Written by : Engr Sami Ullah Stanikzai (www.civilglobal.com)
In this Article Today i will tell you that what is “Grade of Concrete”.
We have Different Types Of Grade of Concrete The Given List is For Different Grade of Concrete.
Grade of Concrete
GRADE OF CONCRETE DEFINITION.
HERE “M” STANDS FOR MIX AND NUMBER USED FOR THE COMPRESSIVE STRENGTH OF CONCRETE MAY BE IN 28 DAYS.
So it Means that if I say M15 so it means that this grade of concrete strength is 15N/mm2 but this strength of concrete is after 28 days . And for that we have to take the concrete Cubic and than we used Concrete mix ratio M15 Means we used Proportion of Concrete (1:2:4) It mean that (1) is Cement (2) is Sand and (4) is Crush or Aggregate.
When for above grade of Concrete when the (M15) when the 28 days completed than we applied the load on that a Concrete Cubic in compression machine the give image is for that Compression Test.
So for M20 , M25 etc for all these Grade of concrete we used the same method . example if the M25 Grade of concrete So it means that this grade of concrete strength should be 25N/mm2 after 28 days.
Types of grade of concrete:
Nominal Mix : Nominal mix concrete is used for the small scale construction which are simple projects like residential buildings. Where the high strength is not required, so we used the nominal mix concrete. So it mean that the nominal mix concrete used for the normal buildings. And we just take care of factor of safety for quality control problem during concrete construction of any structure. In nominal mix concrete we have M5 , M7.5 , M10 M15 , M20, M25. These grade of concrete is also too much good, but the M15 to M25 these are used for RCC works. Because it his the high strength.
Used of Nominal Mix Concrete in construction works :
I have already explained you that the suitable grad of concrete should be select by the base on the structure design. SO the therefore Nominal Mix Concrete Grades are such as M15, M20, M25 are used for the small project construction where the high strength is not required. so the above Grade of concrete (M15, M20, M25) should be count with Nominal mix concrete.
Design Mix Concrete: The design mix concrete is that which mix proportions can be obtained from various lab tests. And design mix concrete is used for the good quality control when we are selection the materials , Mixing and transportation of concrete. And this kind of Concrete types is used for the Mega projects, where the high strength are required for the project, Than we are able to select this Design mix concrete.
The Design max concrete are used to gain the high strength of concrete to construct the mega project. But the Design mix concrete is too much expensive therefore it used for the high level projects.
Used of Design Mix Concrete :
For mega project construction we used the design mix concrete. Because there are required the high strength of concrete. Therefor we select the higher grade of concrete same like M30, M35 , M30 , M45 etc. Because these proportion of concrete should be design for any mega project by their requirements of project construction.And design mix concrete is used to construct the dams and airport etc. where we required the high strength of concrete so make the good quality of project
Note: For Different Construction works we design the Grade of Concrete that is this Grade of concrete is better for the design work or not. So Strength of concrete is depend on the Grade of concrete . there we used the Different Grade of concrete for the different construction works.
But for most of the Construction works we have to design the Grade of concrete Because For foundation works or for Slab , Beam , column these all are change from each other and these structures can support the different types of load therefor we have to use for any structure different grade of concrete, and we have to also keep the Quality Control for the construction works.