What is Concrete Grade ?

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is designated based on its at 28 days as measured in standard conditions with a 150 mm size cube. According to IS 456-2000, concrete is graded into three types.

Ordinary Grade
Standard Grade
High strength Concrete
Grade of concrete construction is selected based on structural design requirements. There are two types of concrete mixes, nominal mix and design mix. Nominal mix concrete are those which are generally used for small scale construction and small residential buildings where concrete consumption is not high. Nominal mix takes care of factor of safety against various quality control problems generally occurring during concrete construction. Design mix concrete are those for which mix proportions are obtained from various lab tests. Use of design mix concrete requires good quality control during material selection, mixing, transportation and placement of concrete. This concrete offers mix proportions based on locally available material and offers economy in construction if large scale concrete construction is carried out. Thus, large concrete construction projects uses design mix concrete. So, suitable grade of concrete can be selected based on structural requirements. Nominal mixes for grades of concrete such as M15, M20, M25 are generally used for small scale construction. Large structures have high strength requirements, thus they go for higher grades of concrete such as M30 and above. The mix proportions of these concretes are based on mix design.

Sample Solution

  • Concrete Grade: The grade of concrete is designated based on its compressive strength at 28 days, measured in standard conditions with a 150 mm size cube.
  • Concrete Types: IS 456-2000 classifies concrete into three types: Ordinary Grade, Standard Grade, and High Strength Concrete.
  • Concrete Mixes: There are two types of concrete mixes: nominal mix and design mix.
    • Nominal Mix: Used for small-scale construction and small residential buildings. Proportions are predetermined and take into account potential quality control issues.
    • Design Mix: Proportions are determined through laboratory testing and require better quality control during material selection, mixing, transportation, and placement.
  • Concrete Grade Selection: The grade of concrete is selected based on structural design requirements. Nominal mixes like M15, M20, and M25 are suitable for small-scale construction, while larger structures require higher grades like M30 and above.
  • Mix Design: Design mix concrete offers tailored proportions based on locally available materials and can be more economical for large-scale construction projects.

Additional points:

  • Factors affecting concrete strength: Besides the grade, other factors like curing, water-cement ratio, and aggregate quality can influence concrete strength.
  • Special concretes: There are also special concretes with specific properties, such as lightweight concrete, high-performance concrete, and fiber-reinforced concrete.
  • Code compliance: It’s essential to follow the guidelines of IS 456-2000 or other relevant building codes when selecting and using concrete for construction projects.

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