Lytag & Lightweight Concrete
Lightweight concrete refers to concrete where the normal aggregate (dense stone) is replaced wholly or partly by lightweight aggregate or synthetic aggregate (for example, the brand Lytag, derived from pulverised fuel ash). The result is a lower density concrete but with strength and durability adequate for many structural, fill or insulation applications. Using lightweight concrete can reduce dead-load on foundations, make handling easier and improve thermal or fire performance.
Technical details
- Typical densities might range from ~1600 kg/m³ down to ~1350 kg/m³ or lower depending on aggregate and mix design, compared with ~2400 kg/m³ for standard concrete
- Strength and durability can still be high; mix design ensures the concrete meets required strength and exposure class
- Because aggregate is lightweight, modulus of elasticity is lower, shrinkage and creep may differ from normal weight concrete; these must be factored into structural design
- Lightweight concretes may be pumpable, finishable, and suitable for load-bearing slabs, walls or infill, depending on specification.
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Typical applications & key benefits
Typical applications
- Structural concrete where reduced self-weight is beneficial (e.g., tall buildings, raft foundations, precast elements)
- Blocks or panels made from lightweight concrete for lighter façade or partition walls
- Fill for voids or blocks where weight reduction is helpful (e.g., roof decks, podium slabs)
- Screeds or toppings where reduced weight is desired (e.g., over existing structure)
- Drainage beds or filter materials where lighter weight helps handling
Key benefits
- Reduced dead-load ? smaller foundations, lighter structure, potential cost savings
- Improved handling and logistics (lighter loads, easier transport)
- Can provide thermal and fire performance benefits (due to lower density, void structure)
- Versatility in application: structural, fill, blocks, screeds
Specification & durability considerations
- Structural design must factor in the differences in modulus of elasticity, shrinkage and creep of lightweight concrete
- Confirm aggregate type, density, strength, exposure class and finish requirement
- For structural use, match strength class (e.g., 20, 25, 30 N/mm²) with exposure, reinforcement, deflection requirements
- Ensure curing, placement, compaction (if needed) are handled appropriately – lightweight aggregate may absorb more water and require different handling
- Verify compatibility with adjacent materials (e.g., connection to normal-weight concrete elements) and differential movement or settlement.
Ordering & delivery advice
Provide: required density (if specified), strength class, area/volume, element geometry (slab, panel, fill), reinforcement or mesh details, placement method (pump or direct), finish requirement, timing for overlay or loading, and whether lightweight aggregate is required (Lytag or equivalent). Also discuss access and logistics (lighter loads may allow smaller trucks, but pumping arrangements may differ).
