ABSTRACT
Reinforcement is used but assembly and fixing are rather different to normal reinforced concrete. The outer of the two reinforcement layers should not be fixed directly above the inner layer, but to one side, so that it does not shade the inner layer. Similarly, bars are not laid or lapped beside one another. Laps are formed with an open staggered pattern, no two adjacent bars being closer than 65 mm. Mesh is often used and is lapped 1½ squares in both directions to give an open overlap. Because of the blast of concrete from the nozzle all reinforcement and mesh must be securely fixed to the backing. Staples are used with a wood backing, such as formwork, and shot-fired pins with bendable clips are frequently used elsewhere. Reinforcement must be supported clear of the backing, the distance depending on the largest aggregate size and the tension function of the reinforcement.
