Updated: Nov 14, 2021
The strength of the concrete is termed by grade. The grade reflects the compressive strength which is the characteristic strength of concrete after 28 days. It is depicted by a letter M followed by a number. For instance, if the grade of the concrete is said to be M20, it means that the concrete mix (M) has a compressive strength of 20 N/mm2. Various grades of concrete are used for different applications in home constructions.
Different types of concrete including ordinary, standard and high strength concrete include use of various grades. Ordinary concrete includes grades of M10, M15 and M20. The standard ones include M25, M30, M35, M40, M45, M50, and M55. The high strength concrete includes M60 and M80 grades.
Generally M10 and M15 grades of concrete are used for leveling course, and bedding for footings. Standard concrete and concrete of grade M20 is applicable for Reinforced Cement Concrete (RCC) works for slabs, beams, columns and so on. The high strength concrete has its applications for high rise buildings.
The proportion of the materials in the concrete mix also varies for different applications. For instance, a proportion of 1 : 2 : 4 (M15) consists of (1 part of cement, 2 parts of sand, and 4 parts of aggregates) and proportion of 1 : 1.5 : 3 (M20) consists of (1 part of cement, 1.5 parts of sand, and 3 parts of aggregates)
The quantity of water required per bag of cement (50 kg) is about 25 liters.