In structural concrete and pavement engineering, not all crushed stone is created equal. The physical shape and mechanical strength of aggregate particles play a decisive role in determining compressive strength, workability, and cement consumption.
1. Flakiness Index & Elongation Index
Flaky particles (thickness less than 0.6 times mean dimension) and elongated particles (length greater than 1.8 times mean dimension) create voids in concrete mixes. High flakiness leads to:
- Higher cement paste requirement to coat flat surfaces
- Lower compressive and flexural strength
- Increased risk of particle breakage during compaction
At MERL, our multi-stage cone crushing circuits ensure a cubical particle shape with a Flakiness Index strictly below 12%.
2. Aggregate Impact Value (AIV)
AIV measures the resistance of aggregate to sudden shock or impact. For high-load highway wearing courses and railway ballast, MoRTH specifies AIV values below 18-20%. MERL quarry sites feature high-density granite gneiss rock delivering exceptional impact resistance.
3. Water Absorption & Soundness
Low water absorption (< 0.5%) prevents freeze-thaw degradation and prevents absorption of mixing water from fresh concrete mixes, ensuring predictable slump and strength development.