StructuralQ We are applying shotcrete in a slope (8 in. [200 m]) to make it stable. The shotcrete wall has a length of 330 ft (100 m). Do we need to specify construction and an isolation joint? In case it is required as well as an isolation joint, does the separation between joints need to be 30 ft (9 m)? Where can I find information about joints for shotcrete?
Shotcrete is a placement method for concrete. Thus, you should place movement joints (contraction, expansion, isolation) as would be required by your local design codes for concrete. Joint spacing will depend on the amount of reinforcement used in the section to resist temperature and shrinkage volume changes. Construction joint spacing can be determined by the contractor depending on their production rates. Properly prepared construction joints will act as monolithic concrete as long as the joints are properly prepared and proper concrete materials, equipment, and placement techniques are used by the shotcrete contractor. Construction joints should be roughened, cleaned, and then dampened to saturated surface-dry conditions before subsequent shotcrete placement.
The U.S. Bureau of Reclamation has a nice summary document that you may find helpful in your design.
