Determining the particle size distribution of aggregates is known as grading, which is a crucial factor in designing concrete mixes. The grading of aggregates can impact both the strength and durability of concrete, making it an essential consideration in concrete construction. To ensure proper grading, specific limits have been established for different types of aggregates, which are detailed in the following tables. Overall, proper grading of aggregates plays a significant role in achieving optimal concrete construction results.
Grading Limit for Single Sized CoarseAggregates
(Based on Clause 4.1 and 4.2 of IS: 383- 1970)
| IS Sieve | Percentage passing for single sized aggregates of nominal size(mm) | |||||
| 63 mm | 40 mm | 20 mm | 16 mm | 12.5 mm | 10 mm | |
| 80 mm | 100 | – | – | – | – | – |
| 63 mm | 85 – 100 | 100 | – | – | – | – |
| 40 mm | 0 – 30 | 85 – 100 | 100 | – | – | – |
| 20 mm | 0 – 5 | 0 – 20 | 85 – 100 | 100 | – | – |
| 16 mm | – | – | – | 85 – 100 | 100 | – |
| 12.5 mm | – | – | – | – | 85 – 100 | 100 |
| 10 mm | 0 – 5 | 0 – 5 | 0 – 20 | 0 – 30 | 0 – 45 | 85 – 100 |
| 4.75 mm | – | – | 0 – 5 | 0 – 5 | 0 – 10 | 0 – 20 |
| 2.36 mm | – | – | – | – | – | 0 – 5 |
Grading Limits for Fine Aggregates
(Based on Clause 4.3 of IS: 383 – 1970)
| IS Sieve Designation | Percentage Passing | |||
| Grading Zone I | Grading Zone II | Grading Zone III | Grading Zone IV | |
| 10 mm | 100 | 100 | 100 | 100 |
| 4.75 mm | 90 – 100 | 90 – 100 | 90 – 100 | 95 – 100 |
| 2.36 mm | 60 – 95 | 75 – 100 | 85 – 100 | 95 – 100 |
| 1.18 mm | 30 – 70 | 55 – 90 | 75 – 100 | 90 – 100 |
| 600 microns | 15 – 34 | 35 – 59 | 60 – 79 | 80 – 100 |
| 300 microns | 5 – 20 | 8 – 30 | 12 – 40 | 15 – 50 |
| 150 microns | 0 – 10 | 0 – 10 | 0 – 10 | 0 – 15 |