How Long Does Mortar Take To Cure?

January 13, 2020

How Long Does Mortar Take To Cure?

As construction projects progress, it can be exciting to reach the final stages. Applying finishing touches to newly reconstructed or refurbished surfaces results in eye catching aesthetics. Mortaring tiles or other masonry, adds a final polish to all your hard work. Just like concrete, mortar requires careful planning and execution to make sure you achieve the ideal cure strength and a strong finish. Let’s take a closer look at what affects mortar cure time and the strengths of different mortars.

WHAT IS MORTAR?

Mortar…Grout, What’s the Difference?

Mortar

Mortar is a mixture of sand, water, lime, and cement. It is used to bond heavy materials together (like bricks and stones) and provide structural integrity. It can also be used for thinner materials (like tiles) to create a bond between the tile and the substrate. Mortar has a lower water content than grout and should only be made with enough water to make it smooth and buttery in consistency.

Grout

Grout is a pour-able paste that is used to fill crevices or gaps between tiles that is used after the mortar has become set. It has a higher water content than mortar, which makes it easier to spread. Due to its thinner consistency, grout is not an adequate substitute for mortar.

TYPES OF MORTAR

There are many different types of mortar and each are ideally suited for different applications. Each type cures to a different compressive strength and should be carefully selected to make sure your mortar matches the cure strength you need.

Thinset

Thinset mortar is also known as dry set or dry bond mortar, It contains a water retaining additive that assists with the curing and hydration process. It is most frequently used for tiles and counter-tops. Thinset mortar takes between 24-48 hours to cure. Thinset comes in a variety of mixes that are usable for a wide range of tiles and materials. Each type of tile has different cure strength requirements so make sure to select the right mortar mix for your tile selection.

Brick Mortar

Brick mortar is made from Portland cement and is used for more structural and load bearing projects. It will reach 60% of its strength within the first 24 hours and will take up to 28 days to reach its full cure strength. There are 5 types of brick mortar, and all cure differently than each other.

Type M

Type M mortar cures to a minimum strength of 2500 psi and is the strongest type of mortar. It is used for projects that need to withstand extreme gravitational forces and hold large lateral loads.

Type S

Type S mortar is a medium strength mortar that cures to a minimum compressive strength of 1800 psi. It is typically used on exterior walls, patios, paving, and other projects where mortar comes in direct contact with the ground.

Type N

Type N mortar is common, general purpose mortar that cures to a minimum strength of 750 psi. This type of mortar is commonly used for general masonry projects and to reinforce interior walls.

Type O

Type O is a low strength mortar that only cures to a minimum compressive strength of 350 psi. It is only safe to use on non-load-bearing interiors, superficial (non-structural) repairs, or on soft masonry like sandstone or brownstone.

Type K

Type K is the lowest strength mortar available and has a very limited purpose. It only cures to a minimum strength of 75 psi so it is primarily used for historical preservation. It is not used for anything structural or load bearing due to its low cure strength.

MORTAR CURE TIME

Mortar typically will cure to 60% of its final compressive strength within the first 24 hours. It will then take about 28 days to reach its final cure strength. However the curing process does not always follow a universal timeline. There are a few key environmental variables that affect your mortar cure time. Ambient temperature, air flow, the amount of water used in your mix, and humidity all affect mortar curing time.

Temperature

According to top concrete manufacturer TCC Materials, “normal temperatures are those between 40°F-100°F (4.4°C-37.8°C). Cold weather then occurs when ambient temperatures drop below 40°F (4.4°C).” When you work within the normal temperature range, you can expect your mortar to follow the typical cure timeline.

“Cold weather can slow construction by affecting the set time and strength development of mortar and grout. If weather gets below 40°F (4.4°C) within 24 hours for mortar and 24-48 hours for grout hydration of cement will stop until temperatures become warm enough for hydration to continue.”

Waiting for warm weather is not always ideal or even possible when you are adhering to a construction schedule. Using curing blankets to protect your mortar during the curing process can keep you on track and help your mortar cure to full strength.

Air Flow

The chemical process of curing depends upon the mix staying hydrated. High winds and fans will strip your mortar of the moisture it needs to stay hydrated and cure properly. For interior mortar work, consider turning off fans that can impede the curing process. For exterior work, you will need to make sure you protect your mortar from high winds and possibly add more moisture as it cures to reduce cracking. Most mortar manufacturers will provide re-hydrating instructions for their particular products.

Water

Be sure to carefully follow your mortar manufacturer’s guidelines for mixing ratios. Your mixture should only contain moisture in specified amounts. Too much or too little water will not only change your mortar cure time and cure strength, it will also make it difficult to work with.

Humidity

Maintaining proper moisture levels is critical for your cure time and final cure strength. That means that even the moisture in the air itself needs monitoring. If you are building under extremely low humidity, you may need to add more moisture your mortar to assist in the curing process. Working in high humidity can possibly increase your mortar cure time, but will require less moisture maintenance on your part.

Setting vs. Curing

Even though mortar will not be completely cured, before long it will become set enough for you to move onto the next steps. After 24-48 hours, depending upon the humidity and ambient temperature, you can begin applying grout.

POWERBLANKET MORTAR SOLUTIONS

Concrete Curing Blankets

Few have the luxury of restricting temperature sensitive work to warm weather days. Thanks to Powerblanket, there is no costly off-season and mortar work can continue all year long. Our concrete curing blankets can cure 2.8 x faster than conventional insulated blankets. We can safely insulate your mortar and protect it from losing heat and humidity during the curing process. Contact us today at 855.447.9358 or [email protected] to find the perfect curing solutions for your mortar needs.

Learn More About Curing Blankets

Concrete Curing Blankets

by Justin Hawkes

March 4, 2018

Concrete Blankets Concrete Insulation Blankets Construction Industry Curing Concrete in Cold Weather Freeze Protection Industrial Heating Blankets Winter Preparation

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.

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

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

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]

Learn More About Concrete Curing Blankets

Curing Cold Concrete: Electric vs. Insulated Blankets

by Jeff Cheney

September 15, 2019

Uncategorized

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 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.

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