How to Keep Mortar from Drying Too Fast

You are working on your mortar mix for your brick and stone wall refurbishing. Now, you wonder how to keep it from drying and curing too fast. Don't fret! We’ve done the research to give you the correct information for your DIY project.

A straightforward way to keep the mortar from setting off fast is to add cold water to the mixture. When this technique fails, consider mixing the mortar in smaller batches at one time which is enough to cover a workable area.

The correct application of mortar is crucial for the success of your masonry project. Remember that the product has its limitations, too. In this post, we will discuss the nature of the mortar mixture, ways to slow its drying, and other problems that may arise. Differences between grout mortar and thin-set additives are also explained in detail. Without further ado, let's get into it.

Plasterer concrete worker at wall of house construction, How to Keep Mortar from Drying Too Fast

Mortar: An Overview

Mortar is a type of building material composed of cement and fine sand. Lime is added for improved durability. Cement is the binding element. To work with mortar, water is added to activate the cement. Then it takes into a paste form, hardens, and cures.

Brick plastering with a worker hand aligning the bricks

Mortar is the bonding agent to hold together bricks, blocks, natural stone, veneer stone, and other masonry construction. It is used for the layering of bricks and stone. It is also applied to fill in the gaps and joints of bricks and blocks.

There are two kinds of mortar, grout and thin-set, which are discussed further in the succeeding section.

Interested in learning more about mortar? We have these posts for you:

What Type Of Mortar To Use For Plastering

What Type Of Mortar To Use For Brickwork

The Rationale Behind Adding Cold Water

While working, if you have noticed that the mortar is hardening faster than you would expect, adding cold water to the mixture proves to be a go-to remedy. 

Now, you might wonder why cold water can solve the problem. How does it work on the drying mortar?

The hot and warm climate accelerates the hardening of mortar. The dry air in the atmosphere can cause rapid moisture loss in the mixture. This weakens the bonding elements and causes it to lose its function. 

In fact, manufacturers have introduced a "hot weather" variant of mortar. Certain chemicals are added to this variant to retard the curing of mortar.

If you happen to work indoors, it is recommended that you power on the air conditioning unit if there is one available. The cool air that circulates the room can extend the pot life and open time of the mortar.

If you are working outdoors, you need to provide shading in your work area to protect yourself and the working area from the high temperature and heat of the sun. More importantly, you are not exposing the mortar to the intense heat.

In order not to be caught in the dilemma of mortar drying too fast, the most logical workflow is to mix in small batches. You should familiarize yourself with the area you would be working on to be covered by the smaller volume of mortar mix you have made. 

Construction worker put cement on a bucket

Working in smaller batches of mortar mix may be inconvenient and time consuming with added labor costs, but the beneficial outcomes are significant. There would be less material waste, less probability of incorrect mixing ratios, and quality workmanship.

What Is The Pot Life Of Mortar?

Pot life is the amount of time that you can work on the mortar mix in your bucket. Open time is how long the mortar can be worked on as you install your tiles or bricks.

Once the mortar is mixed, it can be worked on for approximately 90 to 120 minutes. Avoid mixing more than you can apply in the allotted time since the excess mortar will become too dry and useless.

Can Water Be Added To Dry Mortar?

During application, ensure to complete the dry ingredients first before adding water. As mentioned earlier, you can add water; cold is better when the mortar starts drying.

The only thing to remember is to not add water if the mortar has already hardened. You can consider adding masonry cement to improve the workability of your mixture.

Masonry cement has a special formulation to be used for mortar. It contains plasticizers such as limestone, so it has stronger bonding properties that could reinforce the already hardened mortar. This results in improved workability of the mortar mix. 

Shop for this masonry cement on Amazon.

What Happens If Mortar Dries Fast?

Builder hands with a metal spatula kneads in a large

When mortar dries quickly, contraction among its elements occurs. The drying process hydrates, and lime carbonation gets inhibited. This means that there is restricted movement of CO2, or carbon dioxide, within the mixture. 

If you proceed to apply the drying mortar, you will notice a crumbled or powdery texture on the surface of brick joints. There is a chalky or pulverized finish. This is an indicator of a failing mortar. Its bonding strength is significantly reduced.

This is a sign of poor workmanship that compromises the quality and durability of your masonry setting. Your stone finish might not last as long.

Mortar drying too fast significantly reduces the speed of carbonation, thus leaving the product vulnerable to frost.

Why Does Mortar Keeps Cracking?

There are instances that you would notice the mortar cracks just right after you have finished brick layering. This happens because the dry bricks just laid down absorb or soak up the moisture from the mortar too fast. 

To prevent this immediate mortar cracking, it is recommended to wet or soak the bricks for more than an hour before layering them. In this way, the moisture absorbed can prevent the bricks from absorbing from the mortar, thus further improving a stronger and better bonding.

Other Factors That Induce Curing Of Mortar

To maximize the usefulness of working with mortar, there are other factors that accelerate drying time. It is not recommended to add chemicals to the mix just to avoid drying faster. This could compromise its quality and compression strength.

Here are a few factors that make mortar dry fast:

  • Wind can induce fast drying. You must provide physical barriers as a quick remedy. Ensure that nothing is blowing in the area you are working on. Yes, it can be open and ventilated, but there should be no forced air blowing.
  • The surface you are working on could be too hot. For example, the exterior wall you must adhere to is exposed to UV heat. Let it cool down first before working on it.
  • Since mixing is done manually, there is a probability of incorrect mixing ratios. There may be insufficient cement, which can negatively affect the mechanical attributes of the mortar. Fast drying is one element resulting from incorrect mixing.

The key to managing the curing of mortars is to protect them from heat, rain, and wind. As with any other product, it also has its limitations.

How Long Does Mortar Take To Be Fully Dry?

It takes 24 hours to cure 60% of the mortar's compressive strength. It will take another 28 days to reach its full cure strength. These numbers may not be universal since environmental variables affect curing time. 

Additionally, mortar should be kept wet or moist for approximately 36 hours to be fully cured. The weather and other environmental factors pose a challenge to achieving this. The weather may become too hot or too cold. Both extreme temperatures can negatively affect the full curing of mortar.

Heavy rain after brick layering can wash away the lime content of mortar, thus weakening its bonding strength between brick and mortar. The serious and laborious consequence will be redoing the job.

In hot and temperate climates, the moisture of mortar will be quickly absorbed, causing it to dry and shrink. It eventually sucks the moisture from the newly layered bricks. The obvious consequence of this would be the bricks beginning to crumble. This will hamper the structural strength of the masonry setting.

What Are Grout And Thin-Set Mortars?

Grout is a type of mortar but without the lime component. It has high water content; thus, it flows to fill gaps between tiles after installation. Due to this, grout is not used for binding but mainly to fill the spaces in-between to prevent water seepage, chips, and cracks at the tiles' edges.

Grout mixtures are commercially available. For the user's convenience, they are pre-mixed and ready to apply. Nowadays, there are also variants that have various color pigments to choose from. Grout color adds to the overall appeal of the tiled surface.

Shop for this grout mix on Amazon.

Construction tools for concrete job

Thin-set is another form of mortar. It has the same components, and water retention compounds are added. Due to this, it is perfect for bonding tiles to plywood, cement board, concrete, and other substrates. Some types have added latex and polymer to increase the bonding strength.

Due to the significant adhesive element, it is called the thin-set adhesive. You can buy it in dry and pre-mixed forms. Pre-mixed are expensive, but it gives added convenience and consistent mixture ratios.

Shop for this thin-set mortar on Amazon.

You may be interested to learn more about grout and tiling; we have this post for you:

What Type Of Mortar To Use For Tile?

Final Thoughts

Plasterer concrete worker at wall of house construction

Don't worry when your mortar dries faster than you expected. Adding cold water is a quick remedy. It is important to maintain moisture in your mortar mixture to not compromise the quality and long-term durability of your masonry project.

The bottom line is to control the curing of mortar by protecting it from heat, wind, and rain. Work in small batches that you can manage to apply within its pot life in a workable area before it hardens and loses its strength.

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