ABSTRACT
This chapter provides a review of the different types of cements and supplementary cementing materials used in both dry-mix and wet-mix shotcretes. Particular emphasis is placed on supplementary cementing materials such as silica fume, which has remarkably beneficial attributes for shotcrete, enhancing adhesion and cohesion and the thickness of build-up achievable without sagging and sloughing, particularly in overhead shotcrete applications. The benefits of using high volumes of slag in mass shotcrete construction to reduce the heat of hydration and keep peak temperatures and differential thermal temperatures low are also discussed. Given that coarse and fine aggregates make up about 70% of the dry ingredients in shotcrete, there is a detailed review of the grading and durability requirements for aggregates used in shotcrete. Chemical admixtures play an important role in developing the required plastic and hardened properties in shotcrete and there is a comprehensive review of the influences of the various types of chemical admixtures on shotcrete behaviour, including air-entraining admixtures, water reducers, set-retarding and hydration-controlling admixtures and accelerators added in powder form in dry-mix shotcretes and in liquid form at the nozzle in wet-mix shotcrete. There is also information regarding the different types of fibres used in shotcrete.
