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What is C 20/25 Concrete?

How strong is your Concrete? Looking for the thickness of Pipes? Cylindrical Pipes? Box Culverts? U-Drains? What is the strength class of your Concrete?

Concrete is usually classified with respect to the characteristic compressive strength of the concrete determined on 150 mm diameter by 300 mm cylinders (fck,cyl) or on 150 mm cubes at 28 days of hardening (curing). The characteristic compressive strength, measured in N/mm2 or MPa, is the compressive strength at 28 days which 95% of all strength determinations must either be equal to or greater than. The standard classification, as used in the European Standard EN 206-2 and adopted in many other international and national standards, is to denote the characteristic compressive strength classes by the notation C X/Y (where X is the 28 days’ compressive strength of 150 mm diameter by 300 mm cylinders and Y is the 28 days’ compressive strength if the same concrete was cast as 150 mm cubes).

For instance, when concrete is classified as C 20/25, it implies that for such concrete 95% of all compressive strength determinations would have a 28 days’ compressive strength greater than or equal to 20 N/mm2 when the concrete is cast into 150 mm diameter by 300 mm cylinders or greater than or equal to 25 N/mm2 when the concrete is tested as 150 mm cubes. Typical uses for this class of concrete are in the formation of internal floor slabs, driveways, garages, and sheds.

Strength class of concrete is chosen to satisfy structural integrity and other performance factors during the service life of concrete. Concrete must necessarily be designed, taking into consideration factors such as the properties of the component materials (i.e. cement, coarse and fine aggregates, and admixtures/additives), the water/cement ratio, environmental exposure conditions, intended use etc. in order to arrive at a suitable composition which meets a particular targeted strength class for the job at hand.


For a full price list of precast concrete products please contact RCP on +233 27 776 2256. You can buy the following Concrete Products in Ghana from Regimanuel Concrete Products Ltd. (RCP):

Box Culverts
Construction Blocks
Cylindrical Pipes
Electrical & Fence Poles
Granite (Chippings)
Interlocking Pavement Blocks
Kerb Stones
Manhole & Pipes
Rectangular Pavement Blocks
Rialta Pavement Blocks
Septic Tank
Slope Protection & Retaining Walls
U-Drains & Slabs… etc..

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