In the European Standard (EC2), concrete grades are classified by a combination of a letter and a number. The letter indicates the characteristic strength class, and the number denotes the characteristic cylinder strength in megapascals (MPa). Here are some common concrete grades:
1. C20/25: Characteristic strength of 20 MPa compressive strength and 25 MPa tensile strength.
2. C25/30: Characteristic strength of 25 MPa compressive strength and 30 MPa tensile strength.
3. C30/37: Characteristic strength of 30 MPa compressive strength and 37 MPa tensile strength.
4. C35/45: Characteristic strength of 35 MPa compressive strength and 45 MPa tensile strength.
5. C40/50: Characteristic strength of 40 MPa compressive strength and 50 MPa tensile strength.
These grades are specified for various structural applications, and the numbers represent the cylinder strength. The higher the number, the stronger the concrete.
Concrete grade mention in Eurocode 2 and EN 206-1, According to European standard EC2, as per European standard, concrete grade represented as C12/15, C16/20, C20/25, C30/37, C35/45, C40/50, C45/55, C50/60, C55/67, C60/75, C70/85, C80/95 and C90/105. For example, C16/20, It is indicated as C, which C is stand for concrete strength class followed by a numerical figure 16, which is compressive strength of concrete is 16MPa after 28 days of mixing on axial compression test on cylinder shape with 15cm dia and 30cm length cylinder follow by numerical figure 20, which is compressive strength of concrete is 20MPa after 28 days of mixing on axial compression test on cube concrete block shape with cube size 15cm × 15cm × 15cm.
Characteristic strength of concrete is their compressive strength which can be determined by axial compression test on cubic concrete block or cylinder shape. If Compression test is carried on cubic concrete block, when tested with cube size 15cm × 15cm × 15cm, that’s known as Cubic test and their strength is called cubic strength. And compression test is carried on cylinder shaped concrete block, when tested with 15cm dia and 30cm length of cylinder, that is known as cylinder test and their strength is called cylinder strength.
Value of cube strength and cylinder strength are different for same mix. Value of cube strength is higher than cylinder strength. Using Thumb Rule, value of cube strength is is 1.25 times higher than cylinder strength.
Cube strength = 1.25 × cylinder strength
European Standard (EC2) codes concrete grade generally refers both, cube test and cylinder test, for finding out compressive strength of different mix of concrete at 28 days after mixing. In this article we read about types of concrete grade and their compressive strength as per European Standard.
Types of concrete grade and their compressive strength as per European Standard (EC2)
Concrete grade mention in Eurocode 2 and EN 206-1, According to European standard (EC2), concrete grade is indicated as C16/20, It is indicated as C, which C is stand for concrete strength class followed by a numerical figure 16, which is compressive strength of concrete is 16MPa after 28 days of mixing on axial compression test on cylinder shape with 15cm dia and 30cm length cylinder follow by numerical figure 20, which is compressive strength of concrete is 20MPa after 28 days of mixing on axial compression test on cube concrete block shape with cube size 15cm × 15cm × 15cm.
What are the grades of concrete and their compressive strength accoding to Eurocode 2
As we know that concrete are made of mixing of cement, sand and aggregate in required proportion. What are the grades of concrete, according to EC2 (European standard), the grades of concrete represented as C12/15, C16/20, C20/25 is known as normal grade of concrete have secondary uses, C30/37, C35/45, C40/50 is known as standard grade of concrete which are generally used and C50/60, C55/67, C60/75, C70/85, C80/95 is known as high strength concrete grade used for special construction.
C12/15 concrete grade
● C12/15 concrete grade:– This is normal grade of concrete have secondary uses, according to European standard, strength of concrete and mix of Portland stone cement, fine aggregate and coarse aggregate, design according to cube test and cylinder test. In C12/15 concrete grade, C indicates concrete strength class, numerical figure 12 represent it’s characteristics of compressive strength (fck) on cylinder test that is 12MPa and numerical figure 15 represent it’s characteristics of compressive strength (fck) on cube test that is 15MPa. So compressive strength (fck) value of C12/15 concrete grade is 12MPa based on cylinder test and 15MPa based on cube test.
According to Eurocode 2, fck value for C12/15 concrete grade are as follows:-
1) 12N/mm2 or 12MPa on cylinder test
2) 15N/mm2 or 15MPa on cube test.
C16/20 concrete grade
● C16/20 concrete grade:- This is normal grade of concrete have secondary uses, according to European standard, strength of concrete and mix of Portland stone cement, fine aggregate and coarse aggregate, design according to cube test and cylinder test. In C16/20 concrete grade, C indicates concrete strength class, numerical figure 16 represent it’s characteristics of compressive strength (fck) on cylinder test that is 16MPa and numerical figure 20 represent it’s characteristics of compressive strength (fck) on cube test that is 20MPa. So compressive strength (fck) value of C16/30 concrete grade is 16MPa based on cylinder test and 30MPa based on cube test.
According to Eurocode 2, fck value for C16/20 concrete grade are as follows:-
1) 16N/mm2 or 16MPa on cylinder test
2) 20N/mm2 or 20MPa on cube test.
C20/25 concrete grade
● C20/25 concrete grade:- This is normal grade of concrete have secondary uses, it is recommended for construction of load bearing building, according to European standard, strength of concrete and mix of Portland stone cement, fine aggregate and coarse aggregate, design according to cube test and cylinder test. In C20/25 concrete grade, C indicates concrete strength class, numerical figure 20 represent it’s characteristics of compressive strength (fck) on cylinder test that is 20MPa and numerical figure 25 represent it’s characteristics of compressive strength (fck) on cube test that is 25MPa. So compressive strength (fck) value of C20/25 concrete grade is 20MPa based on cylinder test and 25MPa based on cube test.
According to Eurocode 2, fck value for C20/25 concrete grade are as follows:-
1) 20N/mm2 or 20MPa on cylinder test
2) 25N/mm2 or 25MPa on cube test.
C25/30 concrete grade
● C25/30 concrete grade:- This is normal grade of concrete have secondary uses, it is recommended for construction of load bearing building structure member of beam, column & Foundation, according to European standard, strength of concrete and mix of Portland stone cement, fine aggregate and coarse aggregate, design according to cube test and cylinder test. In C25/30 concrete grade, C indicates concrete strength class, numerical figure 25 represent it’s characteristics of compressive strength (fck) on cylinder test that is 25MPa and numerical figure 30 represent it’s characteristics of compressive strength (fck) on cube test that is 30MPa. So compressive strength (fck) value of C25/30 concrete grade is 25MPa based on cylinder test and 30MPa based on cube test.
According to Eurocode 2, fck value for C25/30 concrete grade are as follows:-
1) 25N/mm2 or 25MPa on cylinder test
2) 30N/mm2 or 30MPa on cube test.
C30/37 concrete grade
● C30/37 concrete grade:– This is normal grade of concrete have secondary uses, it is recommended for construction of load bearing building structure member of beam, column & Foundation, basement, according to European standard, strength of concrete and mix of Portland stone cement, fine aggregate and coarse aggregate, design according to cube test and cylinder test. In C30/37 concrete grade, C indicates concrete strength class, numerical figure 30 represent it’s characteristics of compressive strength (fck) on cylinder test that is 30MPa and numerical figure 37 represent it’s characteristics of compressive strength (fck) on cube test that is 37MPa. So compressive strength (fck) value of C30/37 concrete grade is 30MPa based on cylinder test and 37MPa based on cube test.
According to Eurocode 2, fck value for C25/30 concrete grade are as follows:-
1) 25N/mm2 or 25MPa on cylinder test
2) 30N/mm2 or 30MPa on cube test.
Others higher grade concrete C35/45, C40/50, C45/55, C50/60, C55/67, C60/75, C70/85, C80/95 and C90/105 are used in extreme environmental condition, sea side condition, formation of septic tank and water tank, and basement formation, bridge & dams formation and heavy loaded structural commercial and industrial building, mostly high rise building, it is used for special uses.
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Types of concrete grade and their strength as per American Standard (ACI)
Types of concrete grade and their strength as per Australian Standard (AS)
Types of concrete grade and their ratio as per British Standard (BS)
Concrete grade C25/30 meaning
As per British Standards, C25/30 concrete grade means the concrete having a characteristic compressive cube strength of 30 N/mm^2. The same concrete would have a characteristic strength of 25 N/mm^2 at 28 days if cylinders were used for testing, as in certain European countries.
Concrete grade C20/25 meaning
As per British Standards, C20/25 concrete grade means the concrete having a characteristic compressive cube strength of 25 N/mm^2. The same concrete would have a characteristic strength of 20 N/mm^2 at 28 days if cylinders were used for testing, as in certain European countries.
Concrete grade C32/40 meaning
As per British Standards, C32/40 concrete grade means the concrete having a characteristic compressive cube strength of 40 N/mm^2. The same concrete would have a characteristic strength of 32 N/mm^2 at 28 days if cylinders were used for testing, as in certain European countries.
Concrete grade C28/35 meaning
As per British Standards, C28/35 concrete grade means the concrete having a characteristic compressive cube strength of 35 N/mm^2. The same concrete would have a characteristic strength of 28 N/mm^2 at 28 days if cylinders were used for testing, as in certain European countries.
Concrete grade C16/20 meaning
As per British Standards, C16/20 concrete grade means the concrete having a characteristic compressive cube strength of 20 N/mm^2. The same concrete would have a characteristic strength of 16 N/mm^2 at 28 days if cylinders were used for testing, as in certain European countries.
Concrete grade C12/15 meaning
As per British Standards, C12/15 concrete grade means the concrete having a characteristic compressive cube strength of 15 N/mm^2. The same concrete would have a characteristic strength of 12 N/mm^2 at 28 days if cylinders were used for testing, as in certain European countries.