IS Code for Aggregate in Construction

In India, the IS Code (Indian Standard) for aggregates used in construction is IS 383: 2016 – Specification for Coarse and Fine Aggregates from Natural Sources for Concrete. This code outlines the requirements for the quality of aggregates that are used in the production of concrete for all types of construction projects.

Key Points from IS 383: 2016

1. Types of Aggregates:

   • Aggregates are classified into two major categories:
     • Coarse Aggregate: Particles greater than 4.75 mm in size.
     • Fine Aggregate: Particles that are smaller than 4.75 mm in size.

2. Source of Aggregates:

   • The aggregates should be sourced from natural sources like riverbeds, quarries, or mines. In some cases, artificial aggregates are used, which should meet specific requirements.

3. Grading of Aggregates:

   • The aggregates are classified into different gradation categories based on the particle size distribution. Grading is important as it influences the strength, workability, and durability of concrete.
   • There are different grading zones for fine aggregates (I, II, III, IV) depending on the fineness modulus.

4. Strength Requirements:

   • Aggregates should have a high compressive strength, as they play a crucial role in the overall strength of the concrete.

5. Physical Properties:

   • The specific gravity, bulk density, water absorption, and abrasion resistance of the aggregates are critical for ensuring the long-term durability of the concrete.
   • The moisture content in aggregates should also be considered, as excess moisture can affect the mix design and workability of concrete.

6. Size of Aggregates:

   • Coarse aggregates should be between 5 mm to 80 mm in size for normal concrete. Fine aggregates should pass through a 4.75 mm sieve and retain on a 0.075 mm sieve.
   • Particle shape: Angular, rounded, or flaky particles are to be avoided, as these affect the workability and strength of concrete.

7. Soundness:

   • The aggregates should be durable and resistant to weathering and chemical action. This is typically tested using a soundness test where aggregates are subjected to a wetting and drying cycle.

8. Impurities in Aggregates:

   • Aggregates should be free from harmful materials such as clay, silt, organic matter, dust, or other foreign substances that can adversely affect the performance of concrete.

Other Related IS Codes

1. IS 2386 (Part 1 to 8): 1963 - Methods of Test for Aggregate for Concrete:

   • This set of standards provides the testing procedures for various physical properties of aggregates, such as specific gravity, abrasion resistance, water absorption, and fineness modulus.

2. IS 1124: 1974 - Method of Test for Determining the Durability of Coarse Aggregates:

   • It specifies the test methods for determining the durability of coarse aggregates used in concrete, including tests for soundness, freeze-thaw resistance, and weathering.

3. IS 383: 2016 (Reaffirmed) – This is the latest standard for aggregates used in concrete.

Conclusion

The IS 383: 2016 is the primary Indian Standard (IS Code) for aggregates used in construction, particularly in the making of concrete. This standard helps ensure the aggregates meet the necessary quality and durability requirements for producing high-strength, long-lasting concrete. Understanding and following these standards ensures the structural integrity and performance of the final concrete structure.

Sun Jan 26, 2025