Types of Mortar Mix – Uses and Tips for Mixing

Few types of mortar mix

Mortar is a mixture of Portland cement, hydrated lime, and sand combined in precise amounts to fulfill specified requirements.

It acts as a binding agent that helps to hold bricks or other masonry units together while providing additional strength and stability to the overall wall or structure.

Typically, the four main types of mortar are categorized as follows: N, O, S, and M.

All of these use a combination of cement, lime, and sand; however, the ratio in which these ingredients are mixed together produces different results and variations in properties like flexibility or compressive strength.

The best type to use depends on the project requirements set forth by the mason.

So, further, in this article, I will explain the differences between each type of mortar along with the standard mortar ingredients ratios for a yield of 1 cubic yard, usually given in a volume of cubic feet (cu ft).

Hopefully, the information here will help you select the best one for your project while prepping the brick walls or other masonry surfaces before painting.

N Type Mortar Mix

Type N mortar mix is the most common type of mortar and is made with 1 part Portland cement, 1 part hydrated lime, and 6 parts sand.

This mortar mix comes with medium compressive strength and is among the best choices when it comes to general applications.

Primarily, the Type N mortar is a general-purpose mix recommended and used for:

  • Soft stone masonry (such as limestone)
  • Above grade, exterior, and interior load-bearing installations
  • Stone veneers are exposed to severe weather conditions like high heat and moisture

Type N mortar typically reaches 28-day strength at around 750 psi compressive strength.

To protect your work, it is best to apply a waterproofing membrane once you have finished the project.

Type N Mortar Mixing Ratio

  • Sand 20.25: cu ft
  • Hydrated lime: 3.375 cu ft
  • Portland cement: 3.375 cu ft

O Type Mortar Mix

Type O mortar mix is not as strong as other types, with a compressive strength of only 350 psi (pounds per square inch).

Because of its weak structural capacity and strength, the Type O mortar mix is not an ideal candidate for exterior use, especially the locations where high winds exist.

Therefore, it is most often used for walls indoors, and above-ground that won’t be carrying heavy weight (non-load–bearing).

While Type N can also be used indoors in some circumstances, Type O is better suited for repair work, such as repointing older structures, because it’s easier to apply evenly.

Type O Mixing Ratio

  • Sand: 20.25 cu ft
  • Hydrated lime: 4.5 cu ft
  • Portland cement: 2.25 cu ft

S Type Mortar Mix

Type S mortar is incredibly strong, with a compressive strength of over 1,800 psi and high-tensile bond strength.

Although this mortar mix must have a minimum compressive strength of 1,800 psi, it’s often mixed to achieve strengths between 2,300 and 3,000 psi.

Type S mortar is an ideal choice for many projects at or below grade that need to withstand soil pressure, wind, and seismic loads.

Primarily it’s found useful for below-grade applications like masonry foundations, manholes, retaining walls, and sewers.

But it can also be used for at-grade projects like brick patios, driveways, and walkways.

Remember that if you are working with a glass block, you will need a special mortar that is white glass block mortar.

Even though it would be classified as a type S mortar, it has been formulated to exceed the requirements for strength set by type S mortars.

Type S Mixing Ratio

  • Sand: 20.25 cu ft
  • Hydrated lime: 2.25 cu ft
  • Portland cement: 4.5 cu ft

M Type Mortar Mix

Type M mortar, which contains the highest amount of Portland cement, is best for hefty loads and applications beneath the ground, such as foundations, retaining walls, and driveways.

While type M mortar helps achieve at least 2,500 psi of compressive strength, it has poor adhesion and sealing qualities compared to others. 

This makes it unsuitable for certain outdoor applications where external elements can be a problem.

Since type M has a similar strength to natural stone, it is ideal for use with natural stone.

That said, you will need to use a special high heat mortar, also known as refractory mortar, which is formulated to handle temperatures exceeding 500 degrees Fahrenheit – in case you are working on projects like fireplaces, chimneys, or fire pits in your backyard.

Type M Mixing Ratio

  • Sand: 20.25 cu ft
  • Hydrated lime: 1.6875 cu ft
  • Portland cement: 5.0625 cu ft

Type K Mortar Mix

Type K mortar has a very low compressive strength of around 75 psi and is not commonly used for new construction.

But it can be specified for certain applications, like restoration or special projects that require a bit of extra strength.

Because it is soft, type K is mainly used to restore the masonry on ancient historical buildings that require a mix that isn’t much stronger than the existing masonry.

What is Thinset Mortar?

Many times the word “thinset” is used interchangeably with “mortar.”

Thinset, unlike mortar, is a paste composed of water, cement, and sand that is thinner and intended particularly for tiles.

Thinset also may contain additives for increased bonding, water resistance, and flexibility.

Bricks stacked on top of each other are considerably more durable when compared to brick walls built with conventional mortar.

On a similar note, Thinset also contains cement, but its formulation isn’t strong enough to support structures or even act as a stand-alone flooring product.

The standard mortar mixing ratio for thinset is one part mix to four parts water which is generally mixed for about five minutes to get the right consistency.

way to mix mortar

How to Mix Mortar Correct Way?

Mortar mix is a crucial building component that must be properly mixed.

It is usually prepared on-site in a mechanical mixer, but it can also be prepared in smaller amounts by hand using a hoe and mixing tub or wheelbarrow.

When mixing mortar, first and foremost, always utilize eye protection and waterproof gloves.

Plus, to guarantee that no unexpected or unwanted materials enter the mix, you should always use clean tools.

Once you are ready with the safety gears and supplies, here is a step-by-step procedure for mixing mortar the correct way:

  1. Start by measuring the materials using a clean, dry bucket
  2. Wet your mortar container slightly with some water before adding fresh mortar.
  3. If mixing by hand, choose a container that has a flat base and tall sides.
  4. Mix the lime, masonry cement, and sand in your mixing container to the appropriate proportions, then top with water.
  5. To mix by hand, fold the mortar mix from the bottom up into the water. Continue mixing until all of the water is incorporated.
  6. Then add more water and continue mixing. Continue adding water until the mortar reaches a smooth texture.
  7. You’ll know the mortar is wet enough to stop mixing when it falls off the shovel easily but it still holds its shape if you make an indentation. The correct viscosity has been achieved when ledges made in the mix stand up on their own.

After the final materials have been added to the mixer or tub, mix for at least three minutes and up to five minutes for the mortar to get ready.

When hand-mixing, be sure all substances are combined before adding water.

To improve the workability of the mixture, you may add chemical plasticizers or masonry cement.

Add dye directly before mixing the mortar if you want it to have a specific color.

For brick fences made of mortar, waterproofing chemicals may be added to the mix to keep them dry.

A Few Other Tips and Warnings

When mixing the mortar, remember that the amount of water added will depend on the type of mortar being mixed and the temperature outside.

Each variety of mortar mix will need a different amount of materials. Make sure you’re using the correct type of mortar mix for the job.

When using cement, it’s best to get fresh unopened bags as the cement that is not sealed will have absorbed moisture from the air and will require an altered water percentage to get the correct viscosity.

You should also not add too much water at one time as this will result in a weak mix.

If the mixture becomes too dry, add small amounts of water until the desired consistency is reached. But do not add more water once the mortar begins to set.

Lastly, you should note that mixed mortar lasts for around 90 minutes, after which it should not be used and thrown away since it begins to lose some of its characteristics.

The Bottom Line

There are many types of mortar mixes available on the market, so make sure you’re using the right one for your project.

The type of mortar you use will be determined by the job and the materials you’re using.

For instance, if you’re working with stone, you’ll need a stronger mix than if you were just using brick.

When mixing mortar, always use clean tools and follow the manufacturer’s instructions.

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