Classification of Aggregates

Classification of Aggregates

Key Concepts

1. Definition of Aggregates

   • Aggregates comprise sand, gravel, crushed stone, and recycled concrete.
   • They are used in construction to provide bulk, strength, and wear resistance.

2. Types of Aggregates

   • Natural Aggregates:
     • Derived from natural sources like riverbeds, quarries, and pits.
     • Examples: Sand, gravel.
   • Processed Aggregates:
     • Manufactured from natural stone or by recycling materials.
     • Examples: Crushed stone, recycled concrete.

3. Classification Criteria

   • Size:
     • Fine Aggregates: Particles smaller than 4.75 mm.
     • Coarse Aggregates: Particles larger than 4.75 mm.
   • Source:
     • Natural Aggregates: Directly obtained from the environment.
     • Artificial Aggregates: Produced using by-products or synthetic materials.
   • Density:
     • Lightweight Aggregates: Density less than 1120 kg/m³.
     • Normal Weight Aggregates: Density between 1520-1680 kg/m³.
     • Heavyweight Aggregates: Density greater than 2080 kg/m³.
   • Shape:
     • Rounded, angular, flaky, and elongated.

4. Properties

   • Physical: Affect durability and stability of the structure.
     • Examples include shape, size, texture, and volume.
   • Mechanical: Influence the strength and load-bearing capacity.
     • Strength, abrasion resistance.
   • Chemical: Determine compatibility with cement and effects on concrete.
     • Reactivity, impurities.

5. Uses in Construction

   • Concrete Production: Essential for forming concrete mixes.
   • Road Construction: Used as base material for pavements.
   • Landscaping: Decorative aggregates for aesthetic purposes.
   • Drainage Systems: Used to create permeable layers for water filtration.

6. Environmental Considerations

   • Recycling aggregates help in reducing environmental impact.
   • Sustainable sourcing practices are important for preserving natural resources.

These points provide a comprehensive summary of the primary concepts related to the classification of aggregates, based on the provided text.