Concrete Curing in Freezers

An Atypical Concrete Job

Concrete curing in freezers is a unique experience. Walk in freezer concrete floor construction requires a specially cured solution that can handle constant sub-freezing temperatures. This concrete is also required to be strong enough to support heavy equipment traffic from forklifts and other machinery. These freezers are a crucial part of the cold chain that protects the safety of cold products (such as meat, ice cream, medicine, cadavers, liquid oxygen, and more) during transport and storage. Walk in freezer failure is an expensive, and dangerous broken link in that refrigeration cold chain. When the structural integrity of a walk in freezer is jeopardized, the contents within can spoil, creating a huge employee and consumer safety hazard. Not all walk in freezer failures are preventable. However taking a few extra precautions during concrete curing in freezers can prevent costly downtime and repairs.

concrete curing in freezers
Image taken from www.garonproducts.com

Prepare The Ground

There are a number of layers that need to be in place before pouring to protect your concrete from freezer floor heave. Freezer floor heave occurs when the moisture in the soil freezes and expands below your slab. If the soil then begins to thaw, it will also sink and settle, causing massive damage to the concrete above. Protective layers of insulation, vapor barriers, mud-slabs, and sub-slab glycol heating prevent the soil from freezing and swelling below your concrete floor.

Maintain The Mix

Ensure your mix of concrete doesn’t contain too much water. An overly wet mix is likely to cause cracking due to shrinkage. The water can also freeze within the concrete if it’s not cured enough by the time the freezer begins operating. Your concrete freezer floor may appear set on the surface, but the lower layers will not be strong enough to bear weight or thermal stress. 

Ensure The Cure

Walk in freezer floors need to endure constant walking foot traffic, heavy stacks of pallets, and forklifts. Your concrete needs all the compressive strength it can get to withstand such thermal and physical stress. Using concrete heating blankets, instead of traditional insulated blankets, ensures your concrete floor cures faster and to a stronger PSI rating.

Seal The Deal

The United States Dairy Association (USDA) has a zero-tolerance policy regarding leaks within a freezer. Frozen food requires storage at 0°F, as “freezing to 0° F inactivates any microbes — bacteria, yeasts and molds — present in food.” Leaks allow moisture to invade the freezer, which can trigger mold and other harmful pathogen growth. Properly sealing concrete floors in a walk in freezer protects your slab, prevents leaks, and maintains USDA safety compliance requirements. 

Restoring Concrete Freezer Floors

Concrete floor damage, like cracking or chipping, is triggered by a number of factors such as: forklift accidents, threshold damage, sub-floor heating replacements, and freezer floor heave. Our friends at Concrete Mender warn of several concrete repairing challenges:

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.

Ambient Temperatures

Mixing epoxies or mortars in the cold is especially challenging. As the temperature decreases, the viscosity of these materials increase making them very difficult to pour, mix and work with. Bucket and drum heaters are an excellent solution to keeping epoxy and mortar warm while waiting to use on a freezer floor.

Powerblanket diagram showing the affect of temperature on fluid viscosity

Curing

Materials used to patch and repair concrete cure much more slowly at cold temperatures. A product that takes 1 hour to cure at room temperatures can take 12 hours to cure in cold temperatures. Some materials may actually freeze solid before they can cure properly. Keeping patching materials warm during the curing process will cut down your cure time and increase their durability. Curing blankets are the most efficient way to ensure your repairs cure quickly and firmly. Curing blankets heat through conduction and have complete surface contact to transfer heat directly where it is needed most.

Concrete Solutions From Powerblanket

There are a lot of elements involved in preparing and pouring a concrete freezer floor. When things go wrong, repairing a damaged freezer floor is just as challenging. Taking extra precautions before, during, and after you pour will ensure your slab is built to last.

For everything about concrete curing in freezers, Powerblanket is here to help. With our wide range of bucket and drum heaters, you can keep your materials warm and ready to use for any repair job. Our concrete curing blankets are the perfect solution for quickly achieving high PSI ratings. With a cure rate 2.8 times faster than conventional insulated blankets, you can be sure to meet project deadlines on time. Contact us to find the perfect solution for all of your concrete needs 855.447.9358 or [email protected] 

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Concrete Curing Blankets

Cold Weather Concreting

Imagine arriving at the job to find a fresh layer of ice and snow on your pour site. The weather forecast shows continual sub-freezing temperatures, and you are worried about getting the concrete stage done so your crew can keep the project on schedule. Even if you manage to successfully pour your slab, what will the end result be? It will take forever to cure, or not finish curing at all. The result may be a fragile, partially cured piece of concrete, riddled with defects from thermal stress.

It’s no secret that curing concrete in cold weather is a tricky endeavor. Mother nature can catch even the best trained crew off guard during the winter, and cause costly construction delays.

Conventional Concrete Warming Products

To avoid completely shutting down work during the winter, some construction crews turn to conventional concrete warming products and practices.

Insulation

Concrete hydration is an exothermic process and does create some heat. This heat can be trapped (to some degree) with the use of insulating blankets or straw. However, when pouring concrete in cold weather, providing thermal insulation is only half the battle. Insulation alone does not create heat and will not provide enough surface contact to effectively trap heat on really cold days.

Forced Air Heaters

Some crews build temporary enclosures over their pour site and use heaters to force hot air over the slab. This radiant heating method spends more time and energy heating the air around the concrete instead of heating the concrete itself. During the winter, a lot of heat can also be lost through the bottom layer of the slab into the sub-grade. This uneven heat will cause the top layer of concrete to cure much faster than the bottom, leading to shrinkage and a weak cure.

Calcium Chloride

Using accelerators, like calcium chloride, in your concrete mix is a two edged sword. It can certainly reduce winter cure times, but it also contributes to a variety of defects. Calcium chloride can cause corrosion of steel reinforcements in your concrete. It can also increase volume shrinkage, scaling, efflorescence, and discoloration.

Electric Concrete Curing Blankets

When you combine heating power with the protection of insulation, a world of possibilities opens on your job site. Not all blankets are created equal, and Powerblanket’s concrete blankets are a cut above the rest. We specialize in total temperature control that gets you and your crew back to work.

How Powerblanket Products Work

Heat Transfer Through Conduction

Powerblanket saves you time, energy, and money by putting the heat precisely where it is needed. By simply placing down our concrete curing blankets, you are harnessing the power of conduction and heating your concrete directly. Fresh concrete must stay above 50°F for 48 hours in order to hydrate and cure to a strong finish. Direct conductive heat gives you peace of mind and takes the hassle out of curing temperature maintenance.

concrete curing blankets

More Surface Area Contact

During wet, windy, and cold winter conditions, surface contact between your heat source and your concrete is critical. Our concrete curing blankets have 10x more surface contact than other blankets. More surface contact means even and controlled heating so your concrete cures uniformly.

Weather Proof Insulation

concrete curing blankets

Simply put, thermal insulation reduces the transfer of heat between objects. Our heavy duty, weather-proof insulation provides a protective barrier from the elements and reduces heat loss. Our insulation doesn’t just trap the exothermic heat generated by the hydration process. We combine insulation with efficient heating elements to direct heat downward right into your concrete slab instead of losing it to the winter air.

Powerblanket Benefits

 

concrete curing blankets

Faster Cure

Winter conditions notoriously slow down or sometimes stop concrete from curing. Our concrete curing blankets cure 2.8x faster than conventional insulated blankets. Faster cure times allow your crew to move on to the next building stage and help your project finish on schedule.

Maintain Moisture During Hydrating Process

Moisture loss during hydration weakens the cure of your concrete. Our blankets protect your slab from the elements during the hydration process and allow the necessary chemical reactions to finish.

Easy to Install and Remove

Forget bulky heaters, finicky straw, and time consuming enclosures. Simply place our concrete blankets down and let them do the work for you. They are easy to remove and store for future needs so they can continue to save you time and money down the road.

Stronger Cure

Powerblanket ensures your concrete is durable and built to last. By using our concrete curing blankets you can produce a 3,925 psi rating in just 72 hours.

Prevent a Freeze Cycle

Freezing during the early stages of curing can greatly reduce the integrity of the concrete by as much as 40%. 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 damaging freeze-thaw cycles during curing.

Reduce Downtime and Increase Profits

Fewer tasks hold up a construction site like concrete troubles. Save yourself from expensive repairs and re-pours by having the right temperature control products on hand before disaster strikes. Curing your concrete quickly and strongly allows your crew to meet deadlines and move onto the next building stage.

Thaw Ground and Warm Sub-grade

Our concrete blankets can serve multiple purposes on your site. By placing them down before a pour, you can thaw frozen ground and heat your sub-grade. This not only protects your concrete from losing heat into the ground it also reduces thermal cracking that occurs when warm concrete is poured directly onto a frigid surface.

ACI Certified

We are dedicated to providing high quality and reliable concrete solutions and all of our concrete blankets are cold weather certified by the American Concrete Institute.

Powerblanket Guarantee

With total temperature control from Powerblanket, there is no off season. We keep your crew working and your job site productive all winter long. Contact us to find the right concrete solution for your needs at 866.945.4203 or [email protected]

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Curing Cold Concrete: Electric vs. Insulated Blankets

Electric concrete blankets versus insulated blankets. Which one is best and why is it Powerblanket?

Not All Concrete Insulated Blankets Are Created Equal

If you happen to read almost any do-it-yourself guide, you will likely see a sentence that says, “If temperatures are below 40°F, use insulated blankets or straw to keep your freshly-poured concrete from freezing.” Well, that sounds nice and easy, but simply keeping concrete from freezing isn’t enough.

Why Heat Concrete?

The optimum range for proper concrete curing is between 65° – 85° F. When concrete dips below that range, ice crystals can form, cure strength will be compromised, and several temperature based defects can occur. Concrete pouring is a critical stage in any construction project and problems derail progress when it needs to be repaired or re-poured. Solely insulating concrete during curing seems appealing and money-saving, but can lead to costly time delays and expensive re-works.

What is Thermal Insulation?

Simply put, thermal insulation reduces the transfer of heat between objects. There are a myriad of both natural and synthetic materials used to insulate objects in different industries. When thermal insulation is placed on something that is already warm, it will prevent heat from escaping.

The chemical reaction of concrete formation is exothermic and does create some heat. This heat can be trapped (to some degree) with the use of insulating blankets or straw. But if it’s cold enough outside, insulating blankets won’t keep the temperature at an ideal level for maximum curing.

Insulation + Heating

When pouring concrete in cold weather, providing thermal insulation is only half the battle. Most insulated blankets will not provide enough surface contact to effectively insulate your concrete on really cold days. Combining the protective power of insulation plus even heat distribution gives you an advantage over mother nature.

Electric concrete heating blankets provide the protective layer of insulation and an extra boost of heating power to keep your concrete between 65° and 85° F. Concrete blankets have 10x more surface contact than other blankets. They efficiently transfer heat down into your concrete while heavy-duty weather-proof insulation protects it from the elements and heat-loss.

Thaw Before Your Pour

No insulating blanket on its own will thaw frozen ground, and pouring concrete on frozen ground can have serious repercussions.

electric ground thawing blankets

Electric ground thawing blankets are the best way to ensure your concrete pour gets off on the right foot. Using an electric ground thawing blanket prepares the ground before you pour so ambient temperatures above and below your concrete are at ideal levels.

Concrete Curing BlanketsMany factors have an effect on concrete cure time, such as the type of mix used, the size and shape of the slab, and the ambient weather. Of all these factors, weather and temperature is the most unpredictable. The colder the temperature, the longer concrete will take to set and reach its proper strength. During cold weather, a conventional insulated blanket will cause the concrete to take longer to cure and will result in a weaker concrete.

For example, concrete kept at 70°F will set in approximately 6 hours, whereas concrete kept at 40°F will take 14 hours to set. Concrete maintained at 70° F will reach a compression strength of 2,700 psi in 3 days; concrete maintained at 40° F will only reach a strength of 1,200 psi in 3 days.

This disparity in strengths makes a huge difference in whether your construction project can proceed. If concrete takes too long to set, cure, and strengthen, your project can be significantly delayed. Some concrete manufacturers find it too problematic to operate during the winter, creating a costly off season.

Concrete Solutions From Powerblanket

With Powerblanket, there is no off season. The difference between conventional insulating concrete blankets and electric concrete curing blankets is clear, and our electric blankets are a cut above the rest. By combining heavy weatherproof insulation with electric heating components, Powerblanket can cure concrete 2.8 x faster than conventional insulated blankets.

Our ground thawing blankets melt ice and snow and prepare the ground before your concrete is even poured. Our concrete curing blankets then maintain the temperatures you need to more quickly cure your slab to a strong finish. Powerblanket can eliminate costly weather delays, ensure your project proceeds on schedule and that your concrete will be long-lasting and durable. Contact us to find the right concrete solution for your needs 855.440.0208 or [email protected]

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