As per IS 3812 (Part 1): 2013, which type of ash is prepared from fly ash or bottom ash or both, conveyed and deposited in dry form?
Correct Answer: A. Mound ash
📚 Detailed Explanation: Mound Ash — IS 3812 (Part 1): 2013 Classification
Why A (Mound ash) is correct: IS 3812 (Part 1): 2013 classifies ash generated from pulverised coal combustion. The key distinguishing characteristic of mound ash is that it is prepared from fly ash, bottom ash, or a combination of both — and critically, it is conveyed and deposited in the dry state. This is what differentiates it from pond ash, which is handled in slurry (wet) form.
IS 3812 (Part 1): 2013 Classification of Fly Ash Products
| Ash Type | IS 3812 Definition | Transport State | Deposition State | Primary Use |
|---|---|---|---|---|
| Mound ash | From fly ash, bottom ash, or both in any proportion | Dry (pneumatic or mechanical conveying) | Dry | Engineered fill; land reclamation |
| Pond ash | From fly ash, bottom ash, or both in any proportion | Wet (slurry/hydraulic) | Wet (settled from slurry in ash pond) | Controlled fill; bricks; road sub-base |
| Fly ash (Class F/C) | Fine ash captured from flue gas by precipitators | Dry or slurry | Dry storage silos or ponds | SCM in concrete; PPC; geopolymer |
Why Other Options Are Wrong
| Option | What It Is | Why Wrong Here |
|---|---|---|
| A. Mound ash | Dry-deposited ash from fly/bottom ash | Correct answer |
| B. Pulverized fuel ash | General term for all ash from burning pulverised coal; not specifically the dry-deposited type defined here | Too broad; not the specific IS 3812 definition asked |
| C. Calcareous fly ash | High-calcium fly ash (Class C, >20% CaO); self-cementitious; more common in North American classification (ASTM C618) | Not the term used in IS 3812 Part 1: 2013 |
| D. Pond ash | Ash transported in slurry and settled in ash ponds (wet deposition) | Opposite to the dry deposition described in the question |
- Mound ash (IS 3812 Part 1: 2013) = fly ash + bottom ash (any proportion) conveyed and deposited dry.
- Pond ash = same source materials but transported in slurry and deposited wet in ash ponds.
- The critical distinction is the dry state of transport and deposition for mound ash.