If you are working with stone and masonry, then you do of course need to bind the various pieces together. Two very common binders that may be used for this purpose are hydraulic cement and mortar.
With that being said, they are not the same things, and you need to know the differences between them before you choose one or the other, so let’s figure this out right now.
Hydraulic Cement and Mortar: The Basics
Before we talk about both the similarities and differences between mortar and hydraulic cement, let’s first figure out what both of them are.
What Is Hydraulic Cement?
Hydraulic cement is a specific type of cement, with one of the main characteristics of it being that it has the ability to cure when wet, even submerged. The main purpose of this type of cement is for structures and buildings that are often or always in contact with water. It is waterproof.
It is used to prevent water leaks in concrete structures, as well as masonry structures. Hydraulic cement is made out of a variety of components including alite, belite, celite, and brownmillerite. The alite and belite help produce great strength when the mixture is cured, and the latter of the ingredients help keep it in its initial liquid state before use.
What Is Mortar?
Technically speaking, mortar is defined as a workable paste that hardens and is used to bind building blocks such as concrete masonry units, bricks, and stones, and to fill in the gaps between pieces of masonry.
Mortar is a mixture of sand and cement, usually Portland cement (a type of hydraulic cement that can cure when wet, and even when underwater), and usually some other materials such as aggregates. The main purpose of mortar is for building walls out of masonry.
Similarities of Hydraulic Cement and Mortar
Now that we know what both hydraulic cement and mortar are, let’s figure out what makes them similar to each other.
1. Both Feature Cement
OK, so when it comes to the composition of both hydraulic cement and mortar, there are of course differences, but with that being said, both are made with cement. Hydraulic cement is obviously made with cement, which is generally Portland cement. Although Mortar does also contain aggregates and sand, it is also made with Portland cement. Portland Cement is the main binding agent in both of these building materials.
2. Both Are Common Building Materials
Although the applications of both of these materials are different, they are both common building materials that are used when working with stone, masonry, and concrete. They don’t have the exact same applications, but they are both used for masonry projects.
3. Both Can Cure Underwater
One of the main benefits that you get with hydraulic cement is that it does have the ability to cure underwater or when just very wet. Seeing as mortar is usually also made with Portland hydraulic cement, it also has the ability to cure when wet or even when totally submerged.
4. Both Are Water-Resistant
Moreover, hydraulic cement is also totally waterproof, which is why it is often used to stop leaks from occurring, especially for buildings and structures that are often exposed to water or are even underwater. Although mortar is not used for the exact same applications, it is used for building walls, and in this case, it is water-resistant. Using mortar to join bricks will prevent water from getting in between the bricks.
5. Both Don’t Work Well in the Cold
Although mortar may work a little better in the cold, the simple fact of the matter is that both of these building materials should not be used in freezing temperatures because they will not cure properly. On that same note, both of these building materials also don’t work too well in extreme heat.
6. Curing Process
Now, we don’t want to get into the science of it here because it can be quite complicated, but with that being said, due to the fact that mortar is made with Portland cement, a specific type of hydraulic cement, the curing process for both of these building substances is the same.
Differences Between Hydraulic Cement and Mortar
Now that we know what the similarities between the two are, let’s talk about the differences between them.
1. Bonding Capabilities
Portland cement is ideal for use with a variety of stones and masonry materials, but with that being said, it really doesn’t bond concrete very well, and it doesn’t stick that well to other materials either. Specifically, when it comes to concrete, Portland cement or hydraulic cement does not have the best bonding capabilities. Mortar, on the other hand, works really well for all types of stone, brick, concrete, and masonry in general.
2. Working Time
One thing that is not too great about hydraulic cement is the fact that it only allows for a 15-minute window between mixing and use. It starts to harden and cure very quickly. Mortar, on the other hand, can take several hours if not up to half a day to start to harden, which means that you have much more time to work with it.
3. Thickness
Another basic difference between these two building materials is that hydraulic cement tends to be fairly thin, whereas mortar is much thicker. Although hydraulic cement can be used on vertical surfaces, it may run down a bit whereas mortar should not run down.
4. Strength
What you also need to know here is that although hydraulic cement does have its uses, the fact of the matter is that cement on its own is fairly weak, especially when compared to something like mortar. You wouldn’t use hydraulic cement to build a wall out of bricks. Mortar would be the material of choice here.
5. One Is Totally Waterproof
What is important to note here is that hydraulic cement is totally waterproof. Although mortar does have hydraulic cement in it, due to the fact that it is mixed with other aggregates, it is not totally waterproof. Of course, mortar is very water-resistant, but over time it will start to wear down and let water in.
Hydraulic Cement vs. Mortar: Which of the Two Should You Use?
The bottom line here is that if you are building a wall out of bricks, stone, or other types of masonry, then it is mortar that you want to go with. However, if you are building something that requires great waterproofing, then it is hydraulic cement that you need to go with.
Just keep in mind that hydraulic cement really isn’t designed to be structural in nature at all, so it’s not something that you would use to build walls. Instead, hydraulic cement is something that you would use to fill gaps and cracks to prevent water from coming in or going out.
Summary
Now that you know what the differences between mortar and hydraulic cement are, you can make an informed decision between the two for your next project.