Table of Contents
Introduction to LDA
Low-Density Aggregate (LDA), also known as Lightweight Aggregate (LWA), is a fly ash-based material revolutionizing global construction. With over 95% fly ash composition, LDA replaces natural coarse aggregates (stone chips), offering:
- 20–25% reduction in concrete dead load
- 40% lower aggregate usage vs. natural stone
- Compliance with ASTM C330, BS EN 13055:2002, and IS 9142 Part-2:2018
LDA vs. Natural Aggregate: Key Comparisons
Physical Properties
| Property | LDA | Natural Aggregate |
|---|---|---|
| Bulk Density | 750–900 kg/m³ | 1450–1750 kg/m³ |
| Water Absorption | 12–16% | 0.5–1.5% |
| Specific Gravity | 1.45–1.65 | 2.75–2.95 |
| Concrete Weight | 1600–1900 kg/m³ | 2400–2750 kg/m³ |
| Thermal Conductivity | 0.58 W/m·K | 1.4 W/m·K |
| Cost Savings | Up to 40% | — |
Strength & Durability (per BS EN 13055-1:2002)
- Crushing resistance: >6 MPa
- Impact value: 32–38% (max 40%)
- Abrasion value: 26–35% (max 45%)
Advantages of LDA Concrete
✅ Structural Benefits
- Reduces steel reinforcement needs due to lower dead weight.
- Low shrinkage, minimizing micro-cracks.
- Pumpability: Easier placement vs. traditional concrete.
✅ Sustainability
- 100% fly ash-based (aligned with CII-GBC GreenPro Certification).
- 40% reduction in natural aggregate demand.
- Lower transport emissions (higher volume per load).
✅ Economic Efficiency
- Cheaper than natural aggregates.
- Lower energy costs due to thermal insulation (0.58 W/m·K).
Applications of LDA
- Structural concrete (bridges, high-rises like Burj Khalifa)
- Precast elements (walls, floors, cladding)
- Roofing & waterproofing
- Arrestor beds and masonry work
LDA Mix Design Guidelines *(Per IS 9142 Part-2:2018)*
| Grade | Cement (kg) | Water (kg) | LDA 8–16mm (kg) | LDA 4–8mm (kg) | River Sand (kg) | Density (kg/m³) |
|---|---|---|---|---|---|---|
| M-20 | 313 | 163 | 543 | 136 | 715 | 1870 |
| M-25 | 357 | 175 | 497 | 166 | 677 | 1872 |
| M-30 | 386 | 170 | 502 | 167 | 654 | 1879 |
Note: Adjust for moisture content and ambient conditions.
Environmental Impact
♻ Circular Economy:
- Fly ash recycling reduces landfill waste.
- 3R Compliance: Reduce, Reuse, Recycle.
🌱 Carbon Footprint:
- 50% lower CO₂ vs. natural aggregate production (per UNEP 2022).
Global Standards & Certifications
- India: ISI Mark (IMFA)
- EU: EN 13055:2002
- USA: ASTM C330
- GreenPro Certified (CII-GBC, Hyderabad)
Supplier Spotlight: IMFA (India)
Indian Metals & Ferro Alloys Ltd (IMFA) – Pioneers in LDA production:
- Location: Choudwar, Odisha
- Raw Material: Fly ash from captive thermal power plants
- Contact:
- Mr. Debasis Mahapatra: +91 9777575684
- Mr. Naresh Sahoo: +91 9777440160
Supply Options:
- Loose bulk
- 25kg/500kg bags
Key Takeaways
✔ LDA cuts costs and weight without compromising strength.
✔ Ideal for sustainable projects (LEED/GRIHA compliance).
✔ Always verify supplier certifications (ISI, ASTM, EN).
Next Steps:
📥 Download our free LDA Mix Design Calculator
🔗 Explore case studies: IMFA LDA Projects
