Shotcrete: New developments and applications

This paper presents the most recent developments in shotcrete technology ob tained in the last 5 years through the "Industrial Chair on Shotcrete and C oncrete Repair" hosted at Laval University. The main goal of this paper is to inform those involved in the construction and repair of civil engineerin g concrete structures of the various possibilities of "shotcrete." The two first sections present the basic principles in pneumatic application of con crete along with the two processes in shotcrete technology, the dry-mix and wet-mix. The advantages of both processes as well as the general rules to follow in a shotcrete application are also presented and explained. The thi rd and last section, the most important, highlights the latest developments in shotcrete technology. These developments concern the use of set acceler ating admixtures in dry process shotcrete and their effects on the durabili ty of materials, the use of liquid and powdered air-entraining admixtures i n dry-mix shotcrete as well as the concept of "high initial air content" in wet mix shotcrete.