Lightweight Aggregate Block Calculator: Complete Reference
Lightweight Aggregate Concrete Basics
Lightweight aggregate (LWA) concrete uses expanded clay (LECA), expanded shale, pumice, or sintered PFA instead of dense gravel, reducing density to 800–1600 kg/m³ (vs 2400 for dense concrete) while maintaining fc 8–30 MPa. Widely used for mid-rise load-bearing walls, flooring units, and insulating blockwork.
Key LWA types: Expanded clay (Lytag/LECA): 300–700 kg/m³ bulk; Expanded shale: 600–900 kg/m³; Pumice: natural volcanic, 400–700 kg/m³; Sintered PFA: 700–900 kg/m³.
Mix Design
LWA mix density = Σ(ρ_i × V_i). Strength estimated by: fc ≈ (107/w²c) × (ρ_mix/2400)^1.5. Pre-wet LWA 24h before mixing to prevent internal absorption reducing workability. Use 350–450 kg/m³ cement + w/c 0.40–0.50 for structural grades.
Thermal Performance
λ ≈ 0.038 × (ρ/100)^0.62 W/m·K. At 800 kg/m³: λ ≈ 0.21 W/m·K — about 3–5× better than dense concrete. 200mm LWA block wall: U ≈ 0.9 W/m²K. For energy-code compliance, combine with external insulation.
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FAQs
What is LECA block density?
LECA (Lightweight Expanded Clay Aggregate) blocks typically have dry density 700–1100 kg/m³ and fc 6–15 MPa. Compare to dense concrete blocks at 2100–2300 kg/m³.
Can LWA blocks be structural?
Yes. Grade 7.5–20 MPa LWA blocks are used for load-bearing walls in buildings up to 8 storeys. Use fc ≥ 8 MPa and wall thickness ≥ 190mm for multi-storey structural walls.
How does LWA compare to AAC?
LWA blocks: higher strength (8–25 MPa vs 3–6 MPa AAC), higher density (800–1400 vs 400–700 kg/m³ AAC), lower insulation but better structural performance. AAC is better for pure insulation; LWA for structural-insulating balance.