What is k-400 grade of concrete?

K-400 grade concrete refers to a specific classification of concrete that can withstand a compressive strength of 400 kg/cm² (or approximately 40 MPa) when fully cured. This grade is commonly used in structural applications like beams, columns, and slabs due to its high strength and durability. The "K" typically indicates a standard grading system used in some regions, particularly in Asia.