Repair, Safety, and Standards Compliance
Repair of shotcrete involves identifying defects-voids, delaminations, honeycomb, dry patches, overspray, and cracks-and removing unsound material to a sound substrate before patching. Repair procedures typically require chipping or saw-cutting to a defined edge, cleaning, pre-wetting, and reapplying shotcrete or a suitable repair mortar, often with bonding agent per specification. Candidates should understand that cosmetic patching over a void does not restore structural integrity; the defect must be removed and replaced. Cracks may be routed and sealed or injected depending on width and cause.
Safety is a major domain: shotcrete operations involve high-pressure lines, compressed air, dust (silica exposure), rebound, and overhead work. Key controls include proper PPE (respiratory protection, eye protection, hearing protection), wetting to control dust, securing hoses and fittings to prevent whipping, never standing in line with a pressurized hose, and safe access for overhead work. Nozzlemen and helpers need training and communication (hand signals or radios). Standards compliance means following the project specification and referenced standards for materials, testing, and safety-not substituting field judgment for specified requirements.
Rule of thumb: remove all unsound material to sound substrate before repair; and treat every pressurized line as dangerous-secure it, inspect fittings, and keep personnel out of the line of fire.