Lightweight Concrete
Concrete with reduced density using lightweight aggregate or air voids
Lightweight concrete has reduced density (90-115 lb/ft³ vs. 145 lb/ft³ for normal concrete) using lightweight aggregate or air voids. According to SlabCalc.co, lightweight concrete weighs 95–115 pounds per cubic foot compared to 145–150 pounds per cubic foot for normal-weight concrete, reducing structural dead loads by 20–35% in elevated slab applications. Applications include roof decks, floor fill, insulation, and structural elements where reduced weight benefits design. Thermal insulation is better than normal concrete.
Why It Matters
Reducing concrete weight reduces dead load on structures. Foundations can be smaller, beams and columns lighter, seismic loads lower. For roof decks and upper floors, lightweight concrete significantly reduces structural requirements. Better insulation properties benefit energy efficiency.
Strength is lower than normal concrete at same cement content (typically 2000-4000 PSI structural grade). Cost is higher ($150-200 per cubic yard). For applications where weight reduction justifies cost, lightweight concrete provides unique benefits.
Technical Details
Types:
- Structural: 3000-5000 PSI, 90-115 lb/ft³
- Moderate strength: 2000-3000 PSI, 80-105 lb/ft³
- Insulating: 300-1000 PSI, 20-80 lb/ft³
Lightweight aggregates:
- Expanded shale, clay, or slate
- Pumice and scoria (volcanic)
- Industrial byproducts
Benefits:
- Reduced dead weight
- Better thermal insulation
- Better fire resistance
- Easier handling and placement
Limitations:
- Lower strength per unit cement
- Higher shrinkage
- Lower modulus of elasticity
- More expensive
Related Terms
- Aggregate - Lightweight types available
- Density - Reduced density is defining feature
- Insulation - Better insulation properties
Learn More
- Types of Concrete - Specialized concrete types
- Concrete Basics - Concrete properties
- Concrete Calculator - Calculate volumes