G15 means compressive strength of 15 N/mm

G20 means compressive strength of 20 N/mm

G25 means compressive strength of 25 N/mm

G30 means compressive strength of 30 N/mm

G40 means compressive strength of 40 N/mm

G50 means compressive strength of 50 N/mm

ASTM C 31 = Standard Practice for Making and Curing Concrete Test Specimens in the Field

ASTM C 39 = Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens

However, we can use the following ratios for small jobs.

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Deformed Bar was previously called Y-Bar e.g., Y12, Y16, etc.,

but through product improvements the tempcore strength was increased (now 500Mpa),

and is now denoted as N-Bar e.g., N12, N16, N20, N24, N28, N32, N36, etc.

The diameter of N12 is 12 mm.

pile, pile cap

grade beam

footing, column, beam