Frequently asked questions

Yes — this is one of shotcrete’s principal advantages. Because no formwork is required, it can be applied to steep, irregular, and elevated faces that would be impractical to cast conventionally. Access is achieved by scaffold, elevated work platforms, or rope-access teams. Our IRATA-qualified rope-access crews allow shotcrete, mesh, and anchor installation on high or difficult faces with minimal temporary works.

Shotcrete should not be applied to frozen substrates, during heavy rain that washes out fresh material, or in extreme heat and wind without protective measures. In hot, dry, or windy South African conditions, curing is essential — typically by water curing or membrane-forming curing compounds — to prevent plastic shrinkage cracking and ensure strength development.

Quality control covers the materials, the mix, and the applied product. Typical measures include:

• Pre-construction trials and test panels sprayed by each nozzleman to verify mix design and workmanship
• Cores drilled from test panels or the works for compressive strength testing
• Beam or panel tests for fibre-reinforced shotcrete to verify residual flexural strength or energy absorption
• Thickness verification by depth pins or coring
• Bond (pull-off) testing where bond to the substrate is specified

In South African roadworks, shotcrete for geotechnical applications is specified in terms of COTO Chapter 12 (Clause 12.5), read together with the relevant structural concrete specifications and SANS standards.

Shotcrete can be reinforced in several ways:

• Welded mesh or rebar fixed to the face before spraying — common in lateral support and slope facing work
• Steel fibres dosed into the mix, providing distributed ductility and post-crack load capacity, specified by residual flexural strength classes in terms of EN 14889-1
• Macro-synthetic fibres, used where corrosion resistance or specific energy-absorption requirements apply

Fibre-reinforced shotcrete eliminates much of the time and safety risk associated with fixing mesh on steep or unstable faces and is widely used in mining and tunnelling ground support.

With accelerated mixes used in underground support, shotcrete can achieve early strengths sufficient for re-entry within hours. Conventional mixes follow normal concrete strength development, reaching their specified characteristic strength at 28 days. Early-age strength requirements, where specified, are verified by penetration needle or pull-out testing.

Yes. Properly designed and applied shotcrete achieves compressive strengths equal to or exceeding conventional cast concrete — typically 25 MPa to 50 MPa or more at 28 days, depending on the mix design. Because the material is compacted by the velocity of placement, in-situ density and bond to the substrate are often superior. Quality, however, is highly dependent on the skill of the nozzleman and the application process, which is why specialist contractors and qualified operators are essential.

Properly specified and applied shotcrete is highly durable, with service lives comparable to conventional structural concrete. Durability depends on mix design (water/cement ratio, cement type, admixtures), adequate cover to reinforcement, compaction, and curing. For aggressive environments — marine exposure, acidic mine water, or sulphate-bearing ground — the mix is designed accordingly.

Costs depend on volumes, access, mix specification, reinforcement, and site logistics, so meaningful pricing requires project-specific information. As a general principle, shotcrete becomes highly cost-effective where formwork would be difficult or impossible, where ground must be supported quickly, or where irregular surfaces must be covered. We provide detailed, transparent rates at tender stage, including realistic allowances for rebound, access, and testing.

“ZOLULA”, the Xhosa word for “stretch” and Zulu word for “easy”. The word embodies a mindset shift of stepping outside of a comfort zone into a growth zone.

We believe that only when you stretch ourselves in terms of your comfort zone can we truly realise our full potential and deliver a meaningful impact in society.

On a personal note, some letters form an acronym for family names and serves as a reminder to keep family at the centre point of our endeavours’. In essence, focus on maintaining the “easy” part of life.

We solve South Africa’s toughest geotechnical challenges

Rebound is the portion of sprayed material that ricochets off the receiving surface and falls away. It is influenced by the process (dry-mix rebounds more than wet-mix), mix design, nozzle technique, and the orientation of the surface — overhead work rebounds most. Rebound material must never be worked back into the fresh shotcrete, as it consists largely of aggregate with little cement paste. Good practice keeps wet-mix rebound below roughly 5–10% on vertical faces; we account for realistic rebound allowances in our pricing and planning.

Shotcrete, also known as sprayed concrete, is concrete or mortar that is pneumatically projected at high velocity onto a surface through a hose and nozzle. The force of placement compacts the material against the substrate, producing a dense, well-bonded layer without the need for conventional formwork. The terms “shotcrete” and “sprayed concrete” are used interchangeably — “sprayed concrete” is the term generally used in European standards (EN 14487), while “shotcrete” is common in South African and American practice.

In the wet-mix process, all ingredients — including water — are batched and mixed before being pumped to the nozzle, where compressed air projects the material onto the surface. Wet-mix offers higher production rates, lower rebound, better dust control, and more consistent quality, making it the preferred method for larger volumes and structural applications.

In the dry-mix process (also called gunite), the dry cement and aggregate are conveyed through the hose by compressed air, with water added at the nozzle by the nozzleman. Dry-mix suits smaller volumes, intermittent work, long conveying distances, and confined or remote locations where wet-mix logistics are impractical.

The right process depends on the application, access, volumes, and programme — we advise on this during tender or design stage.

Sound surface preparation is critical to bond. Loose rock, soil, debris, and standing water must be removed, and the substrate is typically cleaned with air or air-water jetting before spraying. On repair work, deteriorated concrete is removed back to sound material and the surface roughened. Drainage provisions — such as weep holes or geocomposite drains — are installed before spraying where groundwater is present.

Typical layer thicknesses range from 50 mm to 150 mm, applied in one or more passes. Structural applications may require total thicknesses of 200 mm or more, built up in successive layers. The specified thickness is verified during application using depth pins, probes, or drilled cores.

Typical applications include:

• Slope stabilisation and lateral support — facing for soil-nailed and anchored excavations, cut slopes, and road or rail embankments
• Rockfall and landslide protection — surface support on weathered or fractured rock faces, often combined with mesh, anchors, and drainage
• Tunnelling and underground mining — primary and secondary ground support in shafts, declines, and tunnels
• Structural repair and rehabilitation — reinstatement of deteriorated concrete on bridges, culverts, dams, and marine structures
• Channel and canal linings, swimming pools, and architectural free-form structures

We are based in Technopark, Stellenbosch.

The nozzleman directly controls compaction, layer build-up, encapsulation of reinforcement, and rebound. A skilled operator maintains the correct nozzle distance and angle, works systematically from the bottom up, and properly encases mesh and fixings without creating shadows or voids. For this reason, specifications commonly require nozzlemen to demonstrate competence on test panels before working on the permanent works — a requirement we build into our quality plans as standard.

Shotcrete is an operator-dependent process where design intent is only realised through correct application. A specialist contractor brings qualified nozzlemen, purpose-suited pumping and spraying plant, proven mix designs, established quality systems, and the ability to integrate shotcrete with related geotechnical works — soil nails, ground anchors, drainage, and mesh systems — under a single point of responsibility.