Author(s)

G. Bernardo, A. Guida, I. Mecca

Abstract

Shotcrete is a cement-based mixture pneumatically projected at high velocity onto a receiving surface. The material component of shotcrete is essentially concrete or sometimes mortar, but the process of shotcrete application is unique. This process allows a good compaction of concrete to be obtained without vibration. Compared to cast-in-place concrete, other important advantages of the shotcrete process are related to the reduction of the amount and time for formwork installation, removal, and associated labor costs, the very flexible logistics, very good working safety and good environmental conditions. Nowadays, because of the significant advances that occurred mainly in the last few decades, shotcrete can be considered a proper repair material particularly suitable in different situations such as where formwork is not practical or can be reduced or eliminated, where access to the work area is difficult, where thin layers and/or variable thickness is required and where normal casting techniques cannot be employed. This paper describes the two different application techniques of shotcrete, namely the dry-mix process and the wet-mix process, and discusses their respective advantages and disadvantages. The drawbacks of conventional shotcrete (only based on cement and aggregate mixtures) are reviewed and high performance shotcrete are presented. These novel shotcrete materials are produced through the addition of new generations of chemical admixtures, supplementary cementitious materials and reinforcement fibres. Cases histories of a successful use of the shotcrete process in the rehabilitations of architecturally important historic buildings are described.

Keywords

shotcrete, dry-mix process, wet-mix process, high performance shotcrete, rehabilitations, repairs, heritage building