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Sprayed concrete supports tunnel faces, galleries and cut slopes and lines channels and pools. The system is a pumpable base mix with a superplasticiser, an accelerator dosed at the nozzle, and often fibres.
General guidance based on the manufacturer data sheets. Site conditions differ: confirm the system with MCT before you start. Where we do not name a product, ask us and we will confirm the right one.
Pre-seal severe water infiltration with Sika-4a before spraying (Sika Sigunit Powder BA p.2). Sika-4a is mixed with ordinary Portland cement and sets rapidly to seal water entry through concrete, rock or masonry (p.1); use it at +5 °C to +35 °C (p.2).
Sika®-4a is used as preliminary waterproofing work on wet surfaces or where there is general infiltration of water, prior to the application of subsequent cementitious render or gunite. (TDS p.1)
Typical guidance: maximum aggregate 8 mm, water–cement ratio about 0.48, a superplasticiser is essential and fresh concrete above 15 °C (Sika Sigunit-15 AF 11 L PK p.2). Sikament NN PK is listed for sprayed concrete (p.1) at 0.5–2.5 % of cement (p.2).
Slabs and foundations Walls, columns and piers Slender components with densely packed reinforcements Sprayed concrete Textured surface finishes Pre-cast and pre-stressed concrete elements Bridges and cantilever structures (TDS p.1)
SikaTard-930 stabilises shotcrete mixes, for example about 8 hours at 0.4 % and about 20 hours at 1.0 % of cement; confirm by trials with the local cement (p.2). It must be added at the batching plant (p.2).
Mainly wet and dry spray shotcrete mixes where cement hydration is prevented until required i.e. (TDS p.1)
Sika Sigunit-15 AF 11 L PK is an alkali-free liquid accelerator for wet and dry spraying (p.1): 3–10 % of binder for layers up to 15 cm per pass, dosed by peristaltic pump (p.2). For dry gunite, add Sika Sigunit Powder BA or Sigunit Powder AF PK to the dry mix at 2–10 % of cement (Sika Sigunit Powder BA p.1, p.2).
Sika® Sigunit®-15 AF 11 L PK is suitable for use as an accelerator in both the dry and wet spray processes. The main uses of Sika® Sigunit®-15 AF 11 L PK are as follows: Shotcrete with high initial strength, Support at the face, In tunneling, In mining, In gallery construction, In shaft construct… (TDS p.1)
Sika® Sigunit® Powder BA is suitable for dry spray gunite mortar as well as concrete mixes. Sika® Sigunit® Powder BA is normally used for: Tunnels and galleries, Securing rock faces, Embankment and excavation stabilisation, Thin section concrete shells, Swimming-pools, Concrete repair work. (TDS p.1)
Sika® Sigunit® Powder AF PK is suitable for dry spray gunite mortar as well as concrete mixes. Sika® Sigunit® Powder AF PK is normally used for: Tunnels and galleries, Securing rock faces, Embankment and excavation stabilisation, Thin section concrete shells, Swimming-pools, Concrete repair work. (TDS p.1,2)
SikaFiber Force-60 is for sprayed concrete in tunnelling and ground stabilisation (p.1) at 3–10 kg/m³; extend mixing above 6 kg/m³ (p.2). Replacing steel mesh needs an engineer's design (p.2).
For most types of in-situ cast structural concrete and sprayed concrete to distribute stresses, increase structural properties or increase abrasion resistance. Sprayed concrete: Excavation stabilisation in tunnelling and mining, Rock and ground stabilisation, Temporary stabilisation, Replacement … (TDS p.1)
Sikacrete Gunit-103 is a dry-spray repair mortar for tunnel linings and large-volume repairs, up to 150 mm overhead in one application (p.1). Minimum 10 mm per coat and not below +5 °C (p.2).
Sikacrete® Gunit-103 is an ideal product for use in all general applications where large volume repair work is to be carried out using the mechanically applied dry spray system. Typical uses for Sikacrete® Gunit-103 are: Large volume repairs to reinforced concrete structures, Concrete repairs req… (TDS p.1)
Cure properly, especially at high temperatures, to prevent plastic and drying shrinkage (Sika Sigunit Powder BA p.2). Do not reuse rebound material (Sikacrete Gunit-103 p.2).
A starting point for a site proposal. Quantities, prices and the final specification follow a site visit or photos.
| Step | Product | Pack | Source |
|---|---|---|---|
| 1. Stop running water first | Sika-4a | — | TDS p.1 · May 2021, Version 01.01 |
| 2. Design the wet-mix base | Sikament NN PK | 05 ltr jerry can | TDS p.1 · June 2025, Version 03.01 |
| 3. Hold the mix until spraying | SikaTard-930 | — | TDS p.1 · May 2021, Version 02.01 |
| 4. Accelerate at the nozzle | Sika Sigunit-15 AF 11 L PK | 05 ltr jerry can | TDS p.1 · November 2025, Version 01.04 |
| 4. Accelerate at the nozzle | Sika Sigunit Powder BA | 15 kg Bag | TDS p.1 · October 2023, Version 01.02 |
| 4. Accelerate at the nozzle | Sika Sigunit Powder AF PK | — | TDS p.1,2 · November 2025, Version 01.01 |
| 5. Add fibres where designed | SikaFiber Force-60 | — | TDS p.1 · May 2021, Version 02.01 |
| 6. Repairs and thick linings by dry spray | Sikacrete Gunit-103 | 25 kg bag - minimum order 1 tonne. | TDS p.1 · May 2021, Version 02.01 |
Sigunit-15 AF 11 L PK is an alkali-free liquid for wet and dry spraying, with lower rebound and no extra groundwater pollution from leached alkalis (p.1). Sigunit Powder BA is added to dry gunite mixes (p.1).
The Sigunit-15 AF 11 L PK dosage guide covers layers up to 15 cm per pass (p.2). Sikacrete Gunit-103 allows up to 150 mm overhead in one application (p.1).
Pre-seal severe infiltration with Sika-4a (Sika Sigunit Powder BA p.2). Powder accelerators also give better adhesion on areas of slight seepage (Sika Sigunit Powder BA p.1).
Only when designed by a qualified engineer (SikaFiber Force-60 p.2).
Steps and product facts are taken from the manufacturer data sheets (page cited). Products are named only where the data sheet confirms the use; quantities follow a site visit or photos. General guidance: check the data sheet or ask us before you start.