Structural Innovation
Voided
Slab
Voided slab is an advanced structural system that utilizes internal voids to reduce slab weight — enabling longer spans with higher efficiency, without the need for additional columns.
Our Core Systems
Specialized voided slab systems designed for different project needs and structural requirements.
Foermli
Formli is an advanced voided slab system based on Swiss technology, engineered to enhance structural efficiency by reducing weight and material usage — without compromising performance.
- Lighter slabs with high structural performance
- Longer spans with greater design flexibility
- Significant reduction in concrete and steel usage
- Suitable for large-scale and complex project requirements
DMAX
DMAX is an advanced voided slab system engineered to improve structural efficiency by reducing concrete consumption and accelerating construction — while maintaining high performance and reliability.
- Reduced concrete volume within the slab
- Faster execution with improved site organization
- Enhanced structural performance with reduced building weight
- Longer spans achieved with greater efficiency
Plastic Formwork Systems
MaxSpan offers advanced plastic formwork systems as a practical alternative to traditional formwork — designed to accelerate construction, reduce waste, and maintain high-quality finishes.
- High reusability
- Fast assembly and dismantling
- Accurate dimensions with consistent results
- Reduced waste and better site organization
WHY SWITCH?
Comparison with Traditional Systems
Voided slab systems are designed to reduce weight and material consumption through internal voids — delivering higher structural efficiency compared to conventional solid slabs.
Traditional Solid Slab
- Heavier concrete weight increases structural loads
- Limited spans requiring additional columns
- Higher material consumption and carbon footprint
- Longer construction timelines
- Limited design flexibility
Voided Slab Systems
- Up to 35% reduction in weight compared to solid slabs
- Spans up to 20 meters without intermediate columns
- Up to 30% reduction in material usage and carbon emissions
- Faster execution and improved site efficiency
- Greater design flexibility with larger open spaces
CASE STUDY · DMAX
DMAX Structural & Material Performance
A direct comparison between a conventional solid slab and a DMAX voided slab on the same 8 m × 8 m column grid, covering concrete volume, deflection and reinforcement demand under identical loading.
23.4%
Concrete volume saving
15%
Reinforcement saving
0.91
Stiffness factor
32 mm
Deflection, matched to solid slab
CASE STUDY · 01
Model Setup & Concrete Volume
Both slabs are modelled on the same 8 m center-to-center span with 50 × 50 cm columns and identical live and superimposed dead loads, isolating the effect of the DMAX void formers on material consumption.
SPAN LENGTH
8 m center-to-center
COLUMNS
50 × 50 cm
LIVE LOAD (LL)
2.5 kN/m²
SUPERIMPOSED DEAD LOAD
4.5 kN/m²
Traditional Solid Slab
Uniform 35 cm solid slab across the complete structural bay.
Slab thickness: 35 cm
Concrete volume: 25.3 m³
DMAX Voided Slab
A 32 cm DMAX slab with void formers reducing self-weight over the same bay.
Slab thickness: 32 cm
Void volume: 3.75 m³
Dead-load reduction: 2.0 kN/m²
Concrete volume: 19.4 m³
−23.4%
Concrete volume is reduced from 25.3 m³ to 19.4 m³. The DMAX slab is also 3 cm thinner, while retaining a stiffness factor of 0.91 relative to the solid section.
SYSTEM DETAIL
The Single-Unit Module
Each void former is a sealed corrugated unit arranged on a fixed 160 mm module between the top and bottom reinforcement mats.
- Locking clips keep the units closed during casting and prevent concrete from entering the void.
- Integrated top and bottom spacers establish reinforcement cover.
- The corrugated geometry improves local stiffness under wet-concrete pressure.
CASE STUDY · 02
Deflection Performance
Finite-element deflection contours for both slabs under the same load case, checked against the allowable span/240 deflection limit.
Solid Slab · 35 cm
Maximum deflection: 32 mm
Allowable deflection (L/240): 33 mm
DMAX Slab · 32 cm
Maximum deflection: 32 mm
Allowable deflection (L/240): 33 mm
32 mm
The DMAX slab matches the solid slab’s peak deflection and remains within the 33 mm allowable limit, despite being 3 cm thinner and using 23.4% less concrete.
CASE STUDY · 03
Reinforcement Demand
Required reinforcement demand for both systems, taken from the same design strips along grid lines A–B and 1–2.
Traditional Solid Slab
Moment and reinforcement demand across the solid slab section.
DMAX Voided Slab
Lower reinforcement demand resulting from the reduced self-weight of the voided section.
−15%
Overall reinforcement demand is reduced by 15% in the DMAX slab as a direct result of the lighter structural self-weight.
TECHNICAL SUMMARY
Solid Slab vs. DMAX Slab
The principal material and structural results from the identical design bay and loading conditions.
| Metric | Solid slab | DMAX slab | Change |
|---|---|---|---|
| Slab thickness | 35 cm | 32 cm | −3 cm |
| Concrete volume | 25.3 m³ | 19.4 m³ | −23.4% |
| Void volume | — | 3.75 m³ | — |
| Dead-load reduction in voided area | — | 2.0 kN/m² | Added benefit |
| Stiffness factor | 1.0 reference | 0.91 | −9% |
| Maximum deflection | 32 mm | 32 mm | Matched |
| Allowable deflection (L/240) | 33 mm | 33 mm | — |
| Reinforcement demand | Baseline | −15% | −15% |
Source: DMAX Voided Slab System Catalog, case study pages 12–14. Load case: LL 2.5 kN/m², SDL 4.5 kN/m², 8 m × 8 m grid and 50 × 50 cm columns.
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