Shotcrete stands out as a low-slump concrete applied pneumatically through compressed air onto the receiving surface. It features a low water/cement ratio, high cement content, and usually includes small aggregates not surpassing pea gravel size. Achieving compressive strengths exceeding 5,000 psi is common. The adhesive properties of shotcrete enable application on both vertical and overhead surfaces without requiring formwork. Rigorous quality control allows for constructing a wall surface with an 8-inch thickness or more in just one pass.
Schnabel, a seasoned shotcrete contractor, utilizes shotcrete primarily for constructing both temporary and permanent facings in the construction of soil nail retention walls. Its versatile application extends beyond soil nail walls, making it a suitable facing for various types of earth-retaining walls. In the case of soil nail walls, a preliminary shotcrete layer measuring 4 to 6 inches is directly applied to the excavated ground surface. For walls intended to be permanent, an additional 6 to 12 inches of reinforced shotcrete is applied subsequent to the installation of soil nails and the initial shotcrete layer. The final finish of the permanent facing can range from sculpted and stained to gun finished or finish-troweled, offering a diverse aesthetic akin to a formed concrete wall.