Shotcrete has been around for 100 years. While the early gunite, or dry-process shotcrete, grew in use and various applications around the world for shotcrete's first 50 years, it was in the second 50 years that great progress was made in three important areas.
First, the introduction of the rotary gun in 1957 allowed higher production rates and larger aggregate mixtures to be used in the dry-process, opening up new applications and increased flexibility in mixture proportioning. In the 1970s the development of practical concrete pumping equipment spurred the growth of the wet-process shotcrete application.
Second, the American Concrete Institute established Committee 506 on Shotcreting in 1942 for the purpose of producing shotcrete specifications and other documents on the practical use of the shotcrete method. In 1990, ASTM established Subcommittee C09.46 on Shotcrete to develop material specifications and test methods for shotcrete.
Finally, the development of a Nozzleman Certification program by ACI in 2001, with support from the American Shotcrete Association, allowed the industry to comply with existing specifications while increasing the technical knowledge and ability of nozzle operators throughout the world. By combining further advances in equipment, concrete technology, and operator proficiency, the shotcrete industry will continue to make significant advances in its second century.
—George D. Yoggy and Peter C. Tatnall
Read more highlights from 50 Years of Concrete Construction Progress.