MC-Bauchemie MC-Montan Shotcrete HA 02
An alkali-free liquid accelerator dosed at the shotcrete nozzle, built for tunnels, mine drifts and rock faces that need fast, safe set-up without giving away long-term strength.
What is it?
A liquid, alkali-free accelerator (EN 934-5, Type T2) metered into sprayed concrete at the nozzle for rapid, controllable hardening.
Where is it used?
Tunnel primary support (NATM/SEM), mine drift and gallery linings, rock-face and hillside stabilisation, and any wet- or dry-mix shotcrete job needing a thick single-pass layer.
Why use it?
High early strength with a comparatively small hit to final compressive strength, less rebound and dust at the nozzle, and gentler on skin and eyes than the sodium-silicate/aluminate accelerators it’s replacing on Indian sites.
How is it applied?
Pumped continuously into the concrete stream at the nozzle through a calibrated dosing pump (never a piston pump) at roughly 40-70 ml per kg cement, with the working dosage fixed by an on-site trial panel.
About MC-Bauchemie MC-Montan Shotcrete HA 02
MC-Montan Shotcrete HA 02 sits inside MC-Bauchemie’s Montan range for tunnelling and mining — built for underground and rock-support work, not surface repair. Being alkali-free, it hardens sprayed concrete fast without the caustic sodium silicate/aluminate chemistry older “alkaline” accelerators used, which matters on a live tunnel face: gentler on the nozzleman, no free alkalis left in the matrix, and typically more ultimate strength retained. MC-Bauchemie’s datasheet lists it as EN 934-5 Type T2, third-party tested through KIT-MPA Karlsruhe, produced under ISO 9001/EN 934-2/6 factory control — the paper trail tunnelling consultants and metro/hydro contractors ask for before approving an accelerator on a QA-heavy programme.
On site it behaves like a precision input, not a bulk additive — dosed continuously at the nozzle rather than batched into the mixer, so the crew’s pump and calibration discipline matter as much as the chemistry. In India that plays out on metro tunnel drives, Himalayan hydropower headrace tunnels, hill-road slope stabilisation after blasting, and underground mine support, where a 15-20 cm shotcrete layer has to grip within minutes. Space Arc Engineering stocks and supplies HA 02 pan-India as an authorised MC-Bauchemie distributor and applicator, and supports the mock-up panel every such specification calls for.
The technical insight
Classic accelerators forced instant set by dumping free alkalis (Na2O/K2O, usually sodium silicate or aluminate) into the mix — effective, but those alkalis stay in the matrix, can feed alkali-silica reaction, and eat into long-term strength. Alkali-free accelerators like HA 02 instead use aluminium-sulfate-based dispersions that speed up ettringite formation in the cement paste, giving comparable early “stick” without the extra alkali load — why the datasheet can credibly claim high early strength with only a small drop in final strength.
Where it is used
- Tunnel primary lining under NATM/sequential excavation method
- Mine drift, gallery and drivage stabilisation
- Temporary rock-face securing after excavation or blasting
- Hillside and slope stabilisation shotcrete on cut faces
- Wet-mix and dry-mix shotcrete for metro and hydropower tunnels
- Underground cavern and powerhouse chamber support
- Rapid-set linings needing thick single-pass layers (15-20 cm)
- Emergency rock support in mining and civil excavation
Key advantages
- Alkali-free — no caustic burns risk for the nozzleman, no free-alkali left in hardened concrete
- High early strength with only a small penalty to final compressive strength
- Enables thicker single-pass layers (15-20 cm) — fewer passes, faster tunnel advance
- Lower rebound and dust at the nozzle — less waste, better crew visibility
- Works across both wet-mix and dry-mix shotcrete processes
- EN 934-5 Type T2 certified, third-party tested (KIT-MPA Karlsruhe, Notified Body 0754)
- ISO 9001/EN 934-2/6 factory production control for batch consistency
- Nozzle-side dosing keeps the accelerator out of pumped concrete until spraying
Limitations & considerations
- Imported chemistry — landed cost and lead time need planning despite local Space Arc stock
- Must never be stored in mild-steel drums or tanks — one more site-storage rule to enforce
- Needs a calibrated dosing pump at the nozzle; piston pumps are explicitly unsuitable
- Performance shifts with cement freshness, w/c ratio and site temperature — every project needs its own trial
- Higher dosage buys faster set at some cost to ultimate strength — must be engineered, not maximised
- Shelf life is time- and temperature-bound (6-12 months) — stock has to be rotated, not stockpiled
Selection & best practice
Treat HA 02 as an engineered input, not a generic add-and-spray additive. Trial it with the actual site cement, aggregate and mix design before production spraying, and lock the dosage — within 40-70 ml/kg, capped at 70 ml/kg per DIN 18551 — off that trial, not a datasheet default. Keep the dosing line calibrated and closed between shifts, use only the pump types MC-Bauchemie specifies, store off mild steel within the stated temperature band, and re-trial if cement source, season or mix design changes mid-project.
Specifications
| Chemistry / Type | Alkali-free liquid shotcrete accelerator, EN 934-5 Type T2 |
| Density (Specific Gravity) | 1.37 kg/dm³ ± 0.03 (SG ≈ 1.37) |
| Recommended Dosage | 40-70 ml per kg of cement |
| Max. Permissible Dosage | 70 ml per kg cement (per DIN 18551) |
| Colour / Form | Yellowish liquid |
| Standards Compliance | EN 934-5 (Type T2); factory production control to DIN EN ISO 9001 / EN 934-2/6; certified via KIT-MPA Karlsruhe (Notified Body 0754) |
| Storage Life | 6 months at 5-30°C in dry conditions (unopened); up to 12 months if stored cool and dry |
| Packaging | 230 kg drums; 1,000 kg IBC/containers |
| Application Method | Dosed at the spray nozzle via calibrated pump; suitable for both wet-mix and dry-mix shotcrete |
Industry use cases
Metro & Urban Tunnelling
NATM/SEM primary lining shotcrete for underground metro running tunnels and station caverns.
Hydropower & Hill Infrastructure
Headrace tunnel and underground powerhouse cavern support on Himalayan hydro projects.
Highway Slope Stabilisation
Rock-face shotcrete after hill-road cutting and blasting on Himalayan and North-East highway works.
Underground Mining
Drift, gallery and drivage support shotcrete in coal and metal mines.
Deep Basement & Retaining Works
Temporary shotcrete shoring on congested urban basement excavations.
Frequently asked questions
Is MC-Montan Shotcrete HA 02 chloride-free?
How does HA 02 compare with MC-Montan Shotcrete HA 01?
What dosage should we use?
Can we dose it with a standard piston pump?
How should it be stored on site?
Does it work for both dry-mix and wet-mix shotcrete?
How we position MC-Bauchemie MC-Montan Shotcrete HA 02
Within MC-Bauchemie’s range, HA 02 sits alongside MC-Montan Shotcrete HA 01 and the wider Montan tunnelling and mining systems line; Space Arc can help pick the right combination for a given tunnel or mine profile rather than specifying HA 02 alone. In India, specifiers most often shortlist it against Sika’s Sigunit range and BASF Master Builders Solutions’ MEYCO accelerators — both alkali-free liquid systems in the same NATM/mining/slope-stabilisation segment. Fosroc’s mainstream catalogue doesn’t carry a directly comparable alkali-free shotcrete accelerator, so it isn’t a genuine alternative here; where a project’s vendor list already runs on Fosroc for repair and waterproofing, that typically sits alongside — not in place of — a dedicated tunnelling brand for the accelerator itself.
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