Identify which grade of cement is not available in Indian market:
🔢 What Does the "Grade" of Cement Mean?
The grade of Ordinary Portland Cement (OPC) indicates its strength. Specifically, the grade number represents the minimum compressive strength the cement is expected to achieve after 28 days of curing, when tested under standard conditions. The strength is measured in Newtons per square millimeter (N/mm²) or Megapascals (MPa).
For example, a 43-grade cement should have a minimum compressive strength of 43 N/mm² after 28 days. This grading system allows engineers to select the appropriate cement for the required structural strength.
📝 Detailed Analysis of the Options
(b) 33 grade, (c) 43 grade, and (d) 53 grade
These are the three main grades of Ordinary Portland Cement (OPC) that are manufactured and widely available in the Indian market as per the Bureau of Indian Standards (BIS).
- 33 Grade (IS 269): Used for general, non-structural work like plastering and flooring. Its use has declined in favor of higher grades.
- 43 Grade (IS 8112): A very popular general-purpose cement used for plastering, non-load bearing structures, and concrete work.
- 53 Grade (IS 12269): A high-strength cement used for structural concrete work like reinforced concrete structures, bridges, and high-rise buildings.
(a) 23 grade
This is the correct answer. There is no "23 grade" cement specified by the Bureau of Indian Standards or manufactured in India. The lowest standard grade is 33. Therefore, 23 grade is not available in the Indian market.
📊 Standard OPC Grades in India
| Grade | Minimum 28-day Strength (N/mm²) | Common Uses |
|---|---|---|
| 33 Grade | 33 | Plastering, masonry, non-structural work |
| 43 Grade | 43 | General construction, RCC work, precast |
| 53 Grade | 53 | High-strength concrete, pre-stressed concrete, bridges |
| 23 Grade | - | Not a standard grade / Not available |
💡 Study Tips
- Remember the Trio: 33, 43, 53. These are the only three standard grades of OPC in India. Any other number is likely incorrect.
- Grade = Strength: Always associate the grade number directly with the 28-day compressive strength in N/mm².
- Higher Grade, Higher Strength: The concept is straightforward: a higher grade number means a stronger cement, which is used for more demanding structural applications.