Wet-mix shotcrete that closes the surface and transfers load to the anchors. Decisions on mix, fibre and thickness follow the weathering rate of the surface and the need for drainage; thickness and strength are measured at handover.
The problem
Shotcrete is not a magic shell that strengthens a slope; it is a thin load-bearing layer that closes the surface, locks the blocks together and transfers load to the anchors. Where it is used correctly is clear: rocks that weather quickly in contact with air and water (claystone, marl, schist, weathered tuff), sections where the blocks interlock but the surface ravels, first support on tunnel and excavation faces, surface protection in channels and stream beds. Where it is used wrongly is just as clear: a slope face with no drainage. Such a lining traps water, pore water pressure builds up behind the shell and one day the layer breaks off.
The signs of a shell that was not applied properly are read on site: shrinkage cracks spreading like a net, a hollow sound showing that the layer has separated from the rock, water seeping from cracks and leaving lime traces, radial cracks around anchor plates, broken pieces collecting at the toe and blocked weep holes. These signs are not solved without renewing the lining; spraying a new layer on top hides the problem.
How we decide
The data we measure and set: rock type and degree of weathering, rate of deterioration in contact with air, discontinuity spacing and block size, water coming from the surface and its seasonal change, surface regularity, whether anchoring is feasible, application temperature and frost risk, whether the concrete is expected to carry load.
| Observation | Criterion | Decision |
|---|---|---|
| Surface weathers in air, blocks interlocked | No structural load expected | Thin lining, mesh or fibre, drainage with weep holes |
| Water coming from the surface | Pressure builds up behind the lining | Drainage first: weep holes, drainage line, horizontal drains |
| Blocks separating at the surface, load present | The shell will carry load | Rock bolts, steel mesh, thick layer |
| Very irregular surface with deep recesses | Thickness control difficult, high consumption | Surface regularization first, then lining |
| Weathering superficial, mass sound | No lining needed | Drapery with mesh, or scaling only |
| Natural surface appearance required | Concrete appearance not accepted | Mesh and bolt solution, or a textured lining |
In the choice of method, wet mix usually comes first: dust and rebound are lower, mix proportions are constant and can be recorded. Dry mix keeps its place in work with interruptions and long hose distances.
System family
| System | When suitable | Source |
|---|---|---|
| Wet-mix shotcrete | Continuous work, low dust, recorded mix | Artusa installation |
| Dry-mix shotcrete | Intermittent work, long lines, patching | Artusa installation |
| Steel or synthetic fibre mix | When post-crack strength and toughness are required | Artusa installation |
| Steel welded mesh and hexagonal double-twist mesh | Conventional reinforcement on regular surfaces | Artusa manufacturing and supply |
| With high-tensile anchored mesh | When the shell will transfer load to the anchors | Geobrugg |
| Rock bolt, anchor, drainage weep hole | Complementary in every thick lining | Artusa installation |
The rules of application are defined by EN 14487-1 (definitions and conformity) and EN 14487-2 (execution), and the tests by the EN 14488 series. In slope work the lining is not designed alone but together with rock bolts and drainage.
Installation
The sequence starts by making the surface acceptable. Loose pieces and vegetation are removed, the surface is cleaned with pressurized water or air and dampened, without leaving standing water. Anchors and bolts, if any, are installed before the lining. The reinforcement is placed, weep holes and the drainage line are fitted, and thickness gauge pins are driven in. Spraying goes from bottom to top with the nozzle held perpendicular to the surface at a constant distance; when the angle is wrong, rebound increases and the space behind the reinforcement is not filled. Thick sections are applied in layers, and curing starts as soon as application ends.
On steep faces access is set up by experienced specialists on rope access or with a basket platform; the hose route and pump position are part of the access plan. Checkpoints: consistency and temperature of fresh concrete, admixture and fibre dosage, layer thickness, reinforcement cover, rebound ratio, weep hole openings, curing time. There is no application while there is frost risk: working in winter conditions (Turkish).
Acceptance and maintenance
Measured at handover: thickness (by gauge pins and cores), compressive strength, post-crack toughness for fibre mixes, bond strength, reinforcement position and cover, number of weep holes and proof that they are open, mix and dosage records. The number and method of tests are written into the contract before work starts.
Monitored in maintenance: new cracks and their width, debonded zones giving a hollow sound, blocked weep holes, water and lime traces coming from cracks, peeling at the edge of the shell, damage around plates. If movement is expected, crack width is measured at marked points. Once the shell starts to break off, that zone must be rebuilt, not patched.
Frequently asked
- Is shotcrete applied on every slope? No; if water comes from the surface and drainage has not been solved, the lining makes the problem worse. The measurement list: what is measured on site (Turkish).
- Mesh or shotcrete? The two are not rivals: the mesh holds the movement, the lining protects the surface. Comparison: anchored mesh or drapery (Turkish).
- How is thickness proven? During application with gauge pins, at acceptance by core measurement. Measurement principles: how quantities are measured (Turkish).
Field record
2 projects in this family in our records, 2022–2025: Türkiye, Oman. Under confidentiality agreements, project and client names are not published.