On the use of blast-furnace slag in sprayed concrete applications

Abstract Cement replacement by additions is crucial to produce sprayed concrete with proper mechanical properties and durability. The use of blast-furnace slag to produce sprayed concrete for tunnel linings may be restricted due to its low reactivity. In this context, the objective of this study is to evaluate the chemical and mechanical properties of sprayed concrete produced with cement and blast-furnace slag as a partial cement replacement. Hydration kinetics were characterized by isothermal calorimetry, X-ray diffraction and evolution of temperature, while mechanical properties were evaluated by needle penetration resistance and compressive strength of extracted cores. Results showed that slag was activated by the accelerators employed and the minimum strength specified for a J 2 class from 10 to 60 min and at 24 h was achieved. Therefore, blast-furnace slag may be used in sprayed concrete applications when the average strength evolution class is specified.