Pick up the correct statement from the following
Correct Answer: D. All option are correct
📚 Detailed Explanation: Types of Sand and Their Characteristics
Fine aggregates are available from several natural and manufactured sources. The two most common types in Indian construction are river sand (natural) and crushed stone sand / manufactured sand (M-sand). Each has distinct particle shape, texture, and suitability characteristics.
Why D (All option are correct) is correct:
Statement A — River sand is naturally obtained from riverbeds and riverbanks; it has been continuously shaped by flowing water over geological time.
Statement B — Crushed stone sand (also called M-sand or artificial sand) is produced by mechanical crushing of quarry rock, typically granite or basalt.
Statement C — This is the key physical distinction: river sand is naturally worn to smooth, rounded particles (good workability, weaker bond); crushed stone sand is angular with rough surfaces (better bond with cement, but needs more water for same workability).
Statement A — River sand is naturally obtained from riverbeds and riverbanks; it has been continuously shaped by flowing water over geological time.
Statement B — Crushed stone sand (also called M-sand or artificial sand) is produced by mechanical crushing of quarry rock, typically granite or basalt.
Statement C — This is the key physical distinction: river sand is naturally worn to smooth, rounded particles (good workability, weaker bond); crushed stone sand is angular with rough surfaces (better bond with cement, but needs more water for same workability).
Comparison: River Sand vs. Crushed Stone Sand
| Property | River Sand | Crushed Stone Sand (M-Sand) |
|---|---|---|
| Shape | Smooth, rounded | Angular, rough |
| Texture | Smooth | Rough / granular |
| Bond with cement | Weaker (smooth surface) | Stronger (rough surface) |
| Water demand | Lower | Higher |
| Environmental impact | High (river mining) | Lower (quarry by-product) |
Key Concepts for Students
- M-sand is increasingly replacing river sand in India due to river sand shortages and environmental regulations.
- M-sand may contain excess fines (crusher dust) that must be washed out to meet IS 383 grading requirements.
- Despite being angular, M-sand concrete can achieve the same workability as river sand concrete with the use of plasticiser admixtures.