Accelerating Additives · 🇭🇺 Hungary
Denka SC-1®
Extremely fast – laboratory tests recommendedSetting and hardening accelerator made of amorphous calcium aluminate and anhydrite
Denka SC-1® is a powdered setting and hardening accelerator by the Japanese manufacturer Denka, consisting of amorphous calcium aluminate (ACA) and anhydrite. Dosed at 5–20 % by weight of cement, it accelerates setting and early strength of repair, grouting and water-stop mortars, rapid-setting tile adhesives, flooring compounds and dry-mix shotcrete. As the product sets extremely fast, the working time is adjusted with a suitable retarder. NEWCHEM supplies Denka SC-1® in Hungary and across Europe.
- Composition
- Amorphous calcium aluminate (ACA) + anhydrite
- Dosage
- 5–20 % by weight of cement
- Fineness
- 5,000–7,000 cm²/g (Blaine)
- Packaging
- 20 kg bag · 1,000 kg big bag
Important processing note
Denka SC-1® sets extremely fast. For practicable setting times, a suitable retarder at a somewhat higher than usual dosage is recommended. Laboratory tests are strongly recommended.
Recommended retarder: DENKA SETTER D-200
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Applications
Repair mortars
Rapid repair systems for concrete and screed repair with short reloading times.
Grouts
Rapid-hardening grouting and anchoring mortars, machine foundations, installation mortars.
Water-stop mortars
Sealing systems for stopping pressurised and non-pressurised water.
Tile adhesives
Rapid-setting tile adhesives with early walkability and early grouting.
Flooring compounds
Rapid screeds, levelling and smoothing compounds with fast readiness for floor coverings.
Dry-mix shotcrete
Added as a powder to the dry mix for fast stiffening and high early strength, e.g. for ground support, repair and sprayed mortar work.
The properties depend largely on the ratio of Denka SC-1® to Portland cement, the mix design and the retarder system. We recommend laboratory tests – our technical service team will support you with dosage and retarder adjustment. For shotcrete, dosage, retarder, cement type and machine technology must be adjusted in suitability tests on the project.
Benefits
- Fast to very fast setting: specifically adjustable via the dosage
- High to very high early strength: after only a short time
- Low shrinkage: ettringite formation acts as chemical prestressing
- Stable microstructure without strength loss: no conversion, unlike conventional calcium aluminate cements
- Good adhesion: on cementitious substrates
- Easy handling: easily dosable and conveyable powder, compatible with Portland cements, GGBS, fly ash and hydrated lime
- Shorter closure and waiting times: thanks to very short setting and hardening times
- Suitable for the dry-mix process: can be dosed as a powder directly into the dry mix
Mode of action
Dissolution: ACA and anhydrite dissolve very quickly when water is added.
Ettringite formation: The reaction with water leads immediately to the formation of stable ettringite.
Early strength: Rapid build-up of the microstructure with high early strength and lasting stability.
Control: Suitable retarders set the required working interval.
Microstructural stability: The ettringite formed is a stable compound. Phase transitions (conversion), which can lead to a subsequent loss of strength, do not occur.
Shrinkage behaviour: With sufficient water supply, ettringite formation causes an increase in volume. This acts as chemical prestressing and results in reduced shrinkage on drying.
Control via dosage and retarder
| Property | With increasing dosage |
|---|---|
| Setting time | shorter |
| Early strength | higher |
| Retarder demand | higher |
| Working time | shorter |
Qualitative representation without measured values. Overdosing results in extremely fast setting and very high early strengths. The exact dosage and the optimum ratio of retarder to accelerator must be determined in laboratory tests.
Technical data
Chemical composition (wt.-%, approx.)
| Component | Unit | Specification |
|---|---|---|
| Al₂O₃ | wt.-% | 22–25 |
| CaO | wt.-% | 39–45 |
| SO₃ | wt.-% | 26–30 |
Mineralogical basis: amorphous clinker (amorphous calcium aluminate, ACA) combined with anhydrite.
Physical properties (approx.)
| Property | Unit | Typical value |
|---|---|---|
| Appearance | – | Greyish-white powder, easily dosable and conveyable |
| Particle density | g/cm³ | 2.9–3.1 |
| Fineness according to Blaine | cm²/g | 5,000–7,000 |
| Dosage | % by weight of cement | 5–20 |
| Compatibility | – | Portland cement, ground granulated blast-furnace slag (GGBS), fly ash, hydrated lime |
Typical production values, not guaranteed properties. The current technical data sheet (TDS-DENKA-SC-1-2026-DE, version 1.0, September 2026) is binding.
Standards, quality and safety
Product classification
Denka SC-1® is a functional additive for cement-bound systems. There is no separate CE marking as a construction product. Conformity is demonstrated via the end product (concrete, mortar, dry mortar system).
Application reference
In particular, EN 206 (concrete), EN 197 (cement) and EN 998 (mortar), the requirements for admixtures according to EN 934-2 (to be checked for the specific application) and the national application rules must be observed. For shotcrete, EN 14487 and, for shotcrete admixtures, EN 934-5 also apply; the requirements must be checked for the specific application.
Quality assurance
Batch-related quality testing (chemical composition, fineness, reactivity). Batch-related certificates of analysis on request.
Safety note
Reacts alkaline with water and must be handled like cement. Avoid contact with eyes and skin, wear safety goggles and gloves. Further information in the safety data sheet.
Packaging and storage
| Packaging unit | Net weight |
|---|---|
| Bag | 20 kg |
| Big bag | 1,000 kg |
| Palletising / containers | on request |
Denka SC-1® is sensitive to moisture and must be stored in a dry and cool place. Keep containers closed, protect from moisture and use up opened containers promptly.
Documentation
The following documents for Denka SC-1® are available on request:
- Technical data sheet (TDS-DENKA-SC-1-2026-DE, Version 1.0, 09/2026)
- Safety data sheet (SDS)
- Batch-related certificates of analysis on request
Frequently asked questions
What is Denka SC-1®?
Denka SC-1® is a powdered setting and hardening accelerator by Denka made of amorphous calcium aluminate (ACA) and anhydrite. It accelerates setting and early strength of cement-bound systems such as repair, grouting and water-stop mortars, rapid-setting tile adhesives, flooring compounds and dry-mix shotcrete.
What is the typical dosage of Denka SC-1®?
Typically 5–20 % by weight of cement, depending on the desired properties. With increasing dosage, setting and working time become shorter, early strength higher and the retarder demand greater. The exact amount must be determined in laboratory tests.
Why does Denka SC-1® need a retarder?
The amorphous calcium aluminate is very reactive; ettringite formation starts immediately after water is added. A sufficient working interval is only achieved with a suitable retarder, e.g. DENKA SETTER D-200, recommended at a somewhat higher than usual dosage.
Does Denka SC-1® lose strength through conversion?
No. The ettringite formed is stable; phase transitions (conversion), which can lead to a subsequent loss of strength, do not occur.
Does Denka SC-1® reduce shrinkage?
Yes. With sufficient water supply, ettringite formation leads to an increase in volume that acts as chemical prestressing and reduces shrinkage on drying.
Is Denka SC-1® suitable for shotcrete?
Yes, for shotcrete and sprayed mortar in the dry-mix process. Denka SC-1® is added as a powder to the dry mix and provides fast stiffening and high early strength. Dosage and retarder must be determined in suitability tests with the cement and machine technology used. For the wet-mix process, liquid accelerators are usually used.
Which binders is Denka SC-1® compatible with?
With Portland cements and hydraulic binders including ground granulated blast-furnace slag (GGBS), fly ash and hydrated lime.
What is the difference between Denka SC-1® and Denka Beform®?
Both are based on amorphous calcium aluminates. Denka SC-1® additionally contains anhydrite, is dosed at 5–20 % by weight of cement and sets extremely fast – it is particularly suitable for repair, grouting and water-stop mortars, rapid-setting adhesives, flooring compounds and dry-mix shotcrete. Denka Beform® typically replaces 10–25 % of the cement, its handling time can be adjusted with DENKA SETTER D-300 to approx. 20 minutes to 2 hours, and it is also used for precast concrete and shorter mould cycles.
Does Denka SC-1® have CE marking?
No, as a functional additive it has no separate CE marking. Conformity is demonstrated via the end product (concrete, mortar, dry mortar system), e.g. according to EN 206 or EN 998.
In which packaging is Denka SC-1® available and how is it stored?
In 20 kg bags and 1,000 kg big bags; palletising on request. The product is sensitive to moisture, so store it in a dry and cool place and keep containers closed.
Which documents are available?
Technical data sheet, safety data sheet (SDS) and, on request, batch-related certificates of analysis.
Request sample
Have questions or need technical support? We will respond shortly.