Recent development in the field of cementing materials has brought forward many non-traditional binder systems. Engineers involved in the fields of emergency repairs and rapid ground support have been on the lookout for materials that allow rapid production, placement and, most of all, very rapid strength development kinetics. One binder system that fits the description is composed of ordinary Portland cement (OPC), calcium aluminate cement (CAC) and calcium sulfate (C$). However, this type of

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... inder also sometimes exhibits difficult workability that severely limits its use in regular cast in-place concrete. This limitation is overcome when using dry-mix shotcrete as a placement method, since the contact between water and cement occurs in the nozzle immediately before placement, workability problem are avoided. As a part of a graduate project at Laval University, 49 different mixes, including simple, binary and (mainly) ternary blends, were tested. Two majors parameters were studied, the development of compressive strength and the volumetric stability. The numerous binder compositions tested allowed the selection of a stable optimised formulation in regard of early compressive strength and volumetric stability. Finally, the selected formulation was successfully tested with industrial dry-mix shotcrete equipment to verify the large scale placement feasibility of such a product. Shotcrete (also known as sprayed concrete in many parts of the world) is a placement method for concrete. Shotcrete is defined as a mortar or concrete pneumatically projected at high velocity onto a surface (ACI 2005). The high velocity is essential to the process as it ensures an adequate compaction or consolidation and allows the material to stick to the sprayed surface. Without the proper compaction, quality shotcrete cannot be produce (ACI 2009). As any placement methods, different advantages of shotcrete make it more appropriate in certain situations. With its capacity to stick to vertical and overhead surfaces, shotcrete need only minimum, if any, formworks. To take full advantage of this specificity, shotcrete is best used in ground supports (tunnel, mine, slope stabilisation, etc.), overhead civil work reparation (bridge deck and parking lower surface, etc.) and where complex formworks make cast-in place concrete very expensive (ark type bridge, circular column repairs, etc.).