for your project.
  4. Lack of control joints: Control joints let you choose where the cracking occurs. By allowing for spacing between concrete slabs, you can make sure cracks happen in straight lines and don’t spread due to temperature fluctuations and movement.

    Image taken from Concrete Construction Magazine

    When control joints aren’t used, cracking will happen in the most natural way possible with no direction from you. Cutting control joints must be done within 12 hours of pouring concrete, or as soon as the concrete has hardened.

  5. Poor ground conditions: Do not pour concrete on frozen ground. The poured concrete will bind to the ice inside of the frozen soil, and will become unbound once the ice melts. If you have to pour concrete in cold weather conditions, use a ground thawing blanket to get ground surfaces to the right temperature. This will ensure proper joining of ground and cement layers. The ground should also be dry, so make sure you’re not pouring concrete into a puddle or saturated soil.

Cracking Impacts Concrete

Structural integrity is what concrete is all about. Properly evaluating the impact of cracking can help you decide if your structure is sustainable, or if you need to replace that part of the project with another concrete pour. Opting to repair your concrete is feasible only once it’s been confirmed there are no structural issues.

Image taken from www.nextstartech.com

Repairing Cracks

Concrete Construction says that if you’ve noticed cracking in your concrete, you’ll want to follow several steps before taking any repair measures:

“Before repairing your next crack, perform a crack evaluation and establish the repair objectives. Decide what type of repair is needed. Choices include a structural repair using epoxy, a route and seal repair using a flexible sealant to accommodate future crack movements, and a hard or semi-rigid filler repair to support crack edges, with or without routing. Also, establish the cosmetic requirements. After choosing the repair material and procedure, follow the manufacturer’s recommendations.”

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After completing the crack repair, reassess the area to see how you can blend the look of the repair back into the concrete, giving your project a smoother look.

Cracking: It’s Going to Happen

Though repairing cracking will allow for longer-lasting strength for your concrete, mitigating excessive cracking from happening in the first place is best. It can’t be stopped, but it can be controlled. Refer to the above guide next time you’re on a concrete job to make sure you have all your concrete cracking bases covered.

Check out Powerblanket’s concrete solutions here.

How to Stain Concrete: Stain your way from gloom to glam

Let’s get one thing straight. Plain, gray concrete is best used in military bunkers. Other than that, it’s downright boring. What can you do to spice up your concrete patio, concrete counter-tops, and concrete floors? There’s one solution: stain it. Staining concrete takes time and effort, but the results are beautiful.

Image taken from www.thatisconcrete.com.

Types of Concrete Stain

If you’re a parent, the word “stain” probably doesn’t make you think of something beautiful or decorative. Nonetheless, concrete staining is a great way to turn a slab of gray into luxurious concrete with color or shine. Concrete experts generally use one of two ways to stain concrete: acid and water-based stains. Each one has a specific purpose, but which one should you use?

Acid Concrete Stains

  • Acid stains are made up of metallic salt minerals dissolved into a water-acid mixture. The acid causes a chemical reaction during the curing process that permanently changes the concrete surface color and texture.
Acid stained porch in Colorado. Image taken from www.denverconcretecompany.net.

Non-Acid Concrete Stains

  • Non-acid stains treat concrete differently than an acid stain. Instead of altering the structure of the concrete, non-acid stains create a layer over the concrete surface, filling pores and leaving behind a flat, smooth finish.
Non-acid stained concrete. Image taken from www.super-krete.com.

Concrete Staining Process

Do Your Prepwork

According to industry experts, the best way to stain concrete is as follows:

  • Thoroughly clean and prepare concrete
  • Apply concrete stain
  • Clean up and neutralize concrete stain
  • Seal concrete for lasting protection

In order to stain concrete, the concrete must be cured to its proper strength. This can take up to 48 hours, but with concrete curing products, this time can be nearly cut in half. Powerblanket’s Concrete Curing Blanket helps keep concrete at stable temperatures above 50°F, curing 2.8 times faster than open air curing. This is especially helpful when staining concrete in places where temperatures are variable or close to freezing. Make sure your concrete creation cures correctly.

Once it is cured, you can move on to the concrete staining process. Begin washing down the concrete surface. You don’t want any food crumbs or shoe scuff marks to get in the way of the stain, so make sure to give it a good scrub down. Also remove any layers of glue, sealers or curing membranes that might prevent the stain from coming in full contact with the concrete. Finally, apply a concrete acid cleanser to the project surface to ensure the concrete is as porous as possible. Once it has dried, rinse the concrete with water. Some concrete manufacturers, like Quikrete, even make their own cleaners, etchers, and de-greasers so you know you are using the best products on your concrete.

Let The Staining Begin

After the concrete is no longer wet from rinsing, use a brush or roller to spread the stain across the project surface. If it’s a puddle you can splash in (don’t), it’s too thick. If it disappears right after applying it (i.e. it absorbed into the concrete), you need more.

Once your initial layer is down, allow 24 hours of drying before applying another layer of stain, even if it’s the same stain color.

Most concrete stains have difficulty drying in cold temperatures. If you must do a concrete staining project in the dead of winter, a Concrete Curing Blanket can save the day, allowing the stain to dry within a controlled environment.

Protect Your Project

You’re so close to being done! After the stain has dried, use a sealer or wax to protect the stain from dirt or grime that could change the color or texture over time. You’ll need to regularly clean the concrete surface, but don’t use powerful chemicals like bleach, vinegar or ammonia. Such solutions can damage stained concrete. And you wouldn’t want that, would you?

Image taken from www.kronion.pw.

Finally, bask in your work. Enjoy the fruit of your labors and invite friends and family over to see your decoratively stained concrete.

Concrete Solutions From Powerblanket

All successful projects start with a solid foundation.  Concrete Curing Blankets from Powerblanket ensure your pour cures quickly, strongly, and is ready for the next step in your project.  Contact us today to find a solution for your concrete needs 855.440.0208 or [email protected]

What Temperature is Too Cold to Pour Concrete?

What Temperature 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.

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.

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, allowing the concrete to eventually settle at 4000 psi. 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, not to mention a work hazard for employees.

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. With Powerblanket, it’s almost never too cold to pour concrete!

Temperature makes all the difference when pouring concrete. Check out our article on how temperature affects concrete that is still curing inside the Hoover Dam!

The Effects of Pouring Concrete in Cold Weather

concrete pouring temperature graphic
First, let’s define cold weather with respect to pouring concrete. Any time you have three consecutive days where the average daily temperature is less than 40°F, or if the temperature is lower than 50°F for less than half of any of the three days–that is undesirably cold for concrete. Pouring concrete in cold weather will have a detrimental affect on concrete curing for several reasons.

How Does Concrete Cure?

Concrete transforms from a liquid to a solid material through a chemical reaction. The speed of the reaction depends upon the temperature of the concrete. When the weather is warm, the reaction proceeds quickly. When it’s cold and the ground hasn’t been thawed, the reaction slows down. That’s the problem: the concrete needs to harden as rapidly as possible to resist pressures caused by water freezing within the concrete.

Slower Chemical Reactions

If the temperature is too cold, the concrete may not have reached a minimum strength of 500 psi soon enough to resist the effects of freezing temperatures. If your concrete isn’t protected with concrete curing blankets after it’s poured, it may cool too rapidly, slowing the chemical reaction.

Poor finishing techniques can also doom your slabs. Freshly poured concrete often bleeds. The water in the mix floats to the top, since it’s the lightest ingredient. Floating or troweling this water into the concrete weakens the top layer. Troweling the concrete too early can seal this bleed water just below the surface as well. If your slab is then exposed to freezing temperatures several days later, this water can freeze and fracture the top layer. Using a concrete curing blanket can eliminate the potential of freezing.

Read how Powerblanket solved concrete issues at the Statue of Liberty.

Concrete Can Be Successfully Poured in Cold Weatherpouring a concrete foundation at a jobsite

How to avoid a bad concrete pour:

  • Never pour concrete on frozen ground, snow, or ice. 
  • Be sure to order air-entrained concrete. Request a heated mix or order 100 lbs of extra cement for each cubic yard of concrete. This extra cement helps develop early strength.
  • Be sure the concrete is ordered with a low slump (drier mix). This minimizes bleed water.
  • After the final finish is completed, cover the concrete with a concrete curing blanket. The heated concrete blanket will prevent freezing and keep the concrete at an optimal curing temperature.
  • After about three days, remove heated concrete blankets to allow the concrete to air dry.

Powerblanket Concrete Curing Blankets

If you use Powerblanket Concrete Curing Blankets to pour in cold weather, your cement will cure 2.8 times faster than with conventional insulated blankets. Time and convenience are critical factors when planning out a project in the winter, and Powerblanket has you covered.  Our goal is to provide solutions to problems, and give you total temperature control over every process and aspect of your business.

We Solve Problems

From drum and barrel heaters to pipe wraps and snow melting mats, Powerblanket is dedicated to helping your business grow, saving jobs, and improving your bottom line.   Whether you need to extend the pouring season, or you are trying to survive an early winter, know that you have total temperature control with Powerblanket.

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Concrete Curing: Not Just a Wintertime Problem

If you’re in the business of concrete, then you know that winter poses the most complications when it comes to proper concrete curing. However, you’ll be equally aware of the fact that summertime also has its challenges.

 

Finishing concrete sidewalk

Summertime Concreting

Sure, winter is a far more difficult time to deal with when pouring concrete. Proper curing involves ideal temperatures, and winter imposes on these ranges more than any other season. That’s why when it comes to pouring concrete in winter, you need the assistance of a good concrete curing blanket. But what can be done to counter the challenges of summer, and what are those primary challenges?

In the summer months, you don’t have to worry about freezing temperatures. Instead, you need to watch for levels of relative humidity, temperature fluctuations between night and day hours, and an increase in the water demand for concrete curing. With these factors to consider, careful monitoring of the concrete is still an important element of the job. Hotter temperature and low humidity can increase the need for additional water, and large fluctuations between the daytime and evening temperature can pose significant problems too.

If there is the risk of a rapid drop in temperature, then there is the risk that your concrete could crack. Even though the temperature may be ideal for curing during the day, that doesn’t mean it will be at night. Certain regions can experience significant temperature variances between daytime and evening hours, and these variances should be considered potentially problematic while your concrete cures.

 

Using a Concrete Curing Blanket in the Summer?

It may seem a bit of a stretch to suggest the use of a curing blanket during the summer months, but the reality of the situation is that it can be a very reasonable call. Think about the potential scenario of dropping temperatures at night. If your concrete is curing well during the heat of the day, and then experiences a drastic drop in temperature at night, then it’s going to affect the cure and even cause potential cracking.

Using a concrete curing blanket at night would allow you to regulate the temperature range even if it’s dropping. This would produce a more uniform cure and would also speed up the process significantly. The blanket likely wouldn’t be needed during the day, but applying it at night could greatly decrease the fail rate of an expensive and time consuming project.

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.

 

Freshly finished concrete sidewalk

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 Google search 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.

Heated blankets to cure concrete

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.

Check out Powerblanket’s Concrete Curing Blankets and find one that fits your needs best.

 

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.

Download Concrete Curing Test

How Do Concrete Blankets Help Cure Concrete?

Powerblanket concrete curing blanketPlacing concrete in cold weather creates costly effects on the integrity of the concrete if precautions are not taken to provide winter protection. Both ACI 306 and the NRMCA address the need to provide a heating solution when placing concrete in “cold weather.”

Typical problems experienced in cold weather concreting include:

  1. Standard insulating blankets, regardless of “R” value, do not generate heat and have limited sustainable value when it comes to retaining the heat of hydration generated by the concrete naturally.
  2. Force air heaters and accelerators can enhance premature curing causing possible shrinkage, a condition that can result in cracking and structural damage both short-term and long-term.
  3. Freezing of the bleed water necessary during the curing process.

How would your business increase if you used heated concrete blankets?

  1. PSI ratings achieved could be achieved 2.5 times faster than conventional curing methods and accelerators.
  2. You could speed up your concrete production cycles.
  3. Because your concrete integrity and strength increased, you could move on to other jobs.

Powerblanket heated concrete blankets not only generate and evenly distribute heat but retain that heat over longer periods of time allowing the concrete to avoid detrimental freeze-thaw effects during early stages of the curing process, an event that can greatly reduce the integrity of the concrete by as much as +/–  40 percent.

Check out Powerblanket’s Concrete Curing Blankets and find one that fits your needs best.

Pouring Concrete on Frozen Ground

 heated blanket versus open flame to thaw groundWhen temperatures are cold, it’s tough to schedule your jobs because you can’t control the weather. You can lose time and money, and it’s extremely hard to schedule your sub-contractors. If you wait for the weather to break, you might find yourself waiting a long time. Powerblanket® concrete curing blankets eliminate the weather variable and keeps your downtime to a minimum.

Unlike normal insulated blankets, Powerblanket Multi-Duty curing and thawing blankets allow you to unthaw frozen ground prior to pouring. Simply place them ahead of time and when your crew is onsite the ground will be ready for pouring – and on your schedule, not the weather’s.

Once you’ve poured, the same blankets will allow you to maintain the optimal curing temperature, ensuring a strong, durable slab, within a predictable time-frame that keeps your job moving.

For rapid thawing, use Powerblanket Extra-Hot Thawing blankets, which provide a number of advantages over other ground-thawing methods:

  • No open flames
  • Faster & more economical
  • No carbon monoxide discharge
  • No noxious fumes
  • Safe, energy-efficient, and environmentally friendly

electric blanket thawing ground with snow on itPowerblanket frozen ground thawing and concrete curing blankets allow concrete work to continue through the winter: you can efficiently schedule your crews and equipment and maintain a steady work schedule throughout the year.  

A final tip: NEVER POUR FRESH CONCRETE ON FROZEN GROUND. You now have a solution for thawing frozen ground and curing concrete in any weather condition. Keep your jobs and your crews on schedule with Powerblanket.

 

To learn more about the cure for common cold concrete, click here.

 

 

General Guidelines for Durable Concrete in Cold Climates

Cracked concrete wallHere are some guidelines to follow for trouble-free concrete in cold climates:

Maintain a Low Water to Cement Ratio

The cement in concrete is the glue that holds everything together. The more water you add when you mix, the weaker the concrete will be for a given amount of cement. While adding water to concrete makes it easier to pour, it can also weaken the concrete.

Use no more than a Four Inch Slump

Slump refers to the stiffness of the mix. The lower the number the stiffer concrete is. Concrete can actually be mixed and poured with a one or two inch slump. Highway median crash barriers are frequently poured with a 1 or 2 inch slump. The resulting concrete is stiff enough to stand three to four feet tall within moments after pouring. It also becomes extremely strong once it’s cured. Have you seen highway median work where the crash barrier is done with a forming machine? The concrete is so stiff that it can stand four feet tall moments after it is poured – yet it attains a high strength once cured and dried.

Use a Six Bag or 4,000 PSI Mix

You must have enough cement in each cubic yard to make sure it is strong. For concrete exposed to freezing temperatures you’ll need a minimum of 6 bags (564 lbs) of cement per cubic yard, or mixture strength of 4,000 pounds per square inch.  Diluting your mix will often result in weak and damaged concrete.

Use Air-Entrained Concrete

Special chemicals can be added to concrete as it is mixed. These chemicals create micro-air bubbles within concrete. The air spaces become shock absorbers as water freezes within concrete. Make sure you use air-entrained concrete in cold temperatures.

Create the Right Slope

Concrete slabs need to have good drainage. Slabs need a minimum slope of 1/4″ per linear foot to shed water. If water pools on the surface and freezes, the concrete can be damaged.

Provide Adequate Curing Conditions

If the temperature is too cold, the concrete may not have reached a minimum strength of 500 psi soon enough to resist the effects of freezing temperatures. If your concrete isn’t protected with Powerblanket™ concrete curing blankets after it’s poured, it may cool too rapidly, slowing the chemical reaction. Use concrete Powerblanket™ concrete curing blankets to maintain the optimal curing temperature of between 65 – 85°F.

Don’t Use Silicone Sealers

If you feel the need to seal your concrete, don’t use silicone sealers. Silicon sealers form a film. Use a breathable sealant or water repellent containing silanes or siloxanes.

Heat curing concrete methods

Use a Heated Powerblanket

Powerblanket heated thawing and concrete curing blankets effectively remove frost from work sites and allow concrete to cure at optimal temperatures without risk of freezing or rapid drying.

For more about concrete curing solutions, click here.

Placing Concrete in Cold Weather – An Overview

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Placing Concrete in Cold Weather - An OverviewThe performance of many building and remodeling materials is deeply rooted in basic chemistry and physics. Concrete seems like a simple product… but in reality it’s a highly sophisticated chemical compound. Due to its sophistication, care must be taken in its application to ensure proper curing and strength.

Hard, gray Jell-O

In some ways concrete is like Jell-O. You take a powdered mixture, mix it with water, stir it up, and before long you have a semi-solid compound.

There is a difference, however, between concrete and Jell-O. The cold temperatures in your refrigerator speed up the transition of the liquid mixture into a semi-solid material. With concrete, cold temperatures slow this transition. In the case of concrete, cold temperatures can be disastrous.

Crystals in Concrete

Concrete is a strong material because of its chemistry. When you mix water with the cement powder, you start an irreversible chemical reaction. Tiny crystals begin to grow. These crystals attach to one another, the sand and the gravel in the mixture. When everything goes right, you’ve created a compound hard as rock.

When water freezes it also turns into ice crystals. This transition would normally be no problem, but as the ice forms the volume of the water grows by nine percent. (That’s why ice cubes end up larger than the volume of water that produced them.) The ice tends to push or break things that get in its way.

In the case of freshly poured concrete, ice can destroy your slab. Enough cement crystals must be allowed to grow within the concrete to withstand the forces of growing ice crystals. Depending on the outside temperature, it can be a race against time. Most concrete chemists and engineers agree that if the concrete can attain a minimum strength of 500 pounds per square inch (PSI), it can resist ice damage.

Hot Stuff

The chemical reaction of concrete formation creates heat. This heat can be trapped by the use of insulating blankets. But if it’s cold enough, insulating blankets won’t keep the temperature at an optimum level for maximum curing efficiency. No insulating blanket will keep concrete at a temperature between 65 – 85°F, the optimum temperature range for proper concrete curing.

To ensure the concrete maintains the optimum temperature range, use Powerblanket® concrete curing blankets. Powerblanket® concrete curing blankets are heated blankets that not only insulate the concrete, holding in heat it naturally produces as it forms, but they also produce additional heat to keep the concrete within the desired temperature range.

Temperature is one of the most influential factors in determining the strength of concrete. For more information on that subject, click here.