Shotcrete is a form of low-slump concrete that is applied pneumatically by propelling it onto a surface using compressed air. It features a modest water/cement ratio, elevated cement content, and usually incorporates small aggregates, typically no larger than pea gravel. Achieving compressive strengths surpassing 5,000 psi is commonplace. The adhesive properties of shotcrete enable its application on vertical and overhead surfaces without the necessity of formwork. Through meticulous quality control, it is possible to construct a wall surface with a thickness of 8 inches or more in a single application.
Schnabel, a seasoned shotcrete contractor, employs shotcrete primarily in the construction of both temporary and permanent facings for soil nail retention walls. Moreover, shotcrete can serve as a facing for various types of earth-retaining walls. In the case of soil nail walls, an initial 4 to 6-inch temporary shotcrete layer 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 surface of the permanent facing can exhibit diverse finishes, ranging from sculpted and stained to gun finished or finish-troweled, resembling a formed concrete wall.