# Why we use 150 mm size cube for compressive strength testing

#### Dnyan Deshmukh

Staff member
Why we use 150mm size cube for compressive strength testing.
Hi all civil engineer,

when i was in collage i wonder that all constructions site have the cube size of 150mm x 150mm x 150mm.

IS 516 do mention that we should use 150mm size cube or 100mm size cube as alternative when maximum size of aggregates do not exceed 20mm.

Max construction site have the cube testing machine of capacity 100 ton / 1000kn. and our compressive strength calculation is load / area i.e.- n/mm2

if you are checking M30 concrete and you requires min. comp strength of 33n/mm2 and the size of cube is 150mm then the load required to get this much strength is 742.5 Kn. if you use cube of size 300mm the load require becomes 2970 kn, this is practically not possible as to crush the cube u require 3000kn/300 ton capacity machine. When the applied load is much more the additional safety factors need to be increase because when cube fails under such loads may hit anything in room with bullet speed.

Also casting of this size cube and handling is not easy.

for feasibility, safety and ease of work we use 150mm size cubes.

if you have a machine with less capacity and load to crush the cube is more than the capacity of machine you can reduce the size of cube further to 100mm.

This you can do when you go for high grade concretes M50 and above and your machine capacity is 100 ton.

Nice information

#### RAJJOGISRI

##### Senior Member
If we have to check for M100???

#### kamesh

##### Newbie
150 mm is the ideal size for cube making. It is big enough to take coarse grains of 20 mm size and small enough to be handled easily.

If the cube is too big, handling will be difficult. Also, the load required to test will be much higher which is another problem.

If cube is too small, we won’t get true strength due to large coarse grain present in concrete which create anisotropy in concrete.

150 mm is roughly half foot, so it is good round number to use.

But we use other cube sizes for different specific purposes like we test 100 mm cubes for concrete made of 10 mm coarse grain material. Also, we test 400 mm size cubes for concrete used in airports.

Apart from cubes, we use cylinders too for concrete testing.

#### anbarasan

Good information

##### Apprentice
Why we use 150mm size cube for compressive strength testing.
Hi all civil engineer,

when i was in collage i wonder that all constructions site have the cube size of 150mm x 150mm x 150mm.

IS 516 do mention that we should use 150mm size cube or 100mm size cube as alternative when maximum size of aggregates do not exceed 20mm.

Max construction site have the cube testing machine of capacity 100 ton / 1000kn. and our compressive strength calculation is load / area i.e.- n/mm2

if you are checking M30 concrete and you requires min. comp strength of 33n/mm2 and the size of cube is 150mm then the load required to get this much strength is 742.5 Kn. if you use cube of size 300mm the load require becomes 2970 kn, this is practically not possible as to crush the cube u require 3000kn/300 ton capacity machine. When the applied load is much more the additional safety factors need to be increase because when cube fails under such loads may hit anything in room with bullet speed.

Also casting of this size cube and handling is not easy.

for feasibility, safety and ease of work we use 150mm size cubes.

if you have a machine with less capacity and load to crush the cube is more than the capacity of machine you can reduce the size of cube further to 100mm.

This you can do when you go for high grade concretes M50 and above and your machine capacity is 100 ton.
Very useful information

#### Reddy

##### Senior Member
Thank you sir nice information

#### palanisamy engineer

##### Junior Member
Is all this a
150 mm is the ideal size for cube making. It is big enough to take coarse grains of 20 mm size and small enough to be handled easily.

If the cube is too big, handling will be difficult. Also, the load required to test will be much higher which is another problem.

If cube is too small, we won’t get true strength due to large coarse grain present in concrete which create anisotropy in concrete.

150 mm is roughly half foot, so it is good round number to use.

But we use other cube sizes for different specific purposes like we test 100 mm cubes for concrete made of 10 mm coarse grain material. Also, we test 400 mm size cubes for concrete used in airports.

Apart from cubes, we use cylinders too for concrete testing.
Is all this crt?

msansari

#### palanisamy engineer

##### Junior Member
Nice information sir thank you

Why we use 150mm size cube for compressive strength testing.
Hi all civil engineer,

when i was in collage i wonder that all constructions site have the cube size of 150mm x 150mm x 150mm.

IS 516 do mention that we should use 150mm size cube or 100mm size cube as alternative when maximum size of aggregates do not exceed 20mm.

Max construction site have the cube testing machine of capacity 100 ton / 1000kn. and our compressive strength calculation is load / area i.e.- n/mm2

if you are checking M30 concrete and you requires min. comp strength of 33n/mm2 and the size of cube is 150mm then the load required to get this much strength is 742.5 Kn. if you use cube of size 300mm the load require becomes 2970 kn, this is practically not possible as to crush the cube u require 3000kn/300 ton capacity machine. When the applied load is much more the additional safety factors need to be increase because when cube fails under such loads may hit anything in room with bullet speed.

Also casting of this size cube and handling is not easy.

for feasibility, safety and ease of work we use 150mm size cubes.

if you have a machine with less capacity and load to crush the cube is more than the capacity of machine you can reduce the size of cube further to 100mm.

This you can do when you go for high grade concretes M50 and above and your machine capacity is 100 ton.

Doubt cleared

#### VIDHYA SAGAR

##### Senior Member
what is the purpose for cylindrical casting?

nice information

#### Zaid

##### Newbie
i think so, that the internal friction of cube is symmetric in all direction so it is preferable.

#### Kaushal Kishore

##### Newbie
IS: 456-2000 specified that the acceptance cretaria of concrete strength shall be 28 days compressive strength of 150 mm cubes average value of 3 cubes, the variation strength of these 3 cubes shall not be more than +/- 15 percent of average strength. For further details please visit Google site and log in to Acceptance cretaria of concrete strength as per IS: 456-2000 by Er Kaushal Kishore and also Concrete cube testing and concrete mix design by Er Kaushal Kishore

#### Valmiki

##### Senior Member
Sir,
Very well explained,
have a query w.r.t cube strength result for M30 after 28 Days we are obtained M45 result and Mix design is 270 Kg of cement and 110 Kg of GGBS / Per Cum for M30, can we reduce the cement content by 15 Kg to limit the over stengnth of cubes.

#### Ramesh2544

##### Apprentice
Why we use 150mm size cube for compressive strength testing.
Hi all civil engineer,

when i was in collage i wonder that all constructions site have the cube size of 150mm x 150mm x 150mm.

IS 516 do mention that we should use 150mm size cube or 100mm size cube as alternative when maximum size of aggregates do not exceed 20mm.

Max construction site have the cube testing machine of capacity 100 ton / 1000kn. and our compressive strength calculation is load / area i.e.- n/mm2

if you are checking M30 concrete and you requires min. comp strength of 33n/mm2 and the size of cube is 150mm then the load required to get this much strength is 742.5 Kn. if you use cube of size 300mm the load require becomes 2970 kn, this is practically not possible as to crush the cube u require 3000kn/300 ton capacity machine. When the applied load is much more the additional safety factors need to be increase because when cube fails under such loads may hit anything in room with bullet speed.

Also casting of this size cube and handling is not easy.

for feasibility, safety and ease of work we use 150mm size cubes.

if you have a machine with less capacity and load to crush the cube is more than the capacity of machine you can reduce the size of cube further to 100mm.

This you can do when you go for high grade concretes M50 and above and your machine capacity is 100 ton.
YOU ARE REALLY GREAT SIR. GIVING GOOD KNOWLEDGE.

Dnyan Deshmukh

#### Ramesh2544

##### Apprentice
Sir,
Very well explained,
have a query w.r.t cube strength result for M30 after 28 Days we are obtained M45 result and Mix design is 270 Kg of cement and 110 Kg of GGBS / Per Cum for M30, can we reduce the cement content by 15 Kg to limit the over stengnth of cubes.
YES YOU CAN REDUCE CEMENT CONTENT, BUT ACCORDING TO IS;456 YOU SHOULD MAINTAIN MINIMUM CEMENT CONTENT ALSO.

#### Dnyan Deshmukh

Staff member
Sir,
Very well explained,
have a query w.r.t cube strength result for M30 after 28 Days we are obtained M45 result and Mix design is 270 Kg of cement and 110 Kg of GGBS / Per Cum for M30, can we reduce the cement content by 15 Kg to limit the over stengnth of cubes.
Yes, you can optimize mix further by reducing cement content provided you get desired results after conducting trials.

#### Karthick P

##### Senior Member
Why we use 150mm size cube for compressive strength testing.
Hi all civil engineer,

when i was in collage i wonder that all constructions site have the cube size of 150mm x 150mm x 150mm.

IS 516 do mention that we should use 150mm size cube or 100mm size cube as alternative when maximum size of aggregates do not exceed 20mm.

Max construction site have the cube testing machine of capacity 100 ton / 1000kn. and our compressive strength calculation is load / area i.e.- n/mm2

if you are checking M30 concrete and you requires min. comp strength of 33n/mm2 and the size of cube is 150mm then the load required to get this much strength is 742.5 Kn. if you use cube of size 300mm the load require becomes 2970 kn, this is practically not possible as to crush the cube u require 3000kn/300 ton capacity machine. When the applied load is much more the additional safety factors need to be increase because when cube fails under such loads may hit anything in room with bullet speed.

Also casting of this size cube and handling is not easy.

for feasibility, safety and ease of work we use 150mm size cubes.

if you have a machine with less capacity and load to crush the cube is more than the capacity of machine you can reduce the size of cube further to 100mm.

This you can do when you go for high grade concretes M50 and above and your machine capacity is 100 ton.

Refer IS code 516 (1959) Clauses 2.8

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#### Dnyan Deshmukh

Staff member
Refer IS code 516 (1959) Clauses 2.8
Thank You did corrections to my word.

Karthick P

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