Crushed stones are a fundamental material used in highway construction due to their durability, strength, and ability to provide proper drainage. Here’s an overview of their role and types:
1. Uses of Crushed Stones in Highways
– Base & Subbase Layers: Provide load-bearing support and distribute traffic loads.
– Surface Course (Asphalt or Concrete Mix): Used as aggregates in asphalt pavement or Portland cement concrete.
– Drainage Layers: Facilitate water runoff to prevent waterlogging.
– Shoulder & Embankment Stabilization: Reinforce roadside areas.
2. Types of Crushed Stones Used
Different types of crushed stones are selected based on hardness, gradation, and abrasion resistance:
– Granite: Hard, durable, ideal for high-traffic roads.
– Limestone: Cost-effective but less resistant to heavy loads.
– Trap Rock (Basalt): High strength, excellent for wear resistance.
– Sandstone & Gravel: Used in lower layers due to lower strength.
3. Key Properties for Highway Construction
– Gradation (Particle Size Distribution): Must meet specifications (e.g., ASTM D448).
– Los Angeles Abrasion Test (LAA): Measures resistance to wear (80% for base layers).
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4. Advantages of Crushed Stones
– High load-bearing capacity.
– Permeability pr.jpg)
nts water retention.
– Cost-effective compared to other materials.
5. Challenges
– Dust generation during production/placement.
– Requires proper compaction to avoid settlement issues.
Would you like details on specific standards or testing methods?