- 2071 Chaitra · 2 marks
Hydraulic and fat lime properties
Short answer
Fat lime (>95% CaO) is white, slakes violently, sets only in air and has low strength. Hydraulic lime (5–30% clay) is greyish, slakes slowly, sets under water and achieves higher strength.
Explain hydraulic lime and fat lime with their properties.
Fat lime
Pure quicklime with over 95% CaO.
- White colour, slakes with great heat and swelling.
- Sets slowly in air by absorbing CO₂, not under water.
- Low strength, high plasticity.
- Used for whitewashing and plaster.
Hydraulic lime
Limestone burnt with 5 to 30% clay.
- Greyish colour, slakes slowly with little heat and expansion.
- Sets under water and in damp places through hydration of silicates and aluminates, and gains good strength.
- Classified as feebly, moderately and eminently hydraulic.
- Used for mortar in foundations, damp places and masonry below ground.
✓ Answer checked by Claude Opus 5.5 (high effort)
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