Shotcrete (formerly known as Gunite) can be best described as pneumatically applied or sprayed concrete. Shotcrete mix designs are a combination of Portland cement, aggregates, water and admixtures. The admixtures can range from silica-fume and accelerators to steel or synthetic fibers.

These components are either mixed and then pumped to the nozzle (wet process) or pneumatically conveyed by compressed air through special hoses to the nozzle (dry process), where the material is “shot” or sprayed in place. Finish of the product can range from float or trowel finish to carved, colored textures.

Shotcrete, being sprayed concrete, results in a very durable product with structural properties. Mix designs are available to address needs such as high compressive strengths, long-term durability and early-age strength development.

Shotcrete is typically used to repair concrete on parking structures, bridges, dams, sewers, tunnels and marine structures. It is also commonly used in building swimming pools, tanks, sewer/tunnel linings, zoo enclosures, artificial rock walls and slope/surface protection.

Shotcrete can be applied in either the dry-mix process or the wet-mix process. Job site logistics, material mix design, production rates and position of area to be constructed are a few factors that should be considered when choosing which process should be used. Both processes have advantages and disadvantages that may make one or the other more desirable to meet the specific job requirements.