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TechnoblockSlab Blocks & Void Formers

Void-forming EPS blocks — rib-and-block and coffer slab infill, and sacrificial void formers under ground beams on heaving clay.

Kit complete

Technoblock Slab Blocks & Void Formers
Technical documentation

The Technoblock Slab Blocks & Void Formers kit

Brochure, design guide, engineering specification, CAD details and an interactive calculator.

PDF
Product brochureOne-page overview, key specifications, applications.
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PDF
Technical design guideFull design guidance, worked examples, standards references.
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Engineering specificationClause-referenced specification text for your tender documents.
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DWG
CAD detailsEditable construction details, SVG.
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APP
Interactive calculatorSize the system and check performance in your browser.
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PDF
Void-former design guideSacrificial void formers over heaving clay.
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Void-former engineering specificationClause-referenced spec text.
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At a glance

Key specifications

Technoblock is a moulded flame-retardant EPS permanent shutter (lost formwork) and void former laid between concrete ribs/lintels in one-way rib-and-block suspended slabs; the structural concrete topping is cast over and between the blocks, leaving the EPS as permanent lightweight void fill. It is non-structural — all spans, reinforcement and topping are designed by the project engineer.

PropertyValueStandard
Product type / structural roleNon-structural moulded EPS permanent shutter (lost formwork) & void former for one-way rib-and-block suspended concrete slabs
Fire-resistance rating (REI / rated minutes)None — reaction-to-fire classification only; EPS is fully encased in structural concrete in the finished slab
Block sizes (L × W × H)#120: 550 × 320 × 120 (solid); #190: 550 × 320 × 190 (three longitudinal Ø80 cores) mm
Packaging / bundleTB120 — 30 blocks/bundle (1630×730×550); TB190 — 20 blocks/bundle (1670×780×550) mm
Typical #190 slab build-up255 total = 190 block + 65 concrete topping; rib pitch 660 (500 block face + 160 rib); 2 × Y12 per rib; REF 193 mesh in topping mm
Applicable standards / certificationSANS 53501-1 (EN 13501-1) reaction-to-fire; no Agrément or product certificate covers Technoblock (Agrément SA 2020/609 applies to LiteCore only)SANS 53501-1
Product / build-upCustom-cut fire-retardant EPS (expanded polystyrene) blocks & sheets, LiteCel/FRCel range, cut to project size; cast into slabs as lightweight void formers
EPS grades / nominal densitySix grades — 12SD, 15SD, 16DV, 20DV (HD), 24DV, 30DV (EHD); nominal density 12–30 kg/m³
Thermal conductivity (λ, max @ 10 °C)0.033–0.045 W/m·K
Compressive stress @ 10% deformation (min)60–200 kPa
Safe working load @ 1% nominal compression (min)15–100 kPa
Reaction to fireClass B — B-s1,d0SANS 53501-1
DimensionsCut-to-order blocks; raw stock widths 1200 & 1220, thickness 5–600, lengths to 7500 mm

Grade-dependent: the λ (0.033–0.045 W/m·K), density and compressive-stress figures are the general Technopol EPS grade table (grades 12SD–30DV, densities 12–30 kg/m³). The moulded Technoblock's own grade/density is not published — it is specified to the structural design. No Technoblock-specific λ, R- or U-value exists. Reaction-to-fire B-s1,d0 is from Ignis Testing report no. 2023-08-17 Technopol (tested 04 Aug 2023, authorised 17 Aug 2023 by DJ Streicher Pr Eng 880107), performed on a 60 mm generic Technopol FR-EPS sheet at ±18.37 kg/m³ — not on a moulded Technoblock. The report is a material classification, valid 5 years from issue, and does not apply to any specific block or assembly not tested as such. Technoblock is non-structural lost formwork; the compressive-stress row describes the EPS material only, not a slab load rating. Spans, topping, rib reinforcement and propping are designed by the project structural engineer. The #190 slab build-up (255 mm depth, 65 mm topping, 660 mm rib pitch, 2 × Y12, REF 193 mesh) is a single typical CAD detail (190MM Technoblock.pdf), not a published span/design chart. Installed as a rib-and-block system: pre-stressed concrete lintels (ribs) span between supports and the Technoblocks seat between them — the notch (key) along the block underside locates onto the top of the pre-stressed lintel. Density, λ, compressive stress and safe working load are grade-dependent — the range spans the six EPS grades from 12SD (lightest) to 30DV/EHD (densest); select per the specified grade. Per-grade values: λ 0.033/0.034/0.035/0.038/0.040/0.045; compressive @10% 200/160/110/80/65/60 kPa; safe working @1% 100/70/45/21/17/15 kPa (30DV/24DV/20DV/16DV/15SD/12SD). Reaction-to-fire Class B (B-s1,d0) was tested on a 60 mm fire-retardant EPS sheet at ±18.37 kg/m³ to SANS 53501-1 (Ignis Test Laboratory, Cape Town; report no. 2023-08-17 Technopol; authorised 17 Aug 2023, valid 5 years). The company profile additionally cites a B1 rating to SANS 10177-11 at <120 mm. This is a reaction-to-fire classification only — not a fire-resistance (REI) rating. Service temperature: stable to 80 °C long-term / 100 °C short-term (all grades). Technoblock and &lsquo;EPS void formers&rsquo; are the same product: a moulded EPS block used either as rib-and-block / coffer-slab infill, or as a sacrificial void former under ground beams on heaving clay. The two were listed separately in earlier documentation; they are now one line.

Values from Technopol technical documentation. Confirm the exact figures for your specification with Technopol.

Applications

Where this product is used

The same product does a different job in each of these assemblies — each page states the target, the clause and the limits.

Under-Slab & Slab-Edge InsulationGeofoam Lightweight Civil Fill

Every number, its source

Performance data & provenance

Each figure is labelled with how we know it — a named in-validity test, a supplier value, an in-house calculation, or a test whose validity has expired.

PropertyValueStandardSource reportStatus
Nominal density (six grades)12–30 kg/m³Provisional
Thermal conductivity λ @10°C0.033–0.045 W/m·KProvisional
Compressive stress @10%60–200 kPaProvisional
Safe working load @1% compression15–100 kPaProvisional
Reaction to fireB-s1,d0SANS 53501-1IT 23-08-00009Verified
Thermal conductivity λ (grade table)0.033–0.045 W/m·KProvisional
Block sizes (L×W×H)#120: 550×320×120; #190: 550×320×190 mmProvisional
Reaction-to-fire classB-s1,d0SANS 53501-1IT 23-08-00009Verified
Typical #190 slab build-up255 total = 190 block + 65 topping (CAD detail) mmProvisional

Labels are defined on our data promise; every source report is on the test-report register.

The limits

Where not to use this

A material specified for the wrong job fails you, then us. We would rather lose the order.

Void formers left permanently exposed in the finished structure — an EPS soffit in a plant room, a service void, or a stripped-formwork slab where the EPS is never encased or plastered.
EPS is combustible (fire-retardant treated) and carries only a reaction-to-fire class B-s1,d0 (VERIFIED — IT 23-08-00009); it has NO fire-resistance rating, and in a slab the rating comes from the concrete cover, not the EPS.
→ Encase or plaster the soffit, or fit a rated ceiling below it; where the void former must remain exposed in a fire-compartmented space, use a non-combustible permanent formwork.
Formers used as a working platform — trades walking on them, props or back-props landing on them, or bricks/reinforcement stacked on them before the topping is cast.
The safe working load at 1% compression is only 15–100 kPa depending on grade (PROVISIONAL), so a boot heel, a prop head or a stacked pallet is a point load that punches straight through.
→ Lay temporary decking or scaffold planks spanning between the ribs, land all props on the ribs/permanent works, and specify a higher-density grade if the former must be trafficked at all.
Formers placed in wet concrete without hold-downs, or on a job using a solvent-based release agent, curing compound or bonding primer.
EPS is buoyant and will float out of the pour if not restrained, and solvent-based release agents and curing compounds attack and pit the EPS on contact.
→ Mechanical hold-downs/tie-wires to the reinforcement, and water-based release agents and curing compounds only — check the chemical compatibility of every product touching the EPS before the pour.
Anyone treating the block as structural — assuming it carries load, sets the rib span, or contributes to the slab's capacity.
Technoblock is a NON-structural moulded EPS permanent shutter (lost formwork) and void former; every span, rib, reinforcement bar and topping thickness is the project engineer's design, and the block carries nothing in the finished slab.
→ An engineer-designed rib-and-block slab (typical #190 build-up: 190 block + 65 topping = 255 mm, PROVISIONAL) — and where the infill block must contribute structurally, use concrete or clay infill blocks instead.
A slab soffit left with the EPS exposed and unplastered in an occupied or fire-compartmented space.
The block has NO fire-resistance rating — only a reaction-to-fire class B-s1,d0 (VERIFIED — IT 23-08-00009); the slab's fire rating comes from the concrete cover to the ribs, so exposed EPS between the ribs sits outside the rated envelope and is a combustible ceiling surface.
→ Plaster or encase the soffit, or fit a rated suspended ceiling; use concrete or clay infill blocks where the soffit must remain exposed.
Slabs where trades walk on the blocks, back-props land on them, or reinforcement and bricks are stacked on them before the topping is cast.
A 550 × 320 mm EPS block spanning between ribs will punch through under a point load — it has no capacity for construction traffic and no edge bearing to speak of.
→ Temporary planks or decking spanning rib-to-rib for all access, all props landing on the ribs or permanent works, and a pre-pour walk-through to check for punctures.
Where it has been used

Project references

No project on the public register is tagged to this application yet. Ask us for references — we will send the ones that match your building type.

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Technical resource

Who should we send this to?

We release technical documentation to named engineers and specifiers so we can support you properly on the project. One entry unlocks everything.

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