Some materials are used so widely across the world that we don’t take time to focus on what they are. One of those materials is mortar. It is used in every continent and nearly every country. But have you ever taken the time to examine it?
What Is Mortar?
Mortar is a mixture of cement, water, and other materials. It is used to bind bricks, stone, and more, as well as to fill and seal gaps. It can also be used to add decorative patterns to stone, brick, and even wood structures.
History Of Mortar
Mortar has been around for thousands of years. When it was invented, it started out with people learning that they could create a sort of dust with limestone and other materials. They would mix this with clay and water to create a new type of binder.
Throughout time, certain types of mortars began disappearing. In the 1960s, experimentation began once again in the United States, and today, all sorts of mortars are in use. It may have taken time to perfect the different types of mortar, but it was well worth the time.
Difference Between Mortar, Concrete, And Cement
This is where people get confused. We’ve outlined the difference between cement and concrete before. Cement is an ingredient in concrete. While concrete is a combination of cement, water, and gravel.
When it comes to mortar, things are different. Mortar is very similar to concrete only with less, or no gravel at all. It is a binder used when br5icklaying while concrete is a solid, strong material used for other things.
So, both mortar and concrete have cement in them. But when it comes it comes to mortar and concrete, concrete is used for building structures while mortar is used to bind structures.
Types Of Mortar
Although there are many different types of mortar made with different materials, the easiest way to differentiate between them is by a letter on the bag. There are five main types and all are available to the general public.
N-Type Mortar Mix
Withstood PSI – 750
Recommended On – exterior, above-grade, interior, load-bearing, and soft stone
Type N is usually used on exteriors, although it’s fine to use on interiors as well. It works well under intense heat, cold, and in storms. The formula includes 1 part Portland cement, 1 part lime, and 6 parts sand.
Because it is so versatile, it is the most common type of mortar mix used by homeowners and private companies. It is a general purpose mortar that works well for most uses and can be used in place of a mixture of mortar types.
O-Type Mortar Mix
Withstood PSI – 350
Recommended On – interior, non-load-bearing
Type O mortar mix has a rather low compressive strength. It has half the strength of an N-type mix and is only used for interiors. It is generally used for repairs and small interior structures and is the weakest type of mortar.
S-Type Mortar Mix
Withstood PSI – 2000
Recommended On – below grade, masonry foundations, manholes, retaining walls, sewers, patios, pavement
Type S mortar is very strong and has a minimum withstood PSI of 1800. It works for most projects but isn’t normally used on interiors. It is strong enough to drive or walk on, so it is often used in paved walkways.
Type S can also be mixed with other materials for an even stronger grade and withstood PSI. Only one other grade is stronger than it, though it can withstand almost anything. So it is used more often than the other type.
M-Type Mortar Mix
Withstood PSI – 2500+
Recommended On – heavy loads, masonry below grade, foundations, retaining walls, driveways
Type M mortar mix has the highest amount of cement so it is the strongest type that you can get. To be considered M-type, it has to have at least 2,500 psi of compressive strength. But that doesn’t make it perfect.
It isn’t suitable for interiors or visible areas. It works well with natural stone as its texture is similar after it dries and its strength is the same as well.
K- Type Mortar Mix
Withstood PSI – less than 100
Recommended On – restoration
Type K mortar isn’t used often. Its primary use is for restoring old mortar and filling old cracks. It works well for these uses because it’s thin and can fit into cracks and cover surfaces properly as it doesn’t have a thick texture.
Working With Old Mortar
If you want to repoint old mortar, then you don’t need to worry. It’s quite easy and can be done by anyone who knows how to mix mortar. For those who don’t know, repointing is the act of repairing and filling cracks in old brick walls.
Although most mortars used lime historically, today, most mortars used Portland cement due to its strength. However, much of the old mortar in old homes was made with lime, so it isn’t quite as strong as new mortar.
You can strengthen it by adding a layer of new mortar and filling any cracks that you may see. If there is a weak spot, you can even chisel it out and fill the hole with new mortar to strengthen the area.
Although Portland cement is generally recommended, high-grade mortar can actually destroy old, soft bricks and stone. So make sure to use one of the lower-grade mortars that are specified for the job. You can actually look for repointing mortar or make your own.
If you don’t hire someone to help out who knows what they are doing, it’s recommended to use lime mortar as it won’t break down the old structures like Portland cement mortar can.
Remove Damaged Mortar
There are two ways to do this. You can either chisel away small areas that aren’t strong, or take the entire structure down and rebuild it. If you choose to chisel small areas, there’s nothing much left to be said.
But if you want to reconstruct, you’ll need to put a lot of work into it. Start at the top and take the structure apart brick by brick. Chisel each brick or stone out and scrape off any mortar on it.
If you choose to simply remove the top layer and problem areas of the old mortar, then you’ll need to vacuum any holes you make. This isn’t necessary if there isn’t much broken-off mortar but it’s always helpful.
Wet The Area
Mortar won’t stick strongly to dry areas. So wet the area where you’re applying new mortar. Spray the area evenly and let it sit for a minute. Don’t saturate, just moisten it. Use a spray bottle to get a good level of water on it.
Fill The Cracks
Now, use your pointing trowel to fill the gaps. It’s important that the trowel is smaller than the larger gaps so you can fill them properly. Pack the mortar very tightly. If it is overfilled, it’s fine, as you can smooth off the excess later.
Let It Dry Halfway
After the mortar has dried enough that you can barely leave a thumbprint, scrape the excess off and leave a smooth surface. After that, you can finish the facing or leave it as it is. Keep in mind that it will take about a month before the mortar hardens all the way.
How To Make Mortar
Because mortars are primarily natural, they are quite easy to make yourself. While it is generally recommended to buy mortar mix, some people love to do things themselves and start from scratch, adding their own touch.
Here are the three main ways to make mortar.
Portland Cement, Lime and Sand
This is the historical method and still works quite well. If you want to make a strong Type S mortar, this is what you’d use.
- 1 bag of Portland cement
- ½ bag of hydrated type S lime
- 28 shovelfuls of masonry sand
- 7 to 8 gallons of water
How To Mix:
Start off with water. Put 2/3 to 3/4 of the water into the mixer. Then add the cement and lime. Lastly, add the sand. Then, use the last bit of water slowly until it is the right texture. Mix for about five minutes.
If you want stiff, strong mortar, use less water. If you want thinner, wet mortar, use more water. Always opt for not adding enough water because you can always add more later. But you can’t take any water away.
Masonry Mortar is just like mixing your own only it has the cement and lime already mixed in so it’s much easier to use. If you want the standard Type S mortar with Masonry Mortar, this is what you do.
- 1 bag of Masonry Cement
- 18 to 20 shovelfuls of Masonry Sand
- 5 Gallons of water
How To Mix:
Start off with water. Put 2/3 to 3/4 of the water into the mixer. Then add the sand. Just like before, use part of the remaining water slowly until it is the right texture. Mix for about five minutes.
This is by far the easiest mortar to make. It is just like masonry mortar only has the sand added too. So all you have to do is add water.
- 1 bag of mix
- 5 to 6 quarts of water
How to Mix:
Put 2/3 to 3/4 of the water into the mixer. Add the mortar mix. Then add remaining water as needed. For this mix, let it mix for a few minutes and then turn it off and let it fall. Then turn it on and mix for a few more minutes. If you don’t have a mixer, feel free to use a wheelbarrow and mixing tools. It works just as well but is much harder work.