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Concrete is a construction material composed of cement, fine aggregate (sand) and coarse aggregate mixed with water. It is a material that starts setting and gradually with increased bonding becomes hard like stone.
Its importance is key because it contributes extensively in buildings, bridges and most infrastructural projects. The material is of immense value even though it is a man-made material on earth.
During INFRACON, 2017 in India with theme “the Innovations in Concrete for Infrastructure Challenges”; Concrete was recognized as one of the essential components of infrastructure development in the nation.
GRADE OF CONCRETE
Grade of concrete is like the concrete strength required for construction. Some of us know that the strength of concrete is measured by testing sample cubes at 7 and 28 days. But to pour the concrete into structure, a structural designer must first approve the right concrete mix for its characteristic properties.
The grade of concrete is usually mentioned as M15, M20, M25, M30, M40 etc. The M stands for a Mix of concrete and the number stands for minimum compressive strength requirement at 28 days after mixing and placing of concrete.
For example M30 grade signifies that compressive strength required for construction is 30 Mega Pascal (MPa). Meaning “M” is the mix and 30 is the required strength in MPa. Meanwhile according to various lab tests, grade of concrete is presented in Mixed Proportions.
Reinforced Concrete construction has a minimum of M20 While for plain cement concrete works M15 is generally used. Civil Engineers at site measures concrete strength with a cube or a cylinder. This cube or cylinders are made during casting of structural member and after hardening it is cured for 28 days.
WHY IT IS IMPORTANT FOR STRUCTURES
Concrete grade is vital because it ensures the efficiency of the structures. It also helps in getting the best strength for any structure to avoid future collapse.
The grade of concrete also helps Civil Engineers to save cost as the right strength will prevent more lab test. This is because the lowest grade of concrete means bigger element sizes which means more quantities of concrete. While on the other hand more strength of concrete means less sizes of elements which means less concrete quantities.