The Three Main Strength Classes of Cement
In this post, you are going to learn the three main strength classes of cement and also the different types of cement based on composition used in building and construction
GENERAL CONSTRUCTION
The Three Main Strength Classes of Cement
Table of contents
The core concept or idea
What are the different types of cement and their uses?
a) 32.5
b) 42.5
c) 52.5
Where do we use each class of cement in construction?
Which cement is best for waterlogging areas?
What is the difference between 32.5, 42.5, and 52.5 cement?
What is the effect of cement type on the compressive strength of concrete?
How do you choose the right kind of cement for your project?
Where do we use cement with an R, and where do we use cement with an N?
Chemical Composition of Cement
a) CEM I
b) CEM II
c) CEM III
d) CEM IV
e) CEM IV
Types of Portland cement and their uses
Table showing cement types, composition, grouping, and notation
Understanding the different types of cement with examples
What is the difference between white cement and ordinary cement?
What determines the strength of cement?
What is the difference between white cement and ordinary cement?
Conclusion
Frequently Asked Questions
Core concept or idea
In this post, you are going to learn the three main strength classes of cement and also the different types of cement based on composition used in building and construction. By the end of this post, you will have a clear understanding of which class of cement is stronger than the others and where to use each class at different stages of construction.
As a civil engineer with years of experience in building and construction, I have worked extensively with various types of cement and understand their role in construction. That’s why the information provided in this post is experience-based, tested, and trusted, and you can rely on it when choosing the right kind of cement for your project.
What are the different types of cement and their uses?
There are three main strength classes of cement: 32.5, 42.5, and 52.5. The "R" or "N" following these numbers refers to the type of strength development. "R" stands for rapid or early strength development, while "N" stands for normal or standard strength development.
Where do we use each class of cement in construction?
32.5 Cement
Cement with a strength class of 32.5 is considered to be of low strength, and it is commonly used in general applications where high initial strength is not required. For example, when doing masonry brickwork or block work, plastering and rendering, building perimeter walls, and for all works in bungalow houses. This is the best cement for home construction works that are simple.
42.5 Cement
Cement with a strength class of 42.5 is of mid-level strength. It is typically used in applications where at least 30 newtons per mm squared of compression strength is required. This includes all structural work in storeyed houses, such as pads or footings, columns, slabs, beams, staircases, and lift shear walls.
Which cement is best for waterlogging areas?
When building in swamps and other waterlogging areas, it is recommended to use cement with a strength class of 42.5 R (rapid) instead of 42.5 N (normal). The "R" denotes rapid strength or setting fast, which allows the cement to attain its initial strength.
52.5
Cement with a strength class of 52.5 is considered to be of the highest strength and can create a high-strength concrete mix. It is used in applications where high initial strength is so much required. This includes heavy structures like bridges, road construction, and precast concrete structures; terrazzo flooring for high-traffic areas, for example, in churches, hospitals, schools, shopping malls, airports, dancehall clubs, or cinema halls, among others.
What is the difference between 32.5, 42.5, and 52.5 cement?
What is the effect of cement type on the compressive strength of concrete?
The compressive strength of concrete simply refers to its capacity or ability to withstand loads without failure. The performance or strength of concrete is simply determined by the type of cement used in the mixture. Concrete will have low strength when 32.5 class cement is used, medium strength when 42.5 class cement is used, and high strength when 52.5 class cement is used.
The compressive strength reached by 42.5N and 42.5R will be the same once completely cured; however, 42.5R will reach a higher initial compressive strength than 42.5N; same for all classes.
In simple terms, 42.5R will set faster than 42.5N, and also 32.5R will set faster or reach a higher initial compressive strength than 32.5N; same for all classes.
How do you choose the right kind of cement for your project?
When choosing the right cement for your project, it is always required to consider the specific requirements and strength needed. The right cement choice ensures the design strength of the building is attained and, most importantly, the health and safety of the users are taken into account.
Structural Work
For structural work in storeyed houses, including pads or footings, columns, slabs, beams, staircases, lift shear walls, and other elements that make up a structure of a building, cement with a strength class of 42.5 (either R or N) is recommended.
Where do we use cement with an R, and where do we use cement with an N?
When working in swamps or waterlogged areas, it is advised to use cement with an R instead of the one with an N.
Water Projects
For water projects, such as water drainages, footings in swamps, or working in waterlogged areas, cement with a strength class of 42.5 R or 52.5 R should be used. These types of cement set faster and are able to withstand heavy loads without concrete failure. 52.5R is commonly used in marine structures.
Precast Concrete Structures
For heavy structures like bridges and precast concrete structures, cement with a strength class of 52.5 R or N is recommended. The high initial strength of these cements ensures the durability and stability of the structures.
Chemical Composition of Cement
Cement has five main types based on composition: CEM I, CEM II, CEM III, CEM IV, CEM V.
CEM I
CEM I is a Portland cement that contains 92% to 100% clinker. Clinker is a mixture of limestone and other minerals that are heated and rapidly cooled to produce cement.
CEM II
CEM II is also Portland cement but contains a lower percentage of clinker, ranging from 64% to 94%. The remaining percentage is composed of slag and limestone.
CEM III CEM III is blast furnace cement, which has a range of 5% to 64% clinker. Blast furnace cement is a type of cement produced by grinding granulated blast furnace slag.
CEM IV
CEM IV is pozzolanic cement that contains 45% to 89% clinker. Pozzolanic cement is a type of cement produced by grinding pozzolanic materials such as fly ash, silica fume, volcanic ash, and metakoalin, among others.
CEM V
CEM V is composite cement that contains 20% to 64% clinker. Composite cement is a type of cement that combines different types of materials.
Types of Portland cement and their uses
It is important to note that all Portland cements (CEM I and CEM II) are stronger than other types of cement, and we use them where middle and high strength of the structure is needed.
Therefore, when choosing cement for your project, consider the strength class and composition to ensure the desired strength is achieved.
I have prepared a simple table below which to make things so easy and can be understood by everyone.
Understanding the different types of cement with examples
From the understanding that we have from the table, we can clearly confirm that these cements in the picture above fall under CEM II cement, notation BP, which is under grouping Portland pozzolan cement and with 65-79% clinker.
The cement above is a CEM I CEMENT, and by seeing this CEM I, that simply means it has 92-100% clinker and it’s a Portland cement.
Clicker is the strong part in cement, meaning when cement has 92-100% clinker, it simply means it’s very strong. I took a picture from one of the cements we used when doing terrazzo flooring, and we are going to use it to summarise all we have studied in this article.
You can see from a table on this white cement bag that it is a CEM I type of cement. It shows that its percentage of clinker is 92-94%, with standard strength 52.5 N – N meaning standard or normal strength development; it’s a Portland cement and its white cement
This is another example here below
It shows CEM IV, meaning it’s a pozzolanic cement. It also shows B(P) under CEM IV meaning it has 45-64% clinker and that simply means it’s not strong
Now that you have learnt the different types of cement, make it a task to look at bags of cement in your surrounding so as to understand the concept practically
What is the difference between white cement and ordinary cement?
What determines the strength of cement?
The strength of cement also depends on the percentage of clinker in the cement; the higher the percentage of clicker, the higher the strength, irrespective of whether it is white cement or ordinary cement.
The strength of cement also depends on its chemical composition, ranging from CEM I to CEM V (CEM I, CEM II, CEM III, CEM IV, and CEM V). CEM I is the strongest, whereas CEM V is the weakest.
The strength of cement also depends on the grouping of cement. Portland cements are the strongest (CEM I and CEM I).Blast furnace cements are of medium strength (CEM III).Pozollanic cements are weak (CEM IV and CEM V).
Conclusion
Understanding the right kind of cement to be used at different stages for your construction project is a crucial step that you should never skip for structural strength to ensure the safety of the users.
Avoid the common mistake of purchasing any type of cement without considering the specific requirements of the project. Take the time to assess the strength class and composition of the cement to ensure that you choose the right kind of cement.
Frequently Asked Questions
What are the 3 main classes of cement?
The 2 main classes of cement are 32.5, 42.5, and 42.5, followed by an R or N.
What are the 5 classifications of cement?
The 5 classifications of cement are CEM I, CEM II, CHEM III, CHEM IV, and CHEM V.CEM I is a Portland cement, CEM II is a Portland cement, CEM III is a blast furnace cement, and CEM IV is a pozzolanic cement.
CEM V is composite cement. What is the difference between ordinary Portland cement OPC and Portland pozzolan cement PPC?
Ordinary Portland cement OPC is a CEM1 type of cement and has a strong part of cement called clinker ranging from 95-100%, whereas Portland pozzolan cement is a CEM II type of cement and has clinker ranging from 65-94%, meaning OPC is stronger than PPC.
What is rapid-hardening cement, and where is it used?
Rapid cement is a type of cement that attains its initial strength and sets fast, and it is used for concreting applications in waterlogged structures and precast concrete. It can also be used for fast-setting cement for emergency repairs or any other applications that require high initial strength.
What is Portland slag cement?
Portland slag cement is a CEM II type of cement that has clinker ranging from 65 to 94% and is commonly used when building sewage systems, coastal areas, and general marine construction.
Why is white cement more expensive than ordinary cement?
White cement is more expensive than ordinary Portland cement due to its manufacturing process, which requires more additional steps. It is commonly used in decorative applications such as white concrete, tiling, terrazzo flooring, and exterior finishes.
I also created a video version with a more detailed explanation. You can check it out here